BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
BMJ Open is committed to open peer review. As part of this commitment we make the peer review history of every article we publish publicly available.
When an article is published we post the peer reviewers’ comments and the authors’ responses online. We also post the versions of the paper that were used during peer review. These are the versions that the peer review comments apply to.
The versions of the paper that follow are the versions that were submitted during the peer review process. They are not the versions of record or the final published versions. They should not be cited or distributed as the published version of this manuscript.
BMJ Open is an open access journal and the full, final, typeset and author-corrected version of record of the manuscript is available on our site with no access controls, subscription charges or pay-per-view fees (http://bmjopen.bmj.com).
If you have any questions on BMJ Open’s open peer review process please email [email protected] http://bmjopen.bmj.com/ on September 30, 2021 by guest. Protected copyright. BMJ Open BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
Incidence of anorexia nervosa in young people in the United Kingdom and the Republic of Ireland: A national surveillance study ForJournal: peerBMJ Open review only Manuscript ID bmjopen-2018-027339
Article Type: Research
Date Submitted by the 17-Oct-2018 Author:
Complete List of Authors: Petkova, Hristina; King's College London, Health Service and Population Research Department Simic, Mima; South London and Maudsley NHS Foundation Trust Nicholls, Dasha; Imperial College London Ford, Tamsin; University of Exeter, Medical School Prina, A.Matthew; King's College London, Stuart, Ruth; King's College London, Health Service and Population Research Department Livingstone, Nuala; Queen's University Belfast Kelly, Grace; Queen's University Belfast Macdonald, Geraldine; University of Bristol Eisler, Ivan; South London and Maudsley NHS Foundation Trust
Gowers, Simon; University of Liverpool http://bmjopen.bmj.com/ Barrett, Barbara; King's College London Byford, Sarah; King's College London, Health Service and Population Research Department
Eating disorders < PSYCHIATRY, Child & adolescent psychiatry < Keywords: PSYCHIATRY, EPIDEMIOLOGY
on September 30, 2021 by guest. Protected copyright.
For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 1 of 27 BMJ Open BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
1 2 3 Incidence of anorexia nervosa in young people in the United Kingdom and the Republic of 4 5 Ireland: A national surveillance study 6 7 Hristina Petkova, Institute of Psychiatry, Psychology & Neuroscience at King’s College London 8 (Research Fellow). 9 10 Mima Simic, South London and Maudsley NHS Foundation Trust (Consultant Child and 11 12 Adolescent Psychiatrist). 13 14 Dasha Nicholls, Imperial College London (Reader in Child and Adolescent Psychiatry). 15 Tamsin Ford, University of Exeter Medical School (Professor of Child and Adolescent 16 For peer review only 17 Psychiatry). 18 19 A. Matthew Prina, Institute of Psychiatry, Psychology & Neuroscience at King’s College 20 21 London (Senior Lecturer in Epidemiology). 22 Ruth Stuart, Institute of Psychiatry, Psychology & Neuroscience at King’s College London 23 24 (Research Assistant). 25 26 Nuala Livingstone, Queen’s University Belfast (Research Fellow). 27 Grace Kelly, Queen’s University Belfast (Research Fellow). 28 29 Geraldine Macdonald, University of Bristol (Professor of Social Work). 30 31 Ivan Eisler, South London and Maudsley NHS Foundation Trust (Professor of Family 32 33 Psychology and Family Therapy). http://bmjopen.bmj.com/ 34 Simon Gowers, University of Liverpool (Professor of Adolescent Psychiatry). 35 36 Barbara Barrett, Institute of Psychiatry, Psychology & Neuroscience at King’s College London 37 38 (Senior Lecturer in Health Economics). 39 40 Sarah Byford, Institute of Psychiatry, Psychology & Neuroscience at King’s College London 41 (Professor of Health Economics). on September 30, 2021 by guest. Protected copyright. 42 43 44 45 Corresponding author: Sarah Byford, Institute of Psychiatry, Psychology & Neuroscience at 46 King’s College London, P024 David Goldberg Centre, De Crespigny Park, London SE5 8AF, 47 48 UK, [email protected], 02078480043 49 50 51 52 53 54 55 56 57 58 1 59 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 2 of 27 BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
1 2 3 Abstract 4 5 Objectives: This study aimed to estimate the incidence of DSM5 anorexia nervosa in young 6 7 people in contact with child and adolescent mental health services in the UK and Republic of 8 Ireland. 9 10 Design: Observational, surveillance study using the Child and Adolescent Psychiatry 11 12 Surveillance System, involving monthly reporting by child and adolescent psychiatrists between 13 st th 14 1 February 2015 and 30 September 2015. 15 Setting: UK and Republic of Ireland 16 For peer review only 17 Participants: Clinician-reported data on young people aged 8 to 17 in contact with child and 18 19 adolescent mental health services for a first episode of anorexia nervosa. 20 21 Main outcome measures: Annual incidence rates estimated as confirmed new cases per 100,000 22 population at risk. 23 24 Results: 305 incident cases of anorexia nervosa were reported over the 8-month surveillance 25 26 period and assessed as eligible for inclusion. The majority were young women (91%), from 27 England (70%), and of white ethnicity (92%). Mean age was 14.6 years (±1.66) and mean 28 29 percentage of median expected BMI for age and sex was 83.23% (±10.99%). The overall incidence 30 31 rate, adjusted for missing data, was estimated to be 13.68 per 100,000 population (95% CI 12.88 32 33 to 14.52), with rates of 25.66 for young women (95% CI 24.09 to 27.30) and 2.28 for young men http://bmjopen.bmj.com/ 34 (95% CI 1.84 to 2.79). Incidence increased steadily with age, peaking at 15 for young women 35 36 (57.77, 95% CI 50.41 to 65.90) and 16 for young men (5.14, 95% CI 3.20 to 7.83). Comparison 37 38 with earlier estimates suggests incidence rates for children aged 13 and under have increased over 39 40 the last ten years. 41 Conclusions: These results provide up-to-date estimates of the incidence of anorexia nervosa in on September 30, 2021 by guest. Protected copyright. 42 43 young people. Service providers and commissioners should consider evidence to suggest an 44 45 increase in incidence in younger children. 46 Study registration: International Standard Randomised Controlled Trial Number Register 47 48 [ISRCTN12676087]. 49 50 51 52 53 54 55 56 57 58 2 59 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 3 of 27 BMJ Open BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
1 2 3 Strengths and limitations of this study 4 5 Estimates of the incidence of anorexia nervosa in the UK and Republic of Ireland are 6 7 limited and at least ten years old. 8 9 This study provides up-to-date estimates of the incidence of DSM5 anorexia nervosa in 10 young people aged 8 to 17 years in contact with child and adolescent mental health 11 12 services across the UK and Republic of Ireland. 13 14 The surveillance design of this observational study ensured a large, nationally 15 16 representativeFor sample. peer review only 17 Missing data due to non-response was a limitation and required adjustments to observed 18 19 data to account for the impact of this missing data. 20 21 22 23 24 25 26 27 28 29 30 31 32 33 http://bmjopen.bmj.com/ 34 35 36 37 38 39 40 41 on September 30, 2021 by guest. Protected copyright. 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 3 59 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 4 of 27 BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
1 2 3 Introduction 4 5 Anorexia nervosa is a serious and enduring eating disorder with high morbidity and the highest 6 1 7 mortality among psychiatric disorders. Young women are particularly susceptible, with annual 8 UK estimates of 37 new diagnoses of anorexia nervosa per 100,000 for girls aged 10 to 19 years, 9 10 compared to 3 per 100,000 for boys of the same age.2 Prevalence estimates in young people 11 12 range from 0.3% to 0.6%.3–4 13 14 15 Accurate epidemiological estimates of the number of new anorexia nervosa cases per year and 16 For peer review only 17 their sex and age profile are needed for causal investigations and service planning.2 However, 18 2,5–7 19 available estimates in the UK are at least ten years old. In addition, most estimates are 20 2,5 21 derived from community-based primary care records, which fail to accurately record all new 22 cases.8,9 Undetected anorexia nervosa cases may present to accident and emergency and require 23 24 immediate paediatric or psychiatric input, including inpatient admission. Some young people 25 10 26 may therefore bypass primary care and, consistent with UK guidelines, are likely to be assessed 27 and diagnosed by a child and adolescent psychiatrist in a secondary care setting, making 28 29 secondary care records a more reliable source of data on anorexia nervosa incidence than 30 31 primary care registers. 32 33 http://bmjopen.bmj.com/ 34 Existing incidence data from secondary care settings in the UK are limited. One study, focusing 35 36 only on adolescents aged 13 to 18, was limited to Greater London and reported presentation rates 37 38 to child and adolescent mental health services (CAMHS), rather than incidence estimates.6 A 39 7 40 second study, which used a national surveillance design, focused only on children under 13. The 41 current study aimed to estimate the incidence of anorexia nervosa in secondary care services for on September 30, 2021 by guest. Protected copyright. 42 43 young people between the ages of 8 and 17 years in the UK and the Republic of Ireland. This 44 45 work formed part of a study exploring the cost-effectiveness of models of care for young people 46 with eating disorders (the CostED study).11 47 48 49 50 Methods 51 52 Design 53 An observational, surveillance study was undertaken using the Child and Adolescent Psychiatry 54 55 Surveillance System (CAPSS). CAPSS is a system designed to ascertain cases of rare childhood 56 57 58 4 59 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 5 of 27 BMJ Open BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
1 2 3 mental health conditions in the UK and Republic of Ireland through monthly reporting by 4 5 clinicians and relies on non-consent to maximise the accuracy of epidemiological estimates. The 6 12 7 CAPSS system has been operating since 2009 and is based on the well-established British 8 Paediatric Surveillance Unit (BPSU) system.13 9 10 11 12 Ethics approvals 13 14 The study was approved by the CAPSS Executive Committee, King’s College London Research 15 Ethics Committee [PNM/13/14-105], and the Health Research Authority Confidentiality 16 For peer review only 17 Advisory Group [CAG 4-03(PR1)/2014] under Section 251 of the NHS Act 2006, which enables 18 19 disclosure of confidential patient information for purposes where it is not possible to use 20 21 anonymised information and where seeking consent is not practical. 22 23 24 Patient and public involvement 25 26 The CostED study included a patient and a parent representative on the study steering committee 27 who contributed to the design, conduct and management of the study, including the incidence 28 29 component. A lay summary of the CostED study results will be produced, in collaboration with 30 31 Beat, the national eating disorder charity, for dissemination via the Beat website. 32 33 http://bmjopen.bmj.com/ 34 Inclusion and exclusion criteria 35 36 The study included young people between 8 and 17 years of age, in contact with CAMHS for a 37 38 first episode of anorexia nervosa according to DSM5 diagnostic criteria.14 New cases were 39 st th 40 notified for a period of eight months from 1 February to 30 September 2015. Cases whose 41 clinician-reported data were insufficient to assess eligibility were excluded, as were duplicate on September 30, 2021 by guest. Protected copyright. 42 43 cases notified more than once by the same or different clinicians. 44 45 46 Procedures 47 48 At the time of the study, CAPSS used a report card, known as the yellow card, containing a list 49 50 of conditions being surveyed. Yellow cards, along with reporting instructions and protocols for 51 52 new studies, are sent monthly from the CAPSS office to a mailing list of all hospital, university 53 and community child and adolescent consultant psychiatrists across the United Kingdom and the 54 55 Republic of Ireland. Reporting clinicians are asked to check boxes against any of the reportable 56 57 58 5 59 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 6 of 27 BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
1 2 3 conditions they have seen in the preceding month, or to check a "nil return" box and return the 4 5 card to CAPSS. A tear-off slip is provided for respondents to keep a record of the patients 6 7 reported. "Positive" returns are allocated a unique CAPSS ID number and notified to the 8 appropriate research investigator, who then contacts the reporting clinician directly to request 9 10 completion of a questionnaire using the CAPSS ID to enable the clinician to identify the relevant 11 12 patient. 13 14 15 For the CostED study, the yellow card contained a check box for anorexia nervosa and was sent 16 For peer review only 17 to clinicians along with a protocol card detailing the case notification definition for anorexia 18 19 nervosa. The case notification definition (see web extras) was based on DSM5 diagnostic criteria 20 21 for anorexia nervosa and was intended to aid clinicians in their decision to tick “yes” or “no” on 22 the yellow card. It was not intended to identify whether a case met study inclusion criteria, which 23 24 was determined by the research group after receipt of all necessary data. 25 26 27 Data 28 29 Questionnaires sent to clinicians reporting a positive case of anorexia nervosa, identified via the 30 31 unique CAPSS ID number, were completed from clinical records and clinicians requested to 32 33 provide data relating to the time the case was initially assessed and diagnosed. The questionnaire http://bmjopen.bmj.com/ 34 covered clinical features to enable assessment of case eligibility, referral pathway information to 35 36 ensure assessment and diagnosis had not happened prior to the study surveillance period, and a 37 38 limited set of standard patient identifiers in line with CAPSS procedures and ethics requirements, 39 40 which were used to describe the sample and to identify duplicate notifications. In addition, 41 clinicians were asked to confirm whether the case was a first episode of anorexia nervosa that on September 30, 2021 by guest. Protected copyright. 42 43 had come to the attention of services. 44 45 46 The patient identifiers included NHS or Community Health Index (CHI) number (unique patient 47 48 identifiers used in the regions of interest), hospital number, first half of postcode or town of 49 50 residence for the Republic of Ireland, sex, date of birth and ethnicity (White, Mixed, Asian, 51 52 Black, Chinese, Other or Unknown). In Northern Ireland, identifiers were limited to age in years 53 and months and hospital identifier rather than hospital number, to reduce the risk of patient 54 55 identification given the small geographic area. All patient identifiable data from Northern Ireland 56 57 58 6 59 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 7 of 27 BMJ Open BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
1 2 3 were retained by the local research team, de-duplicated, anonymised and subsequently sent to the 4 5 central research team in King’s College London for analysis as per requirements set out by the 6 7 Northern Ireland Privacy Advisory Committee. All data storage was compliant with the EU 8 General Data Protection Regulations. 9 10 11 12 Clinical features included: weight and height to calculate body mass index (BMI) and percentage 13 15 14 of median expected BMI for age and sex interpreted around the 85% threshold; The Health of 15 the Nation Outcome Scales for Children and Adolescents (HoNOSCA16), a routine outcome 16 For peer review only 17 measure rating 13 clinical features on a five-point severity scale including behaviours, 18 19 impairments, symptoms, and social functioning of children and adolescents with mental health 20 17 21 problems; the clinician completed Children's Global Assessment Scale (CGAS ) used to rate 22 emotional and behavioural functioning of young people; and a range of symptoms relating to the 23 24 diagnosis of anorexia nervosa. 25 26 27 Unreturned or incomplete questionnaires were chased via email and telephone. Cases where any 28 29 symptom required for case definition was absent despite chasing, were assessed for eligibility by 30 31 a consultant child and adolescent psychiatrist (MS). 32 33 http://bmjopen.bmj.com/ 34 Case eligibility 35 36 Cases were assessed as eligible for the study if: (a) they were between 8 and 17 years of age; (b) 37 38 they had no previous episode of anorexia nervosa that had come to the attention of services; (c) 39 40 they received a clinical assessment in the reporting service during the study surveillance period; 41 (d) they had not been referred from another secondary health service (to ensure assessment and on September 30, 2021 by guest. Protected copyright. 42 43 diagnosis had not happened prior to study surveillance period); and (e) the following clinical 44 45 symptoms were present: “Restriction of energy intake relative to requirements” and “Persistent 46 behaviour that interferes with weight gain, despite low weight”. This broad definition was 47 48 subsequently checked using a tighter DSM5 analytic definition including the following 49 50 symptoms: 51 52 1) “Restriction of energy intake relative to requirements” and 53 2) “Intense fear of gaining weight or of becoming fat” or “Persistent behaviour that 54 55 interferes with weight gain, despite low weight” and 56 57 58 7 59 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 8 of 27 BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
1 2 3 3) “Perception that body shape/size is larger than it is” or “Preoccupation with body weight 4 5 and shape” or “Lack of recognition of the seriousness of the current low body weight” 6 7 Only one case which met the broad criteria failed to meet the tighter criteria, thus confirming the 8 validity of the broad criteria. 9 10 11 12 Removal of duplicates 13 14 Duplicates were identified by comparing NHS/CHI numbers, hospital numbers/ hospital 15 identifiers and date of birth/age in years and months, as appropriate. The management of 16 For peer review only 17 duplicates depended upon the outcome for the original notification for which a duplicate was 18 19 identified. Four scenarios were considered: (1) duplicates where the original notification met 20 21 study inclusion criteria were excluded and the original retained; (2) duplicates where the original 22 notification had been excluded because the young person was under 8 years of age or did not 23 24 meet the clinical criteria were assessed as a new case to determine if the case now met eligibility 25 26 criteria; (3) duplicates where the original notification was excluded due to a previous episode of 27 anorexia nervosa, a diagnosis date prior to the study surveillance period or referral from another 28 29 secondary care service, were excluded; and (4) duplicates where the original notification 30 31 contained insufficient information to judge eligibility were checked to see if the duplicate 32 33 contained the missing information and, if available, the original notification was reassessed for http://bmjopen.bmj.com/ 34 eligibility and the duplicate managed as per the scenarios above. 35 36 37 38 Data analysis 39 40 Data analysis was performed using Stata IC v14.2 and Microsoft Excel 2010. Observed 41 incidence rates (denoted IR0), defined as the number of new cases during a specified period of on September 30, 2021 by guest. Protected copyright. 42 43 time in a population at risk for developing the disease, were calculated as follows: the number of 44 45 confirmed new cases of anorexia nervosa in the 8-month surveillance period converted to 12 46 months [(N cases over 8 months/8)*12], divided by the population at risk and multiplied by 47 48 100,000 to give the rate per 100,000 young people. 49 50 51 52 IR0 = (confirmed new cases converted to 12 months)/the population at risk *100,000 53 54 55 56 57 58 8 59 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 9 of 27 BMJ Open BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
1 2 3 The population at risk was calculated as the total number of children of each year of age and 4 5 each sex in the UK and Republic of Ireland minus the number of prevalent cases who, once 6 7 diagnosed, are no longer part of the “at risk” population. Population data for 2015 were obtained 8 from the Office for National Statistics for the UK18 and the Central Statistics Office for the 9 10 Republic of Ireland.19 To estimate the number of prevalent cases each year, incident cases in the 11 12 previous age band were used as a proxy. For example, incident cases aged eight were used as a 13 14 proxy for prevalent cases in the estimation of the ‘at risk’ population aged nine, and so on. 15 16 For peer review only 17 To consider incidence among unobserved missing cases, adjustments were needed for unreturned 18 19 CAPSS notification cards and questionnaires. For CAPSS notification cards, just over half of all 20 21 notification cards sent out were returned (50.16%). To account for incidence among the 49.84% 22 of unreturned cards, two assumptions were made, and an appropriate correction applied to IR0, 23 24 the observed incidence rate: 25 26 27 Assumption 1: To take into consideration the possibility that unreturned cards are more likely to 28 29 be ‘nil’ returns, it was assumed that half of unreturned cards (24.92%) were ‘negative’ and half 30 31 followed the same proportion of ‘negative’ and ‘positive’ as the returned cards. This assumption 32 33 translates into a correction coefficient of 1.50 derived from (24.92+50.16)/50.16. http://bmjopen.bmj.com/ 34 35 36 Assumption 2: Making no assumptions of bias in the likelihood of unreturned cards being either 37 38 positive or negative returns, it was assumed that all unreturned cards followed the same 39 40 proportion of ‘negative’ and ‘positive’ as returned cards. This assumption translates into a 41 correction coefficient of 1.99 derived from (49.84+50.16)/50.16. on September 30, 2021 by guest. Protected copyright. 42 43 44 45 These assumptions provide a range of incidence rates, from a minimum (observed incidence rate) 46 to a maximum (assumption 2), within which the actual rate is likely to fall. We hypothesised that 47 48 assumption 1 provides the most realistic estimate since it assumes a bias in the response rates 49 50 with greater likelihood that unreturned cards are negative (‘nil’ returns) but does not assume all 51 52 unreturned cards are ‘nil’ returns, which is the implicit assumption within IR0. 53 54 55 56 57 58 9 59 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 10 of 27 BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
1 2 3 For unreturned questionnaires, approximately two-thirds of the questionnaires that were sent to 4 5 clinicians reporting positive cases of anorexia nervosa were returned (63%), leaving one-third 6 7 (37%) unreturned. Since all these questionnaires relate to a ‘positive’ notification, we applied a 8 correction coefficient of 1.59 derived from (37+63)/63, which assumes that the incidence rate for 9 10 the unreturned questionnaires is the same as the incidence rate identified in the returned 11 12 questionnaires for each year of age. 13 14 15 We then combined the correction coefficients described above, to generate two adjusted 16 For peer review only 17 incidence rates: 18 19 20 21 Adjusted incidence rate 1 (IR1) = Confirmed new cases of anorexia nervosa converted to 12 22 months, multiplied by the correction for unreturned CAPSS notification cards under assumption 23 24 1, multiplied by the correction for unreturned questionnaires, then divided by the population at 25 26 risk and multiplied by 100,000. 27 28 29 IR1 = (confirmed new cases converted to 12 months * 1.50 * 1.59)/the population at risk 30 31 *100,000 32 33 http://bmjopen.bmj.com/ 34 Adjusted Incidence rate 2 (IR2) = Confirmed new cases of anorexia nervosa converted to 12- 35 36 months, multiplied by the correction for unreturned CAPSS notification cards under assumption 37 38 2, multiplied by the correction for unreturned questionnaires and then divided by the population 39 40 at risk and multiplied by 100,000. 41 on September 30, 2021 by guest. Protected copyright. 42 43 IR2 = (confirmed new cases converted to 12 months * 1.99 * 1.59)/the population at risk * 44 45 100,000 46 47 48 For each incidence rate, IR0, IR1 and IR2, total, age-specific and sex-specific annual incidence 49 50 rates for anorexia nervosa for the year 2015 and 95% confidence intervals were calculated based 51 20 52 on the Poisson distribution using the Stata command ci means [N new anorexia nervosa cases 53 12m], Poisson [exposure(total population)] for positive integers/whole incidence numbers (Stata 54 55 56 57 58 10 59 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 11 of 27 BMJ Open BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
1 2 3 interprets any non-integer decimal point number between 0 and 1 as the fraction of events and 4 5 converts it to an integer number). Annual incidence rates were stratified by discrete age and sex. 6 7 8 Results 9 10 Case ascertainment 11 12 Case ascertainment is outlined in Figure 1. Over the eight-month surveillance period, 6401 13 14 yellow cards were sent to reporting clinicians and 3211 were returned (50%). Of these, 997 15 positive cases of anorexia nervosa were reported and 2214 were nil returns. Of the positve cases, 16 For peer review only 17 48 (5%) were excluded due to clinicans stating that they did not wish to be included in the study 18 19 (due to retirement, shortage of reporting capacity etc.) or due to reporting errors. Questionnaires 20 21 were sent to the remaining 949, and a further 352 positive cases (37%) were excluded as they 22 failed to return the questionnaires, so no data were available to assess eligibility. Questionnaires 23 24 were completed and returned for 597 notified cases, of which 292 (49%) were ineligible for 25 26 reasons related to age, previous episode of anorexia nervosa, date of assessment outside the 27 study’s surveillance period, referral from another secondary care service, insufficient information 28 29 to assess diagnosis or duplicate notifications, leaving 305 incident cases of anorexia nervosa as 30 31 the sample for analysis. 32 33 http://bmjopen.bmj.com/ 34 Demographics and clinical features 35 36 Of the 305 young people identified as having DSM5 anorexia nervosa, the majority were girls 37 38 (91%), from England (70%) and of white ethnicity (92%) (see Table 1). The mean age was 14.6 39 40 years (±1.66). Clinical variables suggest these young people were significantly impaired. Mean 41 BMI was 16.50 kg/m2 (±2.25), where values of 16.00 to 16.99 suggesting moderate severity of on September 30, 2021 by guest. Protected copyright. 42 43 anorexia nervosa. Mean percentage of median expected BMI for age and sex (the deviation from 44 45 expected body weight) was 83.23% (±10.99%), falling within the range required for a diagnosis 46 of anorexia nervosa (<85%). Mean CGAS score was 44.61 (±14.08), which falls within the range 47 48 for ‘obvious problems’ (41–50) on a scale from 1 to 100 (1 being the worst and 100 the best 49 50 emotional and behavioural functioning). Mean total HoNOSCA score was 19.40 (±8.17) on a 51 21,22 52 scale from 0 to 52, indicative of a severity similar to that at inpatient admission. 53 54 55 56 57 58 11 59 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 12 of 27 BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
1 2 3 The proportion of the included sample notified from each region within the British Isles is 4 5 reported in Table 2, alongside the population of young people in each region by age. England has 6 7 the largest population (78%) and notified 70% of new cases. Scotland, containing only 7% of the 8 total population, notified 14% of the sample and Northern Ireland, containing only 3% of the 9 10 population, notified 13% of the sample. By contrast, the Republic of Ireland notified only 2% of 11 12 cases, despite containing 8% of the population, and Wales notified no eligible cases (some cases 13 14 were notified but did not meet inclusion criteria), despite containing 4% of the population. 15 16 For peer review only 17 Incidence rates 18 19 Table 3 details observed incidence rates (IR0) and adjusted incidence rates (IR1 and IR2) by age. 20 21 Incidence rates for the total sample ranged from a minimum of 5.75 per 100,000 young people 22 (95% CI 5.23 to 6.30; IR0) to a maximum of 18.22 per 100,000 young people (95% CI 17.29 to 23 24 19.18; IR2), with IR1, the rate hypothesised to be the most accurate, falling between these two 25 26 values at 13.68 per 100,000 population (95% CI 12.88 to 14.52). Focusing on IR1 rates, total 27 incidence increased steadily with age, peaking at 16 (30.37, 95% CI 26.70 to 34.41), with a 28 29 substantial drop at the age of 17 (14.35, 95% CI 11.88 to 17.19). 30 31 32 33 Table 4 reports incidence rates by age and sex. Incidence among young men followed a similar http://bmjopen.bmj.com/ 34 pattern to overall incidence rates reported in Table 3, being highest at the age of 16 (5.14) and 35 36 half that at age 17 (2.54). The highest incidence among young women was seen a year earlier 37 38 than for boys, at the age of 15 (57.77), with similar rates at age 16 (56.95), dropping by more 39 40 than half at age 17 (26.82). 41 on September 30, 2021 by guest. Protected copyright. 42 43 Discussion 44 45 Principal findings 46 This study provides up-to-date estimates of incident cases of anorexia nervosa in young people 47 48 aged 8 to 17 presenting to CAMHS services in the UK and Republic of Ireland. Our mid-range, 49 50 missing data-adjusted estimate (IR1) of the incidence of anorexia nervosa in the full sample of 51 52 young people aged 8 to 17 years was approximately 14 per 100,000. 53 54 55 56 57 58 12 59 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 13 of 27 BMJ Open BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
1 2 3 Comparison with other studies 4 5 This result is lower than previous primary care-based estimates of 18–20 per 100,000 focusing 6 2,5 7 on young people aged 10–19. This difference is due to the different age ranges in the studies; 8 the inclusion of children as young as 8 in the current study, who have relatively low incidence, 9 10 and exclusion of adolescents aged 18 to 19, whose incidence is relatively high, makes the results 11 12 difficult to compare. However, comparing rates for 10 to 14-year olds, available in both studies, 13 14 produces similar incidence rates, with rates of 12.6 per 100,000 in the current study, compared to 15 13.1 per 100,000 in 2009.2 For females, the rates are 23.3 per 100,000 in the current study 16 For peer review only 17 compared to 24.0 per 100,000 in 2009 and for males, 2.4 and 2.5 per 100,000, respectively. 18 19 However, this comparison should be treated with caution given the very different settings – 20 21 primary care versus secondary care. 22 23 24 Existing secondary care estimates of the incidence of anorexia nervosa in the UK are limited to 25 26 children under the age of 13, with an overall incidence of 1.09 per 100,000 reported for children 27 aged between 6 and 13 between 2005 and 2006.7 The methodology for this study was very similar 28 29 to the CostED methodology, using the CAPSS system but additionally the British Paediatric 30 31 Surveillance System. For comparison with the current study, the incidence rate for children 32 33 between 8 and 13 was approximately 1.5 per 100,000 for DSMIV anorexia nervosa or 1.8 per http://bmjopen.bmj.com/ 34 100,000 for DSMIV anorexia nervosa plus ‘other eating disorders’ likely to contain cases that 35 36 would now be classified as anorexia nervosa using DSM5. This compares to a rate of 5.83 per 37 38 100,000 in the current study for children of the same age. This estimate is substantially higher than 39 40 the 2006 estimates suggesting that incidence rates for younger children have increased over time. 41 on September 30, 2021 by guest. Protected copyright. 42 43 Strengths and weaknesses of the study 44 45 The large, nationally representative sample of this study is a strength. It included young people 46 with anorexia nervosa, diagnosed using DSM5 criteria, from across the UK and the Republic of 47 48 Ireland and thus avoided biases inherent in studying clinical samples via a small number of 49 50 centres in a limited number of geographical areas. 51 52 53 With only a 50% response rate from CAPSS clinicians and a third of questionnaires not returned, 54 55 missing data were a constraint. There are many reasons why clinicians may fail to return 56 57 58 13 59 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 14 of 27 BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
1 2 3 notification cards or questionnaires, including changes in place of employment, competing 4 5 priorities, or the belief that cases will be reported by a colleague.13 This problem was addressed 6 7 by adjusting the observed incidence rates using assumptions about incidence among both missing 8 case notifications and missing questionnaires. 9 10 11 12 The methodology is also limited to young people seen by child and adolescent psychiatrists. 13 14 Cases that would not be identified by this methodology include those who have not come to the 15 attention of services, those managed by general practitioners in primary care, and those in the 16 For peer review only 17 care of mental health services without psychiatric input, such as nurse-led facilities. This latter 18 19 concern was an issue in Northern Ireland where, due to initial low numbers of notifications, 20 21 investigation by the research team identified a number of nurse-led facilities which were invited 22 to contribute, and subsequently reported just over half of all cases in Northern Ireland. In terms 23 24 of missing primary care cases, given UK guidelines for assessment and diagnosis of anorexia 25 10 26 nervosa to be carried out by child and adolescent psychiatrists in secondary care settings, it is 27 reasonable to assume that many of those cases remaining in primary care would not meet criteria 28 29 for DSM5 anorexia nervosa. 30 31 32 33 Meaning of the study http://bmjopen.bmj.com/ 34 These results provide up-to-date estimates of the incidence of anorexia nervosa in young people. 35 36 Whilst firm conclusions relating to changes in incidence rates over time for the entire sample 37 38 cannot be drawn due to lack of existing secondary care evidence, service providers and 39 40 commissioners should consider evidence to suggest an increase in incidence in younger children. 41 on September 30, 2021 by guest. Protected copyright. 42 43 Unanswered questions and future research 44 45 Future research should explore the development of earlier interventions, given evidence of an 46 increase in incidence in young children suggesting that onset of anorexia nervosa may be starting 47 48 earlier for some young people than suggested by previous research. Research is also needed to 49 50 identify approaches to the assessment of incidence simultaneously in primary and secondary 51 52 care. 53 54 55 56 57 58 14 59 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 15 of 27 BMJ Open BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
1 2 3 Word count 4 5 3686 6 7 8 Acknowledgements 9 10 The authors would like to thank all the clinicians who were kind enough to give up their time to 11 12 provide the CostED study with CAPSS notifications and to complete questionnaires. We know 13 14 your time is precious and in short supply and we are truly grateful. We would also like to thank 15 the team at the Child and Adolescent Psychiatry Surveillance System, based at the Royal College 16 For peer review only 17 of Psychiatrist’s Centre for Care Quality and Improvement, for their support with the design and 18 19 running of the surveillance aspect of this study. Finally, we would like to thank the members of 20 21 the CostED study steering committee for their time and their support. 22 23 24 25 26 27 28 29 30 31 32 33 http://bmjopen.bmj.com/ 34 35 36 37 38 39 40 41 on September 30, 2021 by guest. Protected copyright. 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 15 59 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 16 of 27 BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
1 2 3 Contributors 4 5 SB was principal investigator, led the study and managed the King’s College London research 6 7 staff. GM managed the Northern Ireland research staff. SB and IE conceived the study. SB, IE, 8 GM, MS, DN, TF, SG and BB designed the study. MS, DS, TF, IE, SG provided clinical 9 10 expertise. DN and TF provided expertise on CAPSS methodology. HP, RS, NL and GK 11 12 contributed to data collection, data entry and data cleaning. SB, HP, MP and BB carried out the 13 14 data analysis. SB and HP drafted the manuscript. All authors have seen, commented on and 15 approved the final version of the manuscript. 16 For peer review only 17 18 19 Funding 20 21 The study was funded by the NIHR Health Service & Delivery Research programme 22 (11/1023/17). The study funders had no role in the study design, the collection, analysis or 23 24 interpretation of data, the writing of the report, or the decision to submit the article for 25 26 publication. The authors were independent from the funders and all authors had full access to all 27 of the data in the study and can take responsibility for the integrity of the data and the accuracy 28 29 of the data analysis. 30 31 32 33 Disclaimer http://bmjopen.bmj.com/ 34 The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or 35 36 the Department of Health and Social Care. 37 38 39 40 Competing interests 41 TF reports she is Chair of the Child and Adolescent Psychiatry Surveillance Service that was used to run on September 30, 2021 by guest. Protected copyright. 42 43 part of the study, which is an unpaid position (other than travel expenses). KJ reports that he was principal 44 investigator for the Aberdeen site for a Sunovion sponsored multisite trial on effectiveness of Lurasidone 45 46 in paediatric schizophrenia. No other authors report conflicts of interest. 47 48 49 Data sharing 50 51 No additional data available 52 53 54 55 56 57 58 16 59 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 17 of 27 BMJ Open BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
1 2 3 References 4 5 1 Arcelus J, Mitchell AJ, Wales J, Nielsen S. Mortality rates in patients with anorexia 6 7 nervosa and other eating disorders: A meta-analysis of 36 Studies. Arch Gen Psychiatry 8 2011;68:724–731. 9 10 2 Micali N, Hagberg KW, Petersen I, Treasure JL. The incidence of eating disorders in the 11 12 UK in 2000-2009: findings from the General Practice Research Database. BMJ Open 13 14 2013;3:e002646. 15 3 Hoek HW. Incidence, prevalence and mortality of anorexia nervosa and other eating 16 For peer review only 17 disorders. Curr Opin Psychiatry 2006;19:389–394. 18 19 4 Smink FRE, van Hoeken D, Hoek HW. Epidemiology of eating disorders: incidence, 20 21 prevalence and mortality rates. Current Psychiatry Reports 2012;14:406–414. 22 5 Currin L, Schmidt U, Treasure J, Jick H. Time trends in eating disorder incidence. Br J 23 24 Psychiatry 2005;186:132–135. 25 26 6 House J, Schmidt U, Craig M, et al. Comparison of specialist and nonspecialist care 27 pathways for adolescents with anorexia nervosa and related eating disorders. Int J Eat 28 29 Disord 2012;45:949–956. 30 31 7 Nicholls DE, Lynn R, Viner RM. Childhood eating disorders: British national 32 33 surveillance study. Br J Psychiatry 2011;98:295–301. http://bmjopen.bmj.com/ 34 8 Lask B, Bryant‐Waugh R, Wright F, Campbell M, Willoughby K, Waller G. Family 35 36 physician consultation patterns indicate high risk for early-onset anorexia nervosa. Int J 37 38 Eat Disord 2005;38:269–272. 39 40 9 Goodman R, Ford T, Simmons H, Gatward R, Meltzer H. Using the Strengths and 41 Difficulties Questionnaire (SDQ) to screen for child psychiatric disorders in a community on September 30, 2021 by guest. Protected copyright. 42 43 sample. Br J Psychiatry 2000;177:534–539. 44 45 10 National Institute for Health and Care Excellence. Eating disorders: recognition and 46 treatment. NICE guideline [NG69]. National Institute for Health and Care Excellence, 47 48 2017. 49 50 11 Byford S, Petkova H, Stuart R, et al. Cost-effectiveness of models of care for young 51 52 people with eating disorders (the CostED study). Health Service and Delivery Research 53 2018 (in press). 54 55 56 57 58 17 59 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 18 of 27 BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
1 2 3 12 Lynn RM, Viner RM, Nicholls DE. Ascertainment of early onset eating disorders: a pilot 4 5 for developing a national child psychiatric surveillance system. Child Adolesc Ment 6 7 Health 2012;17:109–112. 8 13 Knowles RL, Friend H, Lynn R, Mitchell S, Michie C, Ihekweazu C. Surveillance of rare 9 10 diseases: a public health evaluation of the British Paediatric Surveillance Unit. J Public 11 12 Health 2012;34:279–286. 13 14 14 American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders 15 (DSM–5), Fifth Edition. Washington DC: American Psychiatric Association, 2013. 16 For peer review only 17 15 Le Grange D, Doyle PM, Swanson SA, Ludwig K, Glunz K, Kreipe RE. Calculation of 18 19 expected body weight in adolescents with eating disorders. Pediatrics 2012;129:e438– 20 21 e446. 22 16 Gowers SG, Harrington RC, Whitton A, et al. Brief scale for measuring the outcomes of 23 24 emotional and behavioural disorders in children: Health of the Nation Outcome Scales for 25 26 Children and Adolescents (HoNOSCA). Br J Psychiatry 1999;174:413–416. 27 17 Shaffer D, Gould MS, Brasic J, et al. A children's global assessment scale (CGAS). Arch 28 29 Gen Psychiatry 1983;40:1228–1231. 30 31 18 Office for National Statistics. Population Estimates for UK, England and Wales, Scotland 32 33 and Northern Ireland. Office for National Statistics, 2015. http://bmjopen.bmj.com/ 34 19 Central Statistics Office for the Republic of Ireland. PEA11: Population estimates from 35 36 1926 by Single Year of Age, Sex and Year, 37 38 https://www.cso.ie/px/pxeirestat/Statire/SelectVarVal/Define.asp?maintable=PEA11&PL 39 40 anguage=0. 41 20 Hakulinen T, Dyba T. Precision of incidence predictions based on Poisson distributed on September 30, 2021 by guest. Protected copyright. 42 43 observations. Stat Med 1994;13:1513–1523. 44 45 21 Gowers S, Levine W, Bailey-Rogers S, Shore A, Burhouse E. Use of a routine, self- 46 report outcome measure (HoNOSCA-SR) in two adolescent mental health services. Br J 47 48 Psychiatry 2002;180:266–269. 49 50 22 Gowers SG, Clark A, Roberts C, et al. Clinical effectiveness of treatments for anorexia 51 52 nervosa in adolescents: Randomised controlled trial. Br J Psychiatry 2007;191:427–435. 53 54 55 56 57 58 18 59 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 19 of 27 BMJ Open BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
1 2 3 Table 1 Characteristics of incident cases 4 5 N Mean (SD) or % 6 7 Age 305 14.56 (1.66) 8 9 Sex 10 Female 279 91.48% 11 12 Male 26 8.52% 13 14 Ethnicity 15 Any White 274 91.64% 16 For peer review only 17 White and Asian 6 2.01% 18 19 White and Black Caribbean 2 0.67% 20 21 White and Black African 1 0.33% 22 Other Mixed 1 0.33% 23 24 Indian 3 1.00% 25 26 Pakistani 2 0.67% 27 28 Bangladeshi 1 0.33% 29 Other Asian 4 1.34% 30 31 Black Caribbean 2 0.67% 32 33 Chinese 1 0.33% http://bmjopen.bmj.com/ 34 Ethnicity not known 2 0.67% 35 36 Clinical status 37 38 BMI 304 16.50 (2.25) 39 40 % of median expected BMI 303 83.23 (10.99) 41 CGAS 280 44.61 (14.08) on September 30, 2021 by guest. Protected copyright. 42 43 HoNOSCA 63 19.40 (8.17) 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 19 59 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 20 of 27 BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
1 2 3 Table 2 Cases by region of the UK and Republic of Ireland 4 5 Incident Incident 6 Region Population N Population % * 7 cases N cases % 8 9 England 213 69.84% 6,194,444 77.83% 10 Scotland 44 14.43% 561,490 7.06% 11 12 Northern Ireland 41 13.44% 231,822 2.91% 13 14 Republic of Ireland 7 2.30% 628,251 7.89% 15 Wales 0 0.00% 342,627 4.31% 16 For peer review only 17 Total 305 7,958,634 18 19 * Does not sum to 100 due to rounding 20 21 22 23 24 25 26 27 28 29 30 31 32 33 http://bmjopen.bmj.com/ 34 35 36 37 38 39 40 41 on September 30, 2021 by guest. Protected copyright. 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 20 59 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 21 of 27 BMJ Open BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
1 2 3 Table 3 Annual incidence of anorexia nervosa in young people aged 8 to 17 for 2015, reported 4 5 per 100,000 young people 6 7 Observed rate IR0 Adjusted rate IR1 Adjusted rate IR2 8 9 Age IR 95% CI IR 95% CI IR 95% CI 10 8 0.18 0.01 to 0.76 0.43 0.10 to 1.14 0.57 0.18 to 1.35 11 12 9 0.18 0.01 to 0.77 0.44 0.11 to 1.17 0.58 0.18 to 1.38 13 14 10 0.19 0.01 to 0.80 0.45 0.11 to 1.21 0.60 0.19 to 1.43 15 11 1.53 0.79 to 2.67 3.65 2.43 to 5.25 4.85 3.43 to 6.65 16 For peer review only 17 12 4.91 3.47 to 6.76 11.69 9.39 to 14.38 15.56 12.89 to 18.63 18 19 13 8.39 6.44 to 10.73 19.95 16.89 to 23.42 26.58 23.02 to 30.54 20 21 14 11.71 9.41 to 14.39 27.85 24.25 to 31.84 37.10 32.92 to 41.66 22 15 12.39 10.05 to 15.10 29.47 25.80 to 33.52 39.25 35.50 to 43.88 23 24 16 12.76 10.42 to 15.47 30.37 26.70 to 34.41 40.45 36.19 to 45.07 25 26 17 6.03 4.47 to 7.96 14.35 11.88 to 17.19 19.12 16.24 to 22.35 27 28 Total 5.75 5.23 to 6.30 13.68 12.88 to 14.52 18.22 17.29 to 19.18 29 30 31 32 33 http://bmjopen.bmj.com/ 34 35 36 37 38 39 40 41 on September 30, 2021 by guest. Protected copyright. 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 21 59 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
BMJ Open Page 22 of 27
1 2 3 Table 4 Annual incidence of anorexia nervosa in young people aged 8 to 17 for 2015 by sex, reported per 100,000 young people 4 5 Observed incidence IR0 Adjusted incidence IR1 Adjusted incidence IR2 6 7 Age Female 95% CI Male 95% CI Female 95% CI Male 95% CI Female 95% CI Male 95% CI 8 8 0.36 0.02 to 1.55 0.00 0.00 to 0.00 0.87 0.21 to 2.34 0.00 0.00 to 0.00 1.16 0.36 to 2.76 0.00 0.00 to 0.00 9 10 9 0.00 0.00 to 0.00 0.35 0.02 to 1.52 0.00 0.00 to 0.00 0.85 0.21 to 2.28 0.00 0.00 to 0.00 1.13 0.35 to 2.69 11 10 0.39 0.02 to 1.65 0.00 0.00 to 0.00 0.93 0.23 to 2.48 0.00 0.00 to 0.00 1.23 0.39 to 2.93 0.00 0.00 to 0.00 12 For peer review only 13 11 2.35 1.07 to 4.46 0.75 0.15 to 2.18 5.59 3.47 to 8.51 1.77 0.71 to 3.63 7.44 4.96 to 10.72 2.37 1.11 to 4.42 14 12 8.05 5.43 to 11.50 1.92 0.80 to 3.86 19.17 14.98 to 24.16 4.56 2.69 to 7.22 25.53 20.66 to 31.21 6.09 3.89 to 9.08 15 16 13 16.36 12.48 to 21.06 0.78 0.16 to 2.28 38.93 32.81 to 45.86 1.85 0.75 to 3.79 51.83 44.72 to 59.74 2.47 1.16 to 4.62 17 18 14 22.35 17.83 to 27.67 1.53 0.56 to 3.32 53.19 46.08 to 61.10 3.64 2.00 to 6.07 70.84http://bmjopen.bmj.com/ 62.58 to 79.88 4.84 2.91 to 7.55 19 15 24.28 19.59 to 29.74 1.11 0.33 to 2.71 57.77 50.41 to 65.90 2.65 1.31 to 4.78 76.93 68.39 to 86.23 3.54 1.95 to 5.91 20 21 16 23.94 19.36 to 29.28 2.16 0.99 to 4.11 56.95 49.75 to 64.90 5.14 3.20 to 7.83 75.87 67.52 to 84.97 6.85 4.57 to 9.87 22 17 11.27 8.22 to 15.08 1.07 0.32 to 2.60 26.82 21.98 to 32.40 2.54 1.25 to 4.58 35.71 30.09 to 42.07 3.39 1.87 to 5.67 23 24 Total 10.78 9.77 to 11.87 0.96 0.68 to 1.30 25.66 24.09 to 27.30 2.28 1.84 to 2.79 34.17 32.36 to 36.06 3.03 2.52 to 3.62 25 26 on September 30, 2021 by guest. Protected copyright. 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 22 44 45 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Page 23 of 27 BMJ Open BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
1 2 3 Figure 1 Flow diagram of case ascertainment 4 5 6 7 8 9 10 11 12 13 14 15 16 For peer review only 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 http://bmjopen.bmj.com/ 34 35 36 37 38 39 40 41 on September 30, 2021 by guest. Protected copyright. 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 23 59 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 24 of 27 BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
1 2 3 4 Case notifications 5 n=997 6 7 8 9 Withdrew or excluded prior 10 to baseline data collection 11 n=48 12 13 14 15 No baseline data received 16 For peern=352 review only 17 18 19 20 21 Baseline questionnaire 22 received 23 n=597 24 25 26 27 Ineligible for study 28 inclusion 29 n=285 30 31 32 33 http://bmjopen.bmj.com/ Duplicate 34 n=7 35 36 37 38 39 Confirmed cases 40 41 n=305 on September 30, 2021 by guest. Protected copyright. 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 24 59 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 25 of 27 BMJ Open BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
1 2 3 Web extras 4 5 Case notification definition 6 7 Please report any child/young person aged 8 to 17 years and 11 months inclusive, who meets the 8 case notification definition criteria below for the first time in the last month. One bullet point 9 10 criterion from each group below should be fulfilled. 11 12 Group A 13 14 Restriction of food, low body weight, or 15 Weight less than expected for age 16 For peer review only 17 Group B 18 19 Fear of gaining weight, or 20 21 Fear of becoming fat, or 22 23 Behaviour that interferes with weight gain, for example excessive exercising, self- 24 induced vomiting, use of laxatives and diuretics 25 26 Group C 27 28 Body image disturbance, or 29 30 Persistent lack of recognition of the seriousness of the current low body weight 31 Exclusions 32 33 Patients who are not underweight http://bmjopen.bmj.com/ 34 35 Patients with bulimia nervosa, binge eating disorder, avoidant restrictive food intake 36 37 disorder or other failure to thrive presentations 38 39 40 41 on September 30, 2021 by guest. Protected copyright. 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 25 59 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 26 of 27 BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
1 2 STROBE Statement—Checklist of items that should be included in reports of cross-sectional studies 3 Item Page 4 No Recommendation No 5 Title and abstract 1 (a) Indicate the study’s design with a commonly used term in the 1 6 title or the abstract 7 b 8 ( ) Provide in the abstract an informative and balanced summary of 2 9 what was done and what was found 10 Introduction 11 Background/rationale 2 Explain the scientific background and rationale for the investigation 4 12 13 being reported 14 Objectives 3 State specific objectives, including any prespecified hypotheses 4 15 Methods 16 Study design For4 Presentpeer key elements review of study design early only in the paper 4-5 17 18 Setting 5 Describe the setting, locations, and relevant dates, including periods 4-5 19 of recruitment, exposure, follow-up, and data collection 20 Participants 6 (a) Give the eligibility criteria, and the sources and methods of 5, 7 21 selection of participants 22 Variables 7 Clearly define all outcomes, exposures, predictors, potential 6, 7 23 24 confounders, and effect modifiers. Give diagnostic criteria, if 25 applicable 26 Data sources/ 8* For each variable of interest, give sources of data and details of 6 27 measurement methods of assessment (measurement). Describe comparability of 28 assessment methods if there is more than one group 29 30 Bias 9 Describe any efforts to address potential sources of bias n/a 31 Study size 10 Explain how the study size was arrived at n/a – 32 population 33 level http://bmjopen.bmj.com/ 34 Quantitative variables 11 Explain how quantitative variables were handled in the analyses. If 8-10 35 36 applicable, describe which groupings were chosen and why 37 Statistical methods 12 (a) Describe all statistical methods, including those used to control 10 38 for confounding 39 (b) Describe any methods used to examine subgroups and n/a 40 interactions 41 on September 30, 2021 by guest. Protected copyright. c 42 ( ) Explain how missing data were addressed 8-9 43 (d) If applicable, describe analytical methods taking account of n/a 44 sampling strategy 45 (e) Describe any sensitivity analyses n/a 46 47 Results 48 Participants 13* (a) Report numbers of individuals at each stage of study—eg 10, 23 49 numbers potentially eligible, examined for eligibility, confirmed 50 eligible, included in the study, completing follow-up, and analysed 51 (b) Give reasons for non-participation at each stage 10, 23 52 53 (c) Consider use of a flow diagram 23 54 Descriptive data 14* (a) Give characteristics of study participants (eg demographic, 10-11, 19 55 clinical, social) and information on exposures and potential 56 confounders 57 (b) Indicate number of participants with missing data for each 19 58 59 1 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 27 of 27 BMJ Open BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
1 2 variable of interest 3 Outcome data 15* Report numbers of outcome events or summary measures n/a 4 Main results 16 (a) Give unadjusted estimates and, if applicable, confounder-adjusted 11, 21-22 5 estimates and their precision (eg, 95% confidence interval). Make 6 7 clear which confounders were adjusted for and why they were 8 included 9 (b) Report category boundaries when continuous variables were n/a 10 categorized 11 (c) If relevant, consider translating estimates of relative risk into n/a 12 13 absolute risk for a meaningful time period 14 Other analyses 17 Report other analyses done—eg analyses of subgroups and n/a 15 interactions, and sensitivity analyses 16 Discussion For peer review only 17 18 Key results 18 Summarise key results with reference to study objectives 12 19 Limitations 19 Discuss limitations of the study, taking into account sources of 12-13 20 potential bias or imprecision. Discuss both direction and magnitude 21 of any potential bias 22 Interpretation 20 Give a cautious overall interpretation of results considering 13, 12 23 24 objectives, limitations, multiplicity of analyses, results from similar 25 studies, and other relevant evidence 26 Generalisability 21 Discuss the generalisability (external validity) of the study results 13 27 Other information 28 29 Funding 22 Give the source of funding and the role of the funders for the present 15 30 study and, if applicable, for the original study on which the present 31 article is based 32 http://bmjopen.bmj.com/ 33 *Give information separately for exposed and unexposed groups. 34
35 36 Note: An Explanation and Elaboration article discusses each checklist item and gives methodological background and 37 published examples of transparent reporting. The STROBE checklist is best used in conjunction with this article (freely 38 available on the Web sites of PLoS Medicine at http://www.plosmedicine.org/, Annals of Internal Medicine at 39 http://www.annals.org/, and Epidemiology at http://www.epidem.com/). Information on the STROBE Initiative is 40 available at www.strobe-statement.org. 41 on September 30, 2021 by guest. Protected copyright. 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 2 60 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
Incidence of anorexia nervosa in young people in the United Kingdom and the Republic of Ireland: A national surveillance study ForJournal: peerBMJ Open review only Manuscript ID bmjopen-2018-027339.R1
Article Type: Research
Date Submitted by the 25-Mar-2019 Author:
Complete List of Authors: Petkova, Hristina; Institute of Psychiatry Psychology and Neuroscience, Health Service and Population Research Department Simic, Mima; South London and Maudsley NHS Foundation Trust Nicholls, Dasha; Imperial College London Ford, Tamsin; University of Exeter Prina, A.Matthew; Institute of Psychiatry Psychology and Neuroscience Stuart, Ruth; Institute of Psychiatry Psychology and Neuroscience, Health Service and Population Research Department Livingstone, Nuala; Queen's University Belfast Kelly, Grace; Queen's University Belfast Macdonald, Geraldine; University of Bristol Eisler, Ivan; South London and Maudsley NHS Foundation Trust
Gowers, Simon; University of Liverpool http://bmjopen.bmj.com/ Barrett, Barbara; Institute of Psychiatry Psychology and Neuroscience Byford, Sarah; Institute of Psychiatry Psychology and Neuroscience
Primary Subject Mental health Heading:
Secondary Subject Heading: Epidemiology
Eating disorders < PSYCHIATRY, Child & adolescent psychiatry < Keywords: on September 30, 2021 by guest. Protected copyright. PSYCHIATRY, EPIDEMIOLOGY, anorexia nervosa
For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 1 of 30 BMJ Open
1 2
3 Incidence of anorexia nervosa in young people in the United Kingdom and the Republic BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 of Ireland: A national surveillance study 6 7 Hristina Petkova, Institute of Psychiatry, Psychology & Neuroscience at King’s College 8 London (Research Fellow). 9 10 Mima Simic, South London and Maudsley NHS Foundation Trust (Consultant Child and 11 12 Adolescent Psychiatrist). 13 14 Dasha Nicholls, Imperial College London (Reader in Child and Adolescent Psychiatry). 15 Tamsin Ford, University of Exeter Medical School (Professor of Child and Adolescent 16 17 Psychiatry). 18 For peer review only 19 A. Matthew Prina, Institute of Psychiatry, Psychology & Neuroscience at King’s College 20 21 London (Senior Lecturer in Epidemiology). 22 Ruth Stuart, Institute of Psychiatry, Psychology & Neuroscience at King’s College London 23 24 (Research Assistant). 25 26 Nuala Livingstone, Queen’s University Belfast (Research Fellow). 27 Grace Kelly, Queen’s University Belfast (Research Fellow). 28 29 Geraldine Macdonald, University of Bristol (Professor of Social Work). 30 31 Ivan Eisler, South London and Maudsley NHS Foundation Trust (Professor of Family 32 33 Psychology and Family Therapy). 34 Simon Gowers, University of Liverpool (Professor of Adolescent Psychiatry). 35 36 Barbara Barrett, Institute of Psychiatry, Psychology & Neuroscience at King’s College
37 http://bmjopen.bmj.com/ 38 London (Senior Lecturer in Health Economics). 39 40 Sarah Byford, Institute of Psychiatry, Psychology & Neuroscience at King’s College London 41 (Professor of Health Economics). 42 43 44
45 Corresponding author: Sarah Byford, Institute of Psychiatry, Psychology & Neuroscience at on September 30, 2021 by guest. Protected copyright. 46 King’s College London, P024 David Goldberg Centre, De Crespigny Park, London SE5 8AF, 47 48 UK, [email protected], 02078480043 49 50 51 52 53 54 55 56 57 58 59 60
1 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 2 of 30
1 2
3 Abstract BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 Objectives: This study aimed to estimate the incidence of DSM5 anorexia nervosa in young 6 7 people in contact with child and adolescent mental health services in the UK and Republic of 8 Ireland. 9 10 Design: Observational, surveillance study using the Child and Adolescent Psychiatry 11 12 Surveillance System, involving monthly reporting by child and adolescent psychiatrists 13 st th 14 between 1 February 2015 and 30 September 2015. 15 Setting: UK and Republic of Ireland 16 17 Participants: Clinician-reported data on young people aged 8 to 17 in contact with child and 18 For peer review only 19 adolescent mental health services for a first episode of anorexia nervosa. 20 21 Main outcome measures: Annual incidence rates estimated as confirmed new cases per 22 100,000 population at risk. 23 24 Results: 305 incident cases of anorexia nervosa were reported over the 8-month surveillance 25 26 period and assessed as eligible for inclusion. The majority were young women (91%), from 27 England (70%), and of white ethnicity (92%). Mean age was 14.6 years (±1.66) and mean 28 29 percentage of median expected BMI for age and sex was 83.23% (±10.99%). The overall 30 31 incidence rate, adjusted for missing data, was estimated to be 13.68 per 100,000 population 32 33 (95% CI 12.88 to 14.52), with rates of 25.66 for young women (95% CI 24.09 to 27.30) and 34 2.28 for young men (95% CI 1.84 to 2.79). Incidence increased steadily with age, peaking at 35 36 15 for young women (57.77, 95% CI 50.41 to 65.90) and 16 for young men (5.14, 95% CI 3.20
37 http://bmjopen.bmj.com/ 38 to 7.83). Comparison with earlier estimates suggests incidence rates for children aged 13 and 39 40 under have increased over the last ten years. 41 Conclusions: These results provide up-to-date estimates of the incidence of anorexia nervosa 42 43 in young people. Service providers and commissioners should consider evidence to suggest 44
45 an increase in incidence in younger children. on September 30, 2021 by guest. Protected copyright. 46 Study registration: International Standard Randomised Controlled Trial Number Register 47 48 [ISRCTN12676087]. 49 50 51 52 Strengths and limitations of this study 53 This study provides up-to-date estimates of the incidence of anorexia nervosa in 54 55 young people aged 8 to 17 presenting to child and adolescent mental health services in 56 57 the UK and Republic of Ireland. 58 59 60
2 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 3 of 30 BMJ Open
1 2
3 The study benefits from a large, nationally representative sample from across the UK BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 and the Republic of Ireland. 6 7 Results were limited by missing data which was dealt with by adjusting observed 8 9 incidence rates using assumptions about incidence among missing cases. 10 Results are relevant to young people diagnosed with anorexia nervosa by child and 11 12 adolescent psychiatrists and not to those who are managed by general practitioners in 13 14 primary care or those who have not come to the attention of services, for example 15 16 those who choose not to seek help. 17 18 For peer review only 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
37 http://bmjopen.bmj.com/ 38 39 40 41 42 43 44
45 on September 30, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
3 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 4 of 30
1 2
3 What is already known on this topic BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 Estimates of the incidence of anorexia nervosa in the UK and Republic of Ireland are at least 6 7 ten years old. In addition, most estimates are derived from community-based primary care 8 9 records, which fail to accurately record all new cases, since cases may present to accident and 10 emergency and require immediate paediatric or psychiatric input, including inpatient 11 12 admission. Existing incidence data from secondary care settings in the UK are limited and no 13 14 data were identified for the Republic of Ireland. The only incidence study identified which 15 used secondary care data – a British national surveillance study – focused only on children 16 17 under 13 with data collected over ten years ago (2005-2006). 18 For peer review only 19 20 21 What this study adds 22 23 This study provides estimates of the incidence of DSM5 anorexia nervosa in young people 24 aged 8 to 17 years in contact with child and adolescent mental health services in the United 25 26 Kingdom and Republic of Ireland, which replace estimates that are over ten years old and 27 28 limited by age range or geographical coverage. The results suggest that overall incidence 29 30 rates have remained steady, but rates for young people under the age of 13 have increased 31 over time. Providing up-to-date incidence estimates and monitoring trends can help to 32 33 support health service planning for the provision of timely, effective and cost-effective 34 35 interventions. 36
37 http://bmjopen.bmj.com/ 38 39 40 41 42 43 44
45 on September 30, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
4 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 5 of 30 BMJ Open
1 2
3 Introduction BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 Anorexia nervosa is a serious and enduring eating disorder with high morbidity and the 6 1 7 highest mortality among psychiatric disorders. Young women are particularly susceptible, 8 with annual UK estimates of 37 new diagnoses of anorexia nervosa per 100,000 for girls aged 9 10 10 to 19 years, compared to 3 per 100,000 for boys of the same age.2 Prevalence estimates in 11 12 young people range from 0.3% to 0.6%.3–4 13 14 15 Accurate epidemiological estimates of the number of new anorexia nervosa cases per year 16 17 and their sex and age profile are needed for causal investigations and service planning.2 18 For peer review only 2,5–7 19 However, available estimates in the UK are at least ten years old. In addition, most 20 2,5 21 estimates are derived from community-based primary care records, which fail to accurately 22 record all new cases.8,9 Undetected anorexia nervosa cases may present to accident and 23 24 emergency and require immediate paediatric or psychiatric input, including inpatient 25 26 admission. Some young people may therefore bypass primary care and, consistent with UK 27 guidelines,10 are likely to be assessed and diagnosed by a child and adolescent psychiatrist in 28 29 a secondary care setting, making secondary care records a more reliable source of data on 30 31 anorexia nervosa incidence than primary care registers. 32 33 34 Existing incidence data from secondary care settings in the UK are limited. One study, 35 36 focusing only on adolescents aged 13 to 18, was limited to Greater London and reported
37 http://bmjopen.bmj.com/ 38 presentation rates to child and adolescent mental health services (CAMHS), rather than 39 6 40 incidence estimates. A second study, which used a national surveillance design, focused only 41 on children under 13.7 The current study aimed to estimate the incidence of anorexia nervosa 42 43 in secondary care services for young people between the ages of 8 and 17 years in the UK 44
45 and the Republic of Ireland. This work formed part of a study exploring the cost- on September 30, 2021 by guest. Protected copyright. 46 effectiveness of models of care for young people with eating disorders (the CostED study).11 47 48 49 50 Methods 51 52 Design 53 An observational, surveillance study was undertaken using the Child and Adolescent 54 55 Psychiatry Surveillance System (CAPSS). CAPSS is a system designed to ascertain cases of 56 57 rare childhood mental health conditions in the UK and Republic of Ireland through monthly 58 reporting by clinicians and relies on non-consent to maximise the accuracy of 59 60
5 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 6 of 30
1 2
3 epidemiological estimates. The CAPSS system has been operating since 200912 and is based BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 on the well-established British Paediatric Surveillance Unit (BPSU) system.13 6 7 8 The study was approved by the CAPSS Executive Committee, King’s College London 9 10 Research Ethics Committee [PNM/13/14-105], and the Health Research Authority 11 12 Confidentiality Advisory Group [CAG 4-03(PR1)/2014] under Section 251 of the NHS Act 13 14 2006, which enables disclosure of confidential patient information for purposes where it is 15 not possible to use anonymised information and where seeking consent is not practical. 16 17 18 For peer review only 19 Inclusion and exclusion criteria 20 21 The study included young people between 8 and 17 years of age, in contact with CAMHS for 22 a first episode of anorexia nervosa according to DSM5 diagnostic criteria.14 Anorexia 23 24 nervosa is exceptionally rare in children under 8 and the cut-off at 17 was due to the focus on 25 26 young people in contact with CAMHS, with many young people transitioning to adult 27 services at the age of 18. New cases were notified for a period of eight months from 1st 28 29 February to 30th September 2015. Cases whose clinician-reported data were insufficient to 30 31 assess eligibility were excluded, as were duplicate cases notified more than once by the same 32 33 or different clinicians. 34 35 36 Procedures
37 http://bmjopen.bmj.com/ 38 At the time of the study, CAPSS used a report card, known as the yellow card, containing a 39 40 list of conditions being surveyed. Yellow cards, along with reporting instructions and 41 protocols for new studies, are sent monthly from the CAPSS office to a mailing list of all 42 43 hospital, university and community child and adolescent consultant psychiatrists across the 44
45 United Kingdom and the Republic of Ireland. Reporting clinicians are asked to check boxes on September 30, 2021 by guest. Protected copyright. 46 against any of the reportable conditions they have seen in the preceding month, or to check a 47 48 "nil return" box and return the card to CAPSS. A tear-off slip is provided for respondents to 49 50 keep a record of the patients reported. "Positive" returns are allocated a unique CAPSS ID 51 52 number and notified to the appropriate research investigator, who then contacts the reporting 53 clinician directly to request completion of a questionnaire using the CAPSS ID to enable the 54 55 clinician to identify the relevant patient. 56 57 58 For the CostED study, the yellow card contained a check box for anorexia nervosa and was 59 60 sent to clinicians along with a protocol card detailing the case notification definition for
6 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 7 of 30 BMJ Open
1 2
3 anorexia nervosa. The case notification definition (see web extras) was based on DSM5 BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 diagnostic criteria for anorexia nervosa and was intended to aid clinicians in their decision to 6 7 tick “yes” or “no” on the yellow card. It was not intended to identify whether a case met 8 study inclusion criteria, which was determined by the research group after receipt of all 9 10 necessary data. 11 12 13 14 Data 15 Questionnaires were sent to clinicians who reported a positive case of anorexia nervosa, 16 17 identified via the unique CAPSS ID number. Questionnaires were completed from clinical 18 For peer review only 19 records and clinicians were asked to provide data relating to the time the case was initially 20 21 assessed and diagnosed. The questionnaire covered clinical features to enable assessment of 22 case eligibility, referral pathway information to ensure assessment and diagnosis had not 23 24 happened prior to the study surveillance period, and a limited set of standard patient 25 26 identifiers in line with CAPSS procedures and ethics requirements, which were used to 27 describe the sample and to identify duplicate notifications. In addition, clinicians were asked 28 29 to confirm whether the case was a first episode of anorexia nervosa that had come to the 30 31 attention of services. 32 33 34 The patient identifiers included NHS or Community Health Index (CHI) number (unique 35 36 patient identifiers used in the regions of interest), hospital number, first half of postcode or
37 http://bmjopen.bmj.com/ 38 town of residence for the Republic of Ireland, sex, date of birth and ethnicity (White, Mixed, 39 40 Asian, Black, Chinese, Other or Unknown). In Northern Ireland, identifiers were limited to 41 age in years and months and hospital identifier rather than hospital number, to reduce the risk 42 43 of patient identification given the small geographic area. All patient identifiable data from 44
45 Northern Ireland were retained by the local research team, de-duplicated, anonymised and on September 30, 2021 by guest. Protected copyright. 46 subsequently sent to the central research team in King’s College London for analysis as per 47 48 requirements set out by the Northern Ireland Privacy Advisory Committee. All data storage 49 50 was compliant with the EU General Data Protection Regulations. 51 52 53 Clinical features included: weight and height to calculate body mass index (BMI) and 54 55 percentage of median expected BMI for age and sex interpreted around the 85% threshold;15 56 16 57 the Health of the Nation Outcome Scales for Children and Adolescents (HoNOSCA ), a 58 routine outcome measure rating 13 clinical features on a five-point severity scale including 59 60 behaviours, impairments, symptoms, and social functioning of children and adolescents with
7 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 8 of 30
1 2
3 mental health problems; the clinician completed Children's Global Assessment Scale BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 (CGAS17) used to rate emotional and behavioural functioning of young people; and a range of 6 7 symptoms relating to the diagnosis of anorexia nervosa. 8 9 10 Unreturned or incomplete questionnaires were chased via email and telephone. Cases where 11 12 any symptom required for case definition was absent despite chasing, were assessed for 13 14 eligibility by a consultant child and adolescent psychiatrist (MS). 15 16 17 Case eligibility 18 For peer review only 19 Cases were assessed as eligible for the study if: (a) they were between 8 and 17 years of age; 20 21 (b) they had no previous episode of anorexia nervosa that had come to the attention of 22 services; (c) they received a clinical assessment in the reporting service during the study 23 24 surveillance period; (d) they had not been referred from another secondary health service (to 25 26 ensure assessment and diagnosis had not happened prior to study surveillance period); and (e) 27 the following clinical symptoms were present: “Restriction of energy intake relative to 28 29 requirements” and “Persistent behaviour that interferes with weight gain, despite low 30 31 weight”. This broad definition was subsequently checked using a tighter DSM5 analytic 32 33 definition including the following symptoms: 34 1) “Restriction of energy intake relative to requirements” and 35 36 2) “Intense fear of gaining weight or of becoming fat” or “Persistent behaviour that
37 http://bmjopen.bmj.com/ 38 interferes with weight gain, despite low weight” and 39 40 3) “Perception that body shape/size is larger than it is” or “Preoccupation with body 41 weight and shape” or “Lack of recognition of the seriousness of the current low body 42 43 weight” 44
45 Only one case which met the broad criteria failed to meet the tighter criteria, thus confirming on September 30, 2021 by guest. Protected copyright. 46 the validity of the broad criteria. 47 48 49 50 Removal of duplicates 51 52 Duplicates were identified by comparing NHS/CHI numbers, hospital numbers/ hospital 53 identifiers and date of birth/age in years and months, as appropriate. The management of 54 55 duplicates depended upon the outcome for the original notification for which a duplicate was 56 57 identified. Four scenarios were considered: (1) duplicates where the original notification met 58 study inclusion criteria were excluded and the original retained; (2) duplicates where the 59 60 original notification had been excluded because the young person was under 8 years of age or
8 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 9 of 30 BMJ Open
1 2
3 did not meet the clinical criteria were assessed as a new case to determine if the case now met BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 eligibility criteria; (3) duplicates where the original notification was excluded due to a 6 7 previous episode of anorexia nervosa, a diagnosis date prior to the study surveillance period 8 or referral from another secondary care service, were excluded; and (4) duplicates where the 9 10 original notification contained insufficient information to judge eligibility were checked to 11 12 see if the duplicate contained the missing information and, if available, the original 13 14 notification was reassessed for eligibility and the duplicate managed as per the scenarios 15 above. 16 17 18 For peer review only 19 Data analysis 20 21 Data analysis was performed using Stata IC v14.2 and Microsoft Excel 2010. Observed 22 incidence rates (denoted IR0), defined as the number of new cases during a specified period 23 24 of time in a population at risk for developing the disease, were calculated as follows: the 25 26 number of confirmed new cases of anorexia nervosa in the 8-month surveillance period 27 converted to 12 months [(N cases over 8 months/8)*12], divided by the population at risk and 28 29 multiplied by 100,000 to give the rate per 100,000 young people. 30 31 32 33 IR0 = (confirmed new cases converted to 12 months)/the population at risk *100,000 34 35 36 The population at risk was calculated as the total number of children of each year of age and
37 http://bmjopen.bmj.com/ 38 each sex in the UK and Republic of Ireland minus the number of prevalent cases who, once 39 40 diagnosed, are no longer part of the “at risk” population. Population data for 2015 were 41 obtained from the Office for National Statistics for the UK18 and the Central Statistics Office 42 43 for the Republic of Ireland.19 To estimate the number of prevalent cases each year, incident 44
45 cases in the previous age band were used as a proxy. For example, incident cases aged eight on September 30, 2021 by guest. Protected copyright. 46 were used as a proxy for prevalent cases in the estimation of the ‘at risk’ population aged 47 48 nine, and so on. 49 50 51 52 To consider incidence among unobserved missing cases, adjustments were needed for 53 unreturned CAPSS notification cards and questionnaires. For CAPSS notification cards, just 54 55 over half of all notification cards sent out were returned (50.16%). To account for incidence 56 57 among the 49.84% of unreturned cards, two assumptions were made, and an appropriate 58 correction applied to IR0, the observed incidence rate: 59 60
9 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 10 of 30
1 2
3 Assumption 1: To take into consideration the possibility that unreturned cards are more likely BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 to be ‘nil’ returns, it was assumed that half of unreturned cards (24.92%) were ‘negative’ and 6 7 half followed the same proportion of ‘negative’ and ‘positive’ as the returned cards. This 8 assumption translates into a correction coefficient of 1.50 derived from (24.92+50.16)/50.16. 9 10 11 12 Assumption 2: Making no assumptions of bias in the likelihood of unreturned cards being 13 14 either positive or negative returns, it was assumed that all unreturned cards followed the same 15 proportion of ‘negative’ and ‘positive’ as returned cards. This assumption translates into a 16 17 correction coefficient of 1.99 derived from (49.84+50.16)/50.16. 18 For peer review only 19 20 21 These assumptions provide a range of incidence rates, from a minimum (observed incidence 22 rate) to a maximum (assumption 2), within which the actual rate is likely to fall. We 23 24 hypothesised that assumption 1 provides the most realistic estimate since it assumes a bias in 25 26 the response rates with greater likelihood that unreturned cards are negative (‘nil’ returns) but 27 does not assume all unreturned cards are ‘nil’ returns, which is the implicit assumption within 28 29 IR0. 30 31 32 33 For unreturned questionnaires, approximately two-thirds of the questionnaires that were sent 34 to clinicians reporting positive cases of anorexia nervosa were returned (63%), leaving one- 35 36 third (37%) unreturned. Since all these questionnaires relate to a ‘positive’ notification, we
37 http://bmjopen.bmj.com/ 38 applied a correction coefficient of 1.59 derived from (37+63)/63, which assumes that the 39 40 incidence rate for the unreturned questionnaires is the same as the incidence rate identified in 41 the returned questionnaires for each year of age. 42 43 44
45 We then combined the correction coefficients described above, to generate two adjusted on September 30, 2021 by guest. Protected copyright. 46 incidence rates: 47 48 49 50 Adjusted incidence rate 1 (IR1) = Confirmed new cases of anorexia nervosa converted to 12 51 52 months, multiplied by the correction for unreturned CAPSS notification cards under 53 assumption 1, multiplied by the correction for unreturned questionnaires, then divided by the 54 55 population at risk and multiplied by 100,000. 56 57 58 IR1 = (confirmed new cases converted to 12 months * 1.50 * 1.59)/the population at risk 59 60 *100,000
10 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 11 of 30 BMJ Open
1 2
3 BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 Adjusted Incidence rate 2 (IR2) = Confirmed new cases of anorexia nervosa converted to 12- 6 7 months, multiplied by the correction for unreturned CAPSS notification cards under 8 assumption 2, multiplied by the correction for unreturned questionnaires and then divided by 9 10 the population at risk and multiplied by 100,000. 11 12 13 14 IR2 = (confirmed new cases converted to 12 months * 1.99 * 1.59)/the population at risk * 15 100,000 16 17 18 For peer review only 19 For each incidence rate, IR0, IR1 and IR2, total, age-specific and sex-specific annual 20 21 incidence rates for anorexia nervosa for the year 2015 and 95% confidence intervals were 22 calculated based on the Poisson distribution20 using the Stata command ci means [N new 23 24 anorexia nervosa cases 12m], Poisson [exposure(total population)] for positive 25 26 integers/whole incidence numbers (Stata interprets any non-integer decimal point number 27 between 0 and 1 as the fraction of events and converts it to an integer number). Annual 28 29 incidence rates were stratified by discrete age and sex. 30 31 32 33 Public and patient involvement statement 34 The CostED study included a patient and a parent representative on the study steering 35 36 committee who contributed to the design, conduct and management of the study, including
37 http://bmjopen.bmj.com/ 38 the incidence component. 39 40 41 Results 42 43 Case ascertainment 44
45 Case ascertainment is outlined in Figure 1. Over the eight-month surveillance period, 6401 on September 30, 2021 by guest. Protected copyright. 46 yellow cards were sent to reporting clinicians and 3211 were returned (50%). Of these, 997 47 48 positive cases of anorexia nervosa were reported and 2214 were nil returns. Of the positive 49 50 cases, 48 (5%) were excluded due to clinicans stating that they did not wish to be included in 51 52 the study (due to retirement, shortage of reporting capacity etc.) or due to reporting errors. 53 Questionnaires were sent to the remaining 949, and a further 352 positive cases (37%) were 54 55 excluded as they failed to return the questionnaires, so no data were available to assess 56 57 eligibility. Questionnaires were completed and returned for 597 notified cases, of which 292 58 (49%) were ineligible for reasons related to age, previous episode of anorexia nervosa, date 59 60 of assessment outside the study’s surveillance period, referral from another secondary care
11 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 12 of 30
1 2
3 service, insufficient information to assess diagnosis or duplicate notifications, leaving 305 BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 incident cases of anorexia nervosa as the sample for analysis. 6 7 8 Demographics and clinical features 9 10 Of the 305 young people identified as having DSM5 anorexia nervosa, the majority were 11 12 girls (91%), from England (70%) and of white ethnicity (92%) (see Table 1). The mean age 13 14 was 14.6 years (±1.66). Clinical variables suggest these young people were significantly 15 impaired. Mean BMI was 16.50 kg/m2 (±2.25), where values of 16.00 to 16.99 suggesting 16 17 moderate severity of anorexia nervosa. Mean percentage of median expected BMI for age and 18 For peer review only 19 sex (the deviation from expected body weight) was 83.23% (±10.99%), falling within the 20 21 range required for a diagnosis of anorexia nervosa (<85%). Mean CGAS score was 44.61 22 (±14.08), which falls within the range for ‘obvious problems’ (41–50) on a scale from 1 to 23 24 100 (1 being the worst and 100 the best emotional and behavioural functioning). Mean total 25 26 HoNOSCA score was 19.40 (±8.17) on a scale from 0 to 52, indicative of a severity similar to 27 that at inpatient admission.21,22 28 29 30 31 The proportion of the included sample notified from each region within the British Isles is 32 33 reported in Table 2, alongside the population of young people in each region by age. England 34 has the largest population (78%) and notified 70% of new cases. Scotland, containing only 35 36 7% of the total population, notified 14% of the sample and Northern Ireland, containing only
37 http://bmjopen.bmj.com/ 38 3% of the population, notified 13% of the sample. By contrast, the Republic of Ireland 39 40 notified only 2% of cases, despite containing 8% of the population, and Wales notified no 41 eligible cases (some cases were notified but did not meet inclusion criteria), despite 42 43 containing 4% of the population. 44
45 on September 30, 2021 by guest. Protected copyright. 46 Incidence rates 47 48 Table 3 details observed incidence rates (IR0) and adjusted incidence rates (IR1 and IR2) by 49 50 age. Incidence rates for the total sample ranged from a minimum of 5.75 per 100,000 young 51 52 people (95% CI 5.23 to 6.30; IR0) to a maximum of 18.22 per 100,000 young people (95% 53 CI 17.29 to 19.18; IR2), with IR1, the rate hypothesised to be the most accurate, falling 54 55 between these two values at 13.68 per 100,000 population (95% CI 12.88 to 14.52). Focusing 56 57 on IR1 rates, total incidence increased steadily with age, peaking at 16 (30.37, 95% CI 26.70 58 to 34.41), with a substantial drop at the age of 17 (14.35, 95% CI 11.88 to 17.19). 59 60
12 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 13 of 30 BMJ Open
1 2
3 Table 4 reports incidence rates by age and sex. Incidence among young men followed a BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 similar pattern to overall incidence rates reported in Table 3, being highest at the age of 16 6 7 (5.14) and half that at age 17 (2.54). The highest incidence among young women was seen a 8 year earlier than for boys, at the age of 15 (57.77), with similar rates at age 16 (56.95), 9 10 dropping by more than half at age 17 (26.82). 11 12 13 14 Discussion 15 Principal findings 16 17 This study provides up-to-date estimates of incident cases of anorexia nervosa in young 18 For peer review only 19 people aged 8 to 17 presenting to CAMHS services in the UK and Republic of Ireland. Our 20 21 mid-range, missing data-adjusted estimate (IR1) of the incidence of anorexia nervosa in the 22 full sample of young people aged 8 to 17 years was approximately 14 per 100,000. 23 24 25 26 Comparison with other studies 27 This result is lower than previous primary care-based estimates of 18–20 per 100,000 28 29 focusing on young people aged 10–19.2,5 This difference is due to the different age ranges in 30 31 the studies; the inclusion of children as young as 8 in the current study, who have relatively 32 33 low incidence, and exclusion of adolescents aged 18 to 19, whose incidence is relatively high, 34 makes the results difficult to compare. However, comparing rates for 10 to 14-year olds, 35 36 available in both studies, produces similar incidence rates, with rates of 12.6 per 100,000 in
37 http://bmjopen.bmj.com/ 38 the current study, compared to 13.1 per 100,000 in 2009.2 For females, the rates are 23.3 per 39 40 100,000 in the current study compared to 24.0 per 100,000 in 2009 and for males, 2.4 and 2.5 41 per 100,000, respectively. However, this comparison should be treated with caution given the 42 43 very different settings – primary care versus secondary care. 44
45 on September 30, 2021 by guest. Protected copyright. 46 Existing secondary care estimates of the incidence of anorexia nervosa in the UK are limited 47 48 to children under the age of 13, with an overall incidence of 1.09 per 100,000 reported for 49 50 children aged between 6 and 13 between 2005 and 2006.7 The methodology for this study was 51 52 very similar to the CostED methodology, using the CAPSS system but additionally the British 53 Paediatric Surveillance System. For comparison with the current study, the incidence rate for 54 55 children between 8 and 13 was approximately 1.5 per 100,000 for DSMIV anorexia nervosa or 56 57 1.8 per 100,000 for DSMIV anorexia nervosa plus ‘other eating disorders’ likely to contain 58 cases that would now be classified as anorexia nervosa using DSM5. This compares to a rate 59 60 of 5.83 per 100,000 in the current study for children of the same age. This estimate is
13 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 14 of 30
1 2
3 substantially higher than the 2006 estimates suggesting that incidence rates for younger BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 children have increased over time. 6 7 8 The results presented are also supported by international evidence. One study carried out in 9 10 Italy demonstrated a significant reduction in age at onset for anorexia nervosa in consecutive 11 12 outpatient referrals between 1985 and 2008 (n=1,666).23 A second study exploring time trends 13 14 in the incidence of anorexia nervosa, which was carried out using data from the Norwegian 15 National Patient Register, found overall rates of anorexia nervosa to be stable between 2010 16 17 and 2016 for the sample as a whole, but increasing for young females aged between 10 and 18 For peer review only 19 14.24 20 21 22 Strengths and weaknesses of the study 23 24 The large, nationally representative sample of this study is a strength. The study included 25 26 young people with anorexia nervosa, diagnosed using DSM5 criteria, from across the UK and 27 the Republic of Ireland and thus avoided biases inherent in studying clinical samples via a 28 29 small number of centres in a limited number of geographical areas. The results are of 30 31 relevance primarily to the UK and Republic of Ireland but may be of value to other high- 32 33 income countries. 34 35 36 With only a 50% response rate from CAPSS clinicians and a third of questionnaires not
37 http://bmjopen.bmj.com/ 38 returned, missing data were a major constraint. There are many reasons why clinicians may 39 40 fail to return notification cards or questionnaires, including changes in place of employment, 41 competing priorities, or the belief that cases will be reported by a colleague.13 This problem 42 43 was addressed by adjusting the observed incidence rates using assumptions about incidence 44
45 among both missing case notifications and missing questionnaires. on September 30, 2021 by guest. Protected copyright. 46 47 48 The methodology is also limited to young people seen by child and adolescent psychiatrists. 49 50 Cases that would not be identified by this methodology include those who have not come to 51 52 the attention of services, for example those who choose not to seek help, those managed by 53 general practitioners in primary care, and those in the care of mental health services without 54 55 psychiatric input, such as nurse-led facilities. This latter concern was an issue in Northern 56 57 Ireland where, due to initial low numbers of notifications, investigation by the research team 58 identified a number of nurse-led facilities which were invited to contribute, and subsequently 59 60 reported just over half of all cases in Northern Ireland. In terms of missing primary care
14 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 15 of 30 BMJ Open
1 2
3 cases, given UK guidelines for assessment and diagnosis of anorexia nervosa to be carried BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 out by child and adolescent psychiatrists in secondary care settings,10 it is reasonable to 6 7 assume that many of those cases remaining in primary care would not meet criteria for DSM5 8 anorexia nervosa. It is also possible that current inpatient cases are under-represented; 9 10 although notifications were sent to all child and adolescent psychiatrists, including those 11 12 working in inpatient settings, the main focus of the CostED study was the evaluation of 13 14 community-based services, and so clinicians may have mistakenly focused on notification of 15 community-based cases. 16 17 18 For peer review only 19 It must also be borne in mind that service-level (rather than population-level) incidence rates 20 21 are sensitive to external factors, including service availability, funding and commissioning 22 decisions, parental and school awareness, stigma, etc., all of which will impact upon observed 23 24 trends in incidence rates over time. The nature of community-based eating disorders services 25 26 for children and adolescents in England has started to change following the publication of 27 commissioning standards in June 2015,25 as well as investment of £30 million to support the 28 29 development of these services. This is unlikely to have had an impact on the CostED study 30 31 data because the first allocation of funding to services was made in 2016, after the end of the 32 33 CostED study surveillance period in 2015. However, these initiatives are likely to result in 34 increases in observed incidence rates in the future. 35 36
37 http://bmjopen.bmj.com/ 38 Meaning of the study 39 40 These results provide up-to-date estimates of the incidence of anorexia nervosa in young 41 people. Whilst firm conclusions relating to changes in incidence rates over time for the entire 42 43 sample cannot be drawn due to lack of existing secondary care evidence, service providers 44
45 and commissioners should consider evidence to suggest an increase in incidence in younger on September 30, 2021 by guest. Protected copyright. 46 children. 47 48 49 50 Unanswered questions and future research 51 52 Future research should explore the development of earlier interventions, given evidence of an 53 increase in incidence in young children suggesting that onset of anorexia nervosa may be 54 55 starting earlier for some young people than suggested by previous research. Research is also 56 57 needed to identify approaches to the assessment of incidence simultaneously in primary and 58 secondary care. Multinational studies should be considered for better assessment and 59 60 exploration of incidence rates in young men.
15 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 16 of 30
1 2
3 BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 Word count 6 7 4089 8 9 10 Acknowledgements 11 12 We would like to thank all the clinicians who were kind enough to give up their time to 13 14 provide the CostED study with CAPSS notifications and to complete questionnaires. We 15 know your time is precious and in short supply and we are truly grateful. We would also like 16 17 to thank the team at the Child and Adolescent Psychiatry Surveillance System, based at the 18 For peer review only 19 Royal College of Psychiatrist’s Centre for Care Quality and Improvement, for their support 20 21 with the design and running of the surveillance aspect of this study, and the study steering 22 committee for their invaluable advice. 23 24 25 26 Contributor and guarantor information 27 Hristina Petkova contributed to data collection, data entry, data cleaning, data analysis, and 28 29 drafting of the manuscript. 30 31 Mima Simic was a co-applicant, contributed to the design of the study, provided clinical 32 33 expertise, and commented on and approved the manuscript. 34 Dasha Nicholls was a co-applicant, contributed to the design of the study, provided expertise 35 36 on CAPSS methodology, clinical expertise, and commented on and approved the manuscript.
37 http://bmjopen.bmj.com/ 38 Tamsin Ford was a co-applicant, contributed to the design of the study, provided clinical 39 40 expertise, and commented on and approved the manuscript. 41 Matthew Prina contributed to the data analysis and commented on and approved the 42 43 manuscript. 44
45 Ruth Stuart contributed to data collection, data entry, data cleaning and data analysis, and on September 30, 2021 by guest. Protected copyright. 46 commented on and approved the manuscript. 47 48 Nuala Livingstone contributed to data collection, data entry and data management in 49 50 Northern Ireland, and commented on and approved the manuscript. 51 52 Grace Kelly contributed to data collection, data entry and data management in Northern 53 Ireland, and commented on and approved the manuscript. 54 55 Geraldine Macdonald contributed to the design of the study, managed the Northern Ireland 56 57 research staff, and commented on and approved the final report. 58 Ivan Eisler was a co-applicant, contributed to the design of the study, provided clinical 59 60 support to the research team, and commented on and approved the manuscript.
16 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 17 of 30 BMJ Open
1 2
3 Simon Gowers was a co-applicant, contributed to the design of the study, provided clinical BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 expertise, and commented on and approved the manuscript. 6 7 Barbara Barrett was a co-applicant, contributed to the design of the study, the data analysis, 8 and commented on and approved the manuscript. 9 10 Sarah Byford was principal investigator, led the study, managed the King’s College London 11 12 research staff, contributed to the design of the study and the data analysis, drafted the paper, 13 14 and is responsible for the overall content as guarantor. 15 16 17 Competing interests 18 For peer review only 19 Tamsin Ford reports she is Chair of the Child and Adolescent Psychiatry Surveillance Service 20 21 that was used to run part of the study, which is an unpaid position (other than travel 22 expenses). Kandarp Joshi reports that he was principal investigator for the Aberdeen site for a 23 24 Sunovion sponsored multisite trial on effectiveness of Lurasidone in paediatric schizophrenia. 25 26 No other authors report conflicts of interest. 27 28 29 Transparency statement 30 31 The lead author affirms that this manuscript is an honest, accurate, and transparent account of 32 33 the study being reported; that no important aspects of the study have been omitted; and that 34 any discrepancies from the study as planned and registered have been explained. 35 36
37 http://bmjopen.bmj.com/ 38 Role of the funding source 39 40 The study was funded by the NIHR Health Service & Delivery Research programme 41 (11/1023/17). The study funders had no role in the study design, the collection, analysis or 42 43 interpretation of data, the writing of the report, or the decision to submit the article for 44
45 publication. The authors were independent from the funders and all authors had full access to on September 30, 2021 by guest. Protected copyright. 46 all of the data in the study and can take responsibility for the integrity of the data and the 47 48 accuracy of the data analysis. 49 50 51 52 Disclaimer 53 The views expressed are those of the authors and not necessarily those of the NHS, the NIHR 54 55 or the Department of Health and Social Care. 56 57 58 59 60
17 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 18 of 30
1 2
3 Data sharing BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 As a result of the collection of confidential patient data without consent, and approval from 6 7 the Health Research Authority (following advice from the Confidentiality Advisory Group) 8 for data to be provided for the purposes of the specified activity only, the data cannot be 9 10 made publicly available for other purposes. However, the CostED research group will 11 12 consider requests for further analysis on a case by case basis, subject to appropriate 13 14 ethical/HRA CAG approvals. All data enquiries should be submitted to the corresponding 15 author for consideration in the first instance. 16 17 18 For peer review only 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
37 http://bmjopen.bmj.com/ 38 39 40 41 42 43 44
45 on September 30, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
18 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 19 of 30 BMJ Open
1 2
3 References BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 1 Arcelus J, Mitchell AJ, Wales J, Nielsen S. Mortality rates in patients with anorexia 6 7 nervosa and other eating disorders: A meta-analysis of 36 Studies. Arch Gen 8 Psychiatry 2011;68:724–731. 9 10 2 Micali N, Hagberg KW, Petersen I, Treasure JL. The incidence of eating disorders in 11 12 the UK in 2000-2009: findings from the General Practice Research Database. BMJ 13 14 Open 2013;3:e002646. 15 3 Hoek HW. Incidence, prevalence and mortality of anorexia nervosa and other eating 16 17 disorders. Curr Opin Psychiatry 2006;19:389–394. 18 For peer review only 19 4 Smink FRE, van Hoeken D, Hoek HW. Epidemiology of eating disorders: incidence, 20 21 prevalence and mortality rates. Current Psychiatry Reports 2012;14:406–414. 22 5 Currin L, Schmidt U, Treasure J, Jick H. Time trends in eating disorder incidence. Br 23 24 J Psychiatry 2005;186:132–135. 25 26 6 House J, Schmidt U, Craig M, et al. Comparison of specialist and nonspecialist care 27 pathways for adolescents with anorexia nervosa and related eating disorders. Int J Eat 28 29 Disord 2012;45:949–956. 30 31 7 Nicholls DE, Lynn R, Viner RM. Childhood eating disorders: British national 32 33 surveillance study. Br J Psychiatry 2011;98:295–301. 34 8 Lask B, Bryant‐Waugh R, Wright F, Campbell M, Willoughby K, Waller G. Family 35 36 physician consultation patterns indicate high risk for early-onset anorexia nervosa. Int
37 http://bmjopen.bmj.com/ 38 J Eat Disord 2005;38:269–272. 39 40 9 Goodman R, Ford T, Simmons H, Gatward R, Meltzer H. Using the Strengths and 41 Difficulties Questionnaire (SDQ) to screen for child psychiatric disorders in a 42 43 community sample. Br J Psychiatry 2000;177:534–539. 44
45 10 National Institute for Health and Care Excellence. Eating disorders: recognition and on September 30, 2021 by guest. Protected copyright. 46 treatment. NICE guideline [NG69]. National Institute for Health and Care Excellence, 47 48 2017. 49 50 11 Byford S, Petkova H, Stuart R, et al. Alternative community-based models of care for 51 52 young people with anorexia nervosa: the CostED national surveillance study. Health 53 Service and Delivery Research 2019 (in press). 54 55 12 Lynn RM, Viner RM, Nicholls DE. Ascertainment of early onset eating disorders: a 56 57 pilot for developing a national child psychiatric surveillance system. Child Adolesc 58 59 Ment Health 2012;17:109–112. 60
19 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 20 of 30
1 2
3 13 Knowles RL, Friend H, Lynn R, Mitchell S, Michie C, Ihekweazu C. Surveillance of BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 rare diseases: a public health evaluation of the British Paediatric Surveillance Unit. J 6 7 Public Health 2012;34:279–286. 8 14 American Psychiatric Association. Diagnostic and Statistical Manual of Mental 9 10 Disorders (DSM–5), Fifth Edition. Washington DC: American Psychiatric 11 12 Association, 2013. 13 14 15 Le Grange D, Doyle PM, Swanson SA, Ludwig K, Glunz K, Kreipe RE. Calculation 15 of expected body weight in adolescents with eating disorders. Pediatrics 16 17 2012;129:e438–e446. 18 For peer review only 19 16 Gowers SG, Harrington RC, Whitton A, et al. Brief scale for measuring the outcomes 20 21 of emotional and behavioural disorders in children: Health of the Nation Outcome 22 Scales for Children and Adolescents (HoNOSCA). Br J Psychiatry 1999;174:413– 23 24 416. 25 26 17 Shaffer D, Gould MS, Brasic J, et al. A children's global assessment scale (CGAS). 27 Arch Gen Psychiatry 1983;40:1228–1231. 28 29 18 Office for National Statistics. Population Estimates for UK, England and Wales, 30 31 Scotland and Northern Ireland. Office for National Statistics, 2015. 32 33 19 Central Statistics Office for the Republic of Ireland. PEA11: Population estimates 34 from 1926 by Single Year of Age, Sex and Year, 35 36 https://www.cso.ie/px/pxeirestat/Statire/SelectVarVal/Define.asp?maintable=PEA11
37 http://bmjopen.bmj.com/ 38 &PLanguage=0. 39 40 20 Hakulinen T, Dyba T. Precision of incidence predictions based on Poisson distributed 41 observations. Stat Med 1994;13:1513–1523. 42 43 21 Gowers S, Levine W, Bailey-Rogers S, Shore A, Burhouse E. Use of a routine, self- 44
45 report outcome measure (HoNOSCA-SR) in two adolescent mental health services. on September 30, 2021 by guest. Protected copyright. 46 Br J Psychiatry 2002;180:266–269. 47 48 22 Gowers SG, Clark A, Roberts C, et al. Clinical effectiveness of treatments for 49 50 anorexia nervosa in adolescents: Randomised controlled trial. Br J Psychiatry 51 52 2007;191:427–435. 53 23 Favaro A, Caregaro L, Tenconi E, Bosello R, Santonastaso P. Time trends in age at 54 55 onset of anorexia nervosa and bulimia nervosa. J Clin Psychiatry 2009;70:1715–1721 56 57 24 Reas DL, Rø O. Time trends in healthcare‐detected incidence of anorexia nervosa and 58 bulimia nervosa in the Norwegian National Patient Register (2010–2016). Int J Eat 59 60 Disord 2018;51:1144–1152.
20 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 21 of 30 BMJ Open
1 2
3 25 NHS England. Access and Waiting Time Standard for Children and Young People BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 with an Eating Disorder: Commissioning Guide. London: National Collaborating 6 7 Centre for Mental Health, 2015. 8 9 10 11 12 13 14 15 16 17 18 For peer review only 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
37 http://bmjopen.bmj.com/ 38 39 40 41 42 43 44
45 on September 30, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
21 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 22 of 30
1 2
3 Table 1 Characteristics of incident cases BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 N Mean (SD) or % 6 7 Age 305 14.56 (1.66) 8 9 Sex 10 Female 279 91.48% 11 12 Male 26 8.52% 13 14 Ethnicity 15 Any White 274 91.64% 16 17 White and Asian 6 2.01% 18 For peer review only 19 White and Black Caribbean 2 0.67% 20 21 White and Black African 1 0.33% 22 Other Mixed 1 0.33% 23 24 Indian 3 1.00% 25 26 Pakistani 2 0.67% 27 28 Bangladeshi 1 0.33% 29 Other Asian 4 1.34% 30 31 Black Caribbean 2 0.67% 32 33 Chinese 1 0.33% 34 Ethnicity not known 2 0.67% 35 36 Clinical status 37 http://bmjopen.bmj.com/ 38 BMI 304 16.50 (2.25) 39 40 % of median expected BMI 303 83.23 (10.99) 41 CGAS 280 44.61 (14.08) 42 43 HoNOSCA 63 19.40 (8.17) 44
45 on September 30, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
22 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 23 of 30 BMJ Open
1 2
3 Table 2 Cases by region of the UK and Republic of Ireland BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 Incident Incident 6 Region Population N Population % * 7 cases N cases % 8 9 England 213 69.84% 6,194,444 77.83% 10 Scotland 44 14.43% 561,490 7.06% 11 12 Northern Ireland 41 13.44% 231,822 2.91% 13 14 Republic of Ireland 7 2.30% 628,251 7.89% 15 Wales 0 0.00% 342,627 4.31% 16 17 Total 305 7,958,634 18 For peer review only 19 * Does not sum to 100 due to rounding 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
37 http://bmjopen.bmj.com/ 38 39 40 41 42 43 44
45 on September 30, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
23 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 24 of 30
1 2
3 Table 3 Annual incidence of anorexia nervosa in young people aged 8 to 17 for 2015, BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 reported per 100,000 young people 6 7 Observed rate IR0 Adjusted rate IR1 Adjusted rate IR2 8 9 Age IR 95% CI IR 95% CI IR 95% CI 10 8 0.18 0.01 to 0.76 0.43 0.10 to 1.14 0.57 0.18 to 1.35 11 12 9 0.18 0.01 to 0.77 0.44 0.11 to 1.17 0.58 0.18 to 1.38 13 14 10 0.19 0.01 to 0.80 0.45 0.11 to 1.21 0.60 0.19 to 1.43 15 11 1.53 0.79 to 2.67 3.65 2.43 to 5.25 4.85 3.43 to 6.65 16 17 12 4.91 3.47 to 6.76 11.69 9.39 to 14.38 15.56 12.89 to 18.63 18 For peer review only 19 13 8.39 6.44 to 10.73 19.95 16.89 to 23.42 26.58 23.02 to 30.54 20 21 14 11.71 9.41 to 14.39 27.85 24.25 to 31.84 37.10 32.92 to 41.66 22 15 12.39 10.05 to 15.10 29.47 25.80 to 33.52 39.25 35.50 to 43.88 23 24 16 12.76 10.42 to 15.47 30.37 26.70 to 34.41 40.45 36.19 to 45.07 25 26 17 6.03 4.47 to 7.96 14.35 11.88 to 17.19 19.12 16.24 to 22.35 27 28 Total 5.75 5.23 to 6.30 13.68 12.88 to 14.52 18.22 17.29 to 19.18 29 30 31 32 33 34 35 36
37 http://bmjopen.bmj.com/ 38 39 40 41 42 43 44
45 on September 30, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
24 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
Page 25 of 30 BMJ Open
1 2 3 Table 4 Annual incidence of anorexia nervosa in young people aged 8 to 17 for 2015 by sex, reported per 100,000 young people 4 5 Observed incidence IR0 Adjusted incidence IR1 Adjusted incidence IR2 6 7 Age Female 95% CI Male 95% CI Female 95% CI Male 95% CI Female 95% CI Male 95% CI 8 8 0.36 0.02 to 1.55 0.00 0.00 to 0.00 0.87 0.21 to 2.34 0.00 0.00 to 0.00 1.16 0.36 to 2.76 0.00 0.00 to 0.00 9 10 9 0.00 0.00 to 0.00 0.35 0.02 to 1.52 0.00 0.00 to 0.00 0.85 0.21 to 2.28 0.00 0.00 to 0.00 1.13 0.35 to 2.69 11 10 0.39 0.02 to 1.65 0.00 0.00 to 0.00 0.93 0.23 to 2.48 0.00 0.00 to 0.00 1.23 0.39 to 2.93 0.00 0.00 to 0.00 12 For peer review only 13 11 2.35 1.07 to 4.46 0.75 0.15 to 2.18 5.59 3.47 to 8.51 1.77 0.71 to 3.63 7.44 4.96 to 10.72 2.37 1.11 to 4.42 14 12 8.05 5.43 to 11.50 1.92 0.80 to 3.86 19.17 14.98 to 24.16 4.56 2.69 to 7.22 25.53 20.66 to 31.21 6.09 3.89 to 9.08 15 16 13 16.36 12.48 to 21.06 0.78 0.16 to 2.28 38.93 32.81 to 45.86 1.85 0.75 to 3.79 51.83http://bmjopen.bmj.com/ 44.72 to 59.74 2.47 1.16 to 4.62 17 18 14 22.35 17.83 to 27.67 1.53 0.56 to 3.32 53.19 46.08 to 61.10 3.64 2.00 to 6.07 70.84 62.58 to 79.88 4.84 2.91 to 7.55 19 15 24.28 19.59 to 29.74 1.11 0.33 to 2.71 57.77 50.41 to 65.90 2.65 1.31 to 4.78 76.93 68.39 to 86.23 3.54 1.95 to 5.91 20 21 16 23.94 19.36 to 29.28 2.16 0.99 to 4.11 56.95 49.75 to 64.90 5.14 3.20 to 7.83 75.87 67.52 to 84.97 6.85 4.57 to 9.87 22 17 11.27 8.22 to 15.08 1.07 0.32 to 2.60 26.82 21.98 to 32.40 2.54 1.25 to 4.58 35.71 30.09 to 42.07 3.39 1.87 to 5.67 23 24 Total 10.78 9.77 to 11.87 0.96 0.68 to 1.30 25.66 24.09 to 27.30 2.28 1.84 to 2.79 34.17 on September 30, 2021 by guest. Protected copyright. 32.36 to 36.06 3.03 2.52 to 3.62 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 25 43 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 BMJ Open Page 26 of 30
1 2
3 Figure legends BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 6 Figure 1 Flow diagram of case ascertainment 7 8 9 10 11 12 13 14 15 16 17 18 For peer review only 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
37 http://bmjopen.bmj.com/ 38 39 40 41 42 43 44
45 on September 30, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
26 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 27 of 30 BMJ Open
1 2
3 Web extras BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 Case notification definition 6 7 Please report any child/young person aged 8 to 17 years and 11 months inclusive, who meets 8 the case notification definition criteria below for the first time in the last month. One bullet 9 10 point criterion from each group below should be fulfilled. 11 12 Group A 13 14 Restriction of food, low body weight, or 15 16 Weight less than expected for age 17 Group B 18 For peer review only 19 Fear of gaining weight, or 20 21 Fear of becoming fat, or 22 23 Behaviour that interferes with weight gain, for example excessive exercising, self- 24 induced vomiting, use of laxatives and diuretics 25 26 Group C 27 28 Body image disturbance, or 29 30 Persistent lack of recognition of the seriousness of the current low body weight 31 Exclusions 32 33 Patients who are not underweight 34 35 Patients with bulimia nervosa, binge eating disorder, avoidant restrictive food intake 36
37 disorder or other failure to thrive presentations http://bmjopen.bmj.com/ 38 39 40 41 42 43 44
45 on September 30, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
27 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 28 of 30
1 2
3 BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 Case notifications 5 n=997 6 7 8 9 Withdrew or excluded prior 10 to baseline data collection 11 n=48 12 13 14 15 No baseline data received 16 n=352 17 18 For peer review only 19 20 21 Baseline questionnaire 22 received 23 n=597 24 25 26 27 Ineligible for study 28 inclusion 29 n=285 30 31 32 33 Duplicate 34 n=7 35 36
37 http://bmjopen.bmj.com/ 38 39 Confirmed cases 40 41 n=305 42 43 44
45 on September 30, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 29 of 30 BMJ Open
1 2 STROBE Statement—Checklist of items that should be included in reports of cross-sectional studies
3 BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 Item Page 5 No Recommendation No 6 Title and abstract 1 (a) Indicate the study’s design with a commonly used 1 7 term in the title or the abstract 8 (b) Provide in the abstract an informative and balanced 2 9 10 summary of what was done and what was found 11 Introduction 12 Background/rationale 2 Explain the scientific background and rationale for the 5 13 14 investigation being reported 15 Objectives 3 State specific objectives, including any prespecified 5 16 hypotheses 17 18 Methods For peer review only 19 Study design 4 Present key elements of study design early in the paper 5-6 20 Setting 5 Describe the setting, locations, and relevant dates, 5 (setting, location), 6 21 including periods of recruitment, exposure, follow-up, (dates), 7-8 (data) 22 23 and data collection 24 Participants 6 (a) Give the eligibility criteria, and the sources and 6 (eligibility), 8 25 methods of selection of participants (selection) 26 27 Variables 7 Clearly define all outcomes, exposures, predictors, 7-8 (outcomes), 8 28 potential confounders, and effect modifiers. Give (diagnostic criteria) 29 diagnostic criteria, if applicable 30 Data sources/ 8* For each variable of interest, give sources of data and 7-8 31 32 measurement details of methods of assessment (measurement). 33 Describe comparability of assessment methods if there 34 is more than one group 35 Bias 9 Describe any efforts to address potential sources of bias 10, 14 36
37 Study size 10 Explain how the study size was arrived at n/a – population level http://bmjopen.bmj.com/ 38 Quantitative variables 11 Explain how quantitative variables were handled in the 9-11 39 analyses. If applicable, describe which groupings were 40 chosen and why 41 42 Statistical methods 12 (a) Describe all statistical methods, including those used 11 43 to control for confounding 44 (b) Describe any methods used to examine subgroups n/a 45 on September 30, 2021 by guest. Protected copyright. 46 and interactions 47 (c) Explain how missing data were addressed 9-11 48 (d) If applicable, describe analytical methods taking n/a 49 account of sampling strategy 50 51 (e) Describe any sensitivity analyses n/a 52 Results 53 Participants 13* (a) Report numbers of individuals at each stage of 11, Figure 1 54 55 study—eg numbers potentially eligible, examined for 56 eligibility, confirmed eligible, included in the study, 57 completing follow-up, and analysed 58 59 (b) Give reasons for non-participation at each stage 11, Figure 1 60 (c) Consider use of a flow diagram Figure 1
1 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 30 of 30
1 2 Descriptive data 14* (a) Give characteristics of study participants (eg 12, 22 (Table 1)
3 BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from demographic, clinical, social) and information on 4 5 exposures and potential confounders 6 (b) Indicate number of participants with missing data 22 (Table 1) 7 for each variable of interest 8 Outcome data 15* Report numbers of outcome events or summary n/a 9 10 measures 11 Main results 16 (a) Give unadjusted estimates and, if applicable, 12-13, 24-25 (Tables 3 12 confounder-adjusted estimates and their precision (eg, & 4) 13 95% confidence interval). Make clear which 14 15 confounders were adjusted for and why they were 16 included 17 (b) Report category boundaries when continuous n/a 18 For peer review only 19 variables were categorized 20 (c) If relevant, consider translating estimates of relative n/a 21 risk into absolute risk for a meaningful time period 22 Other analyses 17 Report other analyses done—eg analyses of subgroups n/a 23 24 and interactions, and sensitivity analyses 25 Discussion 26 Key results 18 Summarise key results with reference to study 13 27 28 objectives 29 Limitations 19 Discuss limitations of the study, taking into account 14-15 30 sources of potential bias or imprecision. Discuss both 31 direction and magnitude of any potential bias 32 33 Interpretation 20 Give a cautious overall interpretation of results 15 (interpretation), 13- 34 considering objectives, limitations, multiplicity of 14 (comparison with 35 analyses, results from similar studies, and other relevant similar studies) 36 evidence 37 http://bmjopen.bmj.com/ 38 Generalisability 21 Discuss the generalisability (external validity) of the 14 39 study results 40 41 Other information 42 Funding 22 Give the source of funding and the role of the funders 17 43 for the present study and, if applicable, for the original 44 study on which the present article is based 45 on September 30, 2021 by guest. Protected copyright. 46 47 *Give information separately for exposed and unexposed groups. 48 49 Note: An Explanation and Elaboration article discusses each checklist item and gives methodological background and 50 51 published examples of transparent reporting. The STROBE checklist is best used in conjunction with this article (freely 52 available on the Web sites of PLoS Medicine at http://www.plosmedicine.org/, Annals of Internal Medicine at 53 http://www.annals.org/, and Epidemiology at http://www.epidem.com/). Information on the STROBE Initiative is 54 available at www.strobe-statement.org. 55 56 57 58 59 60
2 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
Incidence of anorexia nervosa in young people in the United Kingdom and the Republic of Ireland: A national surveillance study ForJournal: peerBMJ Open review only Manuscript ID bmjopen-2018-027339.R2
Article Type: Research
Date Submitted by the 18-Jul-2019 Author:
Complete List of Authors: Petkova, Hristina; Institute of Psychiatry Psychology and Neuroscience, Health Service and Population Research Department Simic, Mima; South London and Maudsley NHS Foundation Trust Nicholls, Dasha; Imperial College London Ford, Tamsin; University of Exeter Prina, A.Matthew; Institute of Psychiatry Psychology and Neuroscience Stuart, Ruth; Institute of Psychiatry Psychology and Neuroscience, Health Service and Population Research Department Livingstone, Nuala; Queen's University Belfast Kelly, Grace; Queen's University Belfast Macdonald, Geraldine; University of Bristol Eisler, Ivan; South London and Maudsley NHS Foundation Trust
Gowers, Simon; University of Liverpool http://bmjopen.bmj.com/ Barrett, Barbara; Institute of Psychiatry Psychology and Neuroscience Byford, Sarah; Institute of Psychiatry Psychology and Neuroscience
Primary Subject Mental health Heading:
Secondary Subject Heading: Epidemiology
Eating disorders < PSYCHIATRY, Child & adolescent psychiatry < Keywords: on September 30, 2021 by guest. Protected copyright. PSYCHIATRY, EPIDEMIOLOGY, anorexia nervosa
For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 1 of 29 BMJ Open
1 2
3 Incidence of anorexia nervosa in young people in the United Kingdom and the Republic BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 of Ireland: A national surveillance study 6 7 Hristina Petkova, Institute of Psychiatry, Psychology & Neuroscience at King’s College 8 London (Research Fellow). 9 10 Mima Simic, South London and Maudsley NHS Foundation Trust (Consultant Child and 11 12 Adolescent Psychiatrist). 13 14 Dasha Nicholls, Imperial College London (Reader in Child and Adolescent Psychiatry). 15 Tamsin Ford, University of Exeter Medical School (Professor of Child and Adolescent 16 17 Psychiatry). 18 For peer review only 19 A. Matthew Prina, Institute of Psychiatry, Psychology & Neuroscience at King’s College 20 21 London (Senior Lecturer in Epidemiology). 22 Ruth Stuart, Institute of Psychiatry, Psychology & Neuroscience at King’s College London 23 24 (Research Assistant). 25 26 Nuala Livingstone, Queen’s University Belfast (Research Fellow). 27 Grace Kelly, Queen’s University Belfast (Research Fellow). 28 29 Geraldine Macdonald, University of Bristol (Professor of Social Work). 30 31 Ivan Eisler, South London and Maudsley NHS Foundation Trust (Professor of Family 32 33 Psychology and Family Therapy). 34 Simon Gowers, University of Liverpool (Professor of Adolescent Psychiatry). 35 36 Barbara Barrett, Institute of Psychiatry, Psychology & Neuroscience at King’s College
37 http://bmjopen.bmj.com/ 38 London (Senior Lecturer in Health Economics). 39 40 Sarah Byford, Institute of Psychiatry, Psychology & Neuroscience at King’s College London 41 (Professor of Health Economics). 42 43 44
45 Corresponding author: Sarah Byford, Institute of Psychiatry, Psychology & Neuroscience at on September 30, 2021 by guest. Protected copyright. 46 King’s College London, P024 David Goldberg Centre, De Crespigny Park, London SE5 8AF, 47 48 UK, [email protected], 02078480043 49 50 51 52 53 54 55 56 57 58 59 60
1 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 2 of 29
1 2
3 Abstract BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 Objectives: This study aimed to estimate the incidence of DSM5 anorexia nervosa in young 6 7 people in contact with child and adolescent mental health services in the UK and Republic of 8 Ireland. 9 10 Design: Observational, surveillance study using the Child and Adolescent Psychiatry 11 12 Surveillance System, involving monthly reporting by child and adolescent psychiatrists 13 st th 14 between 1 February 2015 and 30 September 2015. 15 Setting: UK and Republic of Ireland 16 17 Participants: Clinician-reported data on young people aged 8 to 17 in contact with child and 18 For peer review only 19 adolescent mental health services for a first episode of anorexia nervosa. 20 21 Main outcome measures: Annual incidence rates estimated as confirmed new cases per 22 100,000 population at risk. 23 24 Results: 305 incident cases of anorexia nervosa were reported over the 8-month surveillance 25 26 period and assessed as eligible for inclusion. The majority were young women (91%), from 27 England (70%), and of white ethnicity (92%). Mean age was 14.6 years (±1.66) and mean 28 29 percentage of median expected BMI for age and sex was 83.23% (±10.99%). The overall 30 31 incidence rate, adjusted for missing data, was estimated to be 13.68 per 100,000 population 32 33 (95% CI 12.88 to 14.52), with rates of 25.66 for young women (95% CI 24.09 to 27.30) and 34 2.28 for young men (95% CI 1.84 to 2.79). Incidence increased steadily with age, peaking at 35 36 15 for young women (57.77, 95% CI 50.41 to 65.90) and 16 for young men (5.14, 95% CI 3.20
37 http://bmjopen.bmj.com/ 38 to 7.83). Comparison with earlier estimates suggests incidence rates for children aged 13 and 39 40 under have increased over the last ten years. 41 Conclusions: These results provide new estimates of the incidence of anorexia nervosa in 42 43 young people. Service providers and commissioners should consider evidence to suggest an 44
45 increase in incidence in younger children. on September 30, 2021 by guest. Protected copyright. 46 Study registration: International Standard Randomised Controlled Trial Number Register 47 48 [ISRCTN12676087]. 49 50 51 52 Strengths and limitations of this study 53 The study benefits from a large, nationally representative sample from across the UK 54 55 and the Republic of Ireland. 56 57 58 59 60
2 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 3 of 29 BMJ Open
1 2
3 This study used a National surveillance system to collect data and thus avoided biases BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 inherent in studying clinical samples via a small number of centres in a limited 6 7 number of geographical areas. 8 9 Results were limited by missing data which was dealt with by adjusting observed 10 incidence rates using assumptions about incidence among missing cases. 11 12 Results are relevant to young people diagnosed with anorexia nervosa by child and 13 14 adolescent psychiatrists and not to those who are managed by general practitioners in 15 16 primary care or those who have not come to the attention of services, for example 17 those who choose not to seek help. 18 For peer review only 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
37 http://bmjopen.bmj.com/ 38 39 40 41 42 43 44
45 on September 30, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
3 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 4 of 29
1 2
3 Introduction BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 Anorexia nervosa is a serious and enduring eating disorder with high morbidity and the 6 1 7 highest mortality among psychiatric disorders. Young women are particularly susceptible, 8 with annual UK estimates of 37 new diagnoses of anorexia nervosa per 100,000 for girls aged 9 10 10 to 19 years, compared to 3 per 100,000 for boys of the same age.2 Prevalence estimates in 11 12 young people range from 0.3% to 0.6%.3–4 13 14 15 Accurate epidemiological estimates of the number of new anorexia nervosa cases per year 16 17 and their sex and age profile are needed for causal investigations and service planning.2 18 For peer review only 2,5–7 19 However, available estimates in the UK are at least ten years old. In addition, most 20 2,5 21 estimates are derived from community-based primary care records, which fail to accurately 22 record all new cases.8,9 Undetected anorexia nervosa cases may present to accident and 23 24 emergency and require immediate paediatric or psychiatric input, including inpatient 25 26 admission. Some young people may therefore bypass primary care and, consistent with UK 27 guidelines,10 are likely to be assessed and diagnosed by a child and adolescent psychiatrist in 28 29 a secondary care setting, making secondary care records a more reliable source of data on 30 31 anorexia nervosa incidence than primary care registers. 32 33 34 Existing incidence data from secondary care settings in the UK are limited. One study, 35 36 focusing only on adolescents aged 13 to 18, was limited to Greater London and reported
37 http://bmjopen.bmj.com/ 38 presentation rates to child and adolescent mental health services (CAMHS), rather than 39 6 40 incidence estimates. A second study, which used a national surveillance design, focused only 41 on children under 13.7 The current study aimed to estimate the incidence of anorexia nervosa 42 43 in secondary care services for young people between the ages of 8 and 17 years in the UK 44
45 and the Republic of Ireland. This work formed part of a study exploring the cost- on September 30, 2021 by guest. Protected copyright. 46 effectiveness of models of care for young people with eating disorders (the CostED study).11 47 48 49 50 Methods 51 52 Design 53 An observational, surveillance study was undertaken using the Child and Adolescent 54 55 Psychiatry Surveillance System (CAPSS). CAPSS is a system designed to ascertain cases of 56 57 rare childhood mental health conditions in the UK and Republic of Ireland through monthly 58 reporting by clinicians and relies on non-consent to maximise the accuracy of 59 60
4 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 5 of 29 BMJ Open
1 2
3 epidemiological estimates. The CAPSS system has been operating since 200912 and is based BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 on the well-established British Paediatric Surveillance Unit (BPSU) system.13 6 7 8 The study was approved by the CAPSS Executive Committee, King’s College London 9 10 Research Ethics Committee [PNM/13/14-105], and the Health Research Authority [CAG 4- 11 12 03(PR1)/2014] under Section 251 of the NHS Act 2006, which enables disclosure of 13 14 confidential patient information for purposes where it is not possible to use anonymised 15 information and where seeking consent is not practical. 16 17 18 For peer review only 19 Inclusion and exclusion criteria 20 21 The study included young people between 8 and 17 years of age, in contact with CAMHS for 22 a first episode of anorexia nervosa according to DSM5 diagnostic criteria.14 Anorexia 23 24 nervosa is exceptionally rare in children under 8 and the cut-off at 17 was due to the focus on 25 26 young people in contact with CAMHS, with many young people transitioning to adult 27 services at the age of 18. New cases were notified for a period of eight months from 1st 28 29 February to 30th September 2015. Cases whose clinician-reported data were insufficient to 30 31 assess eligibility were excluded, as were duplicate cases notified more than once by the same 32 33 or different clinicians. 34 35 36 Procedures
37 http://bmjopen.bmj.com/ 38 At the time of the study, CAPSS used a report card, known as the yellow card, containing a 39 40 list of conditions being surveyed. Yellow cards, along with reporting instructions and 41 protocols for new studies, are sent monthly from the CAPSS office to a mailing list of all 42 43 hospital, university and community child and adolescent consultant psychiatrists across the 44
45 United Kingdom and the Republic of Ireland. Reporting clinicians are asked to check boxes on September 30, 2021 by guest. Protected copyright. 46 against any of the reportable conditions they have seen in the preceding month, or to check a 47 48 "nil return" box and return the card to CAPSS. A tear-off slip is provided for respondents to 49 50 keep a record of the patients reported. "Positive" returns are allocated a unique CAPSS ID 51 52 number and notified to the appropriate research investigator, who then contacts the reporting 53 clinician directly to request completion of a questionnaire using the CAPSS ID to enable the 54 55 clinician to identify the relevant patient. 56 57 58 For the CostED study, the yellow card contained a check box for anorexia nervosa and was 59 60 sent to clinicians along with a protocol card detailing the case notification definition for
5 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 6 of 29
1 2
3 anorexia nervosa. The case notification definition (see web extras) was based on DSM5 BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 diagnostic criteria for anorexia nervosa and was intended to aid clinicians in their decision to 6 7 tick “yes” or “no” on the yellow card. It was not intended to identify whether a case met 8 study inclusion criteria, which was determined by the research group after receipt of all 9 10 necessary data. 11 12 13 14 Data 15 Questionnaires were sent to clinicians who reported a positive case of anorexia nervosa, 16 17 identified via the unique CAPSS ID number. Questionnaires were completed from clinical 18 For peer review only 19 records and clinicians were asked to provide data relating to the time the case was initially 20 21 assessed and diagnosed. The questionnaire covered clinical features to enable assessment of 22 case eligibility, referral pathway information to ensure assessment and diagnosis had not 23 24 happened prior to the study surveillance period, and a limited set of standard patient 25 26 identifiers in line with CAPSS procedures and ethics requirements, which were used to 27 describe the sample and to identify duplicate notifications. In addition, clinicians were asked 28 29 to confirm whether the case was a first episode of anorexia nervosa that had come to the 30 31 attention of services. 32 33 34 The patient identifiers included NHS or Community Health Index (CHI) number (unique 35 36 patient identifiers used in the regions of interest), hospital number, first half of postcode or
37 http://bmjopen.bmj.com/ 38 town of residence for the Republic of Ireland, sex, date of birth and ethnicity (White, Mixed, 39 40 Asian, Black, Chinese, Other or Unknown). In Northern Ireland, identifiers were limited to 41 age in years and months and hospital identifier rather than hospital number, to reduce the risk 42 43 of patient identification given the small geographic area. All patient identifiable data from 44
45 Northern Ireland were retained by the local research team, de-duplicated, anonymised and on September 30, 2021 by guest. Protected copyright. 46 subsequently sent to the central research team in King’s College London for analysis as per 47 48 requirements set out by the Northern Ireland Privacy Advisory Committee. All data storage 49 50 was compliant with the EU General Data Protection Regulations. 51 52 53 Clinical features included: weight and height to calculate body mass index (BMI) and 54 55 percentage of median expected BMI for age and sex interpreted around the 85% threshold;15 56 16 57 the Health of the Nation Outcome Scales for Children and Adolescents (HoNOSCA ), a 58 routine outcome measure rating 13 clinical features on a five-point severity scale including 59 60 behaviours, impairments, symptoms, and social functioning of children and adolescents with
6 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 7 of 29 BMJ Open
1 2
3 mental health problems; the clinician completed Children's Global Assessment Scale BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 (CGAS17) used to rate emotional and behavioural functioning of young people; and a range of 6 7 symptoms relating to the diagnosis of anorexia nervosa. 8 9 10 Unreturned or incomplete questionnaires were chased via email and telephone. Cases where 11 12 any symptom required for case definition was absent despite chasing, were assessed for 13 14 eligibility by a consultant child and adolescent psychiatrist (MS). 15 16 17 Case eligibility 18 For peer review only 19 Cases were assessed as eligible for the study if: (a) they were between 8 and 17 years of age; 20 21 (b) they had no previous episode of anorexia nervosa that had come to the attention of 22 services; (c) they received a clinical assessment in the reporting service during the study 23 24 surveillance period; (d) they had not been referred from another secondary health service (to 25 26 ensure assessment and diagnosis had not happened prior to study surveillance period); and (e) 27 the following clinical symptoms were present: “Restriction of energy intake relative to 28 29 requirements” and “Persistent behaviour that interferes with weight gain, despite low 30 31 weight”. This broad definition was subsequently checked using a tighter DSM5 analytic 32 33 definition including the following symptoms: 34 1) “Restriction of energy intake relative to requirements” and 35 36 2) “Intense fear of gaining weight or of becoming fat” or “Persistent behaviour that
37 http://bmjopen.bmj.com/ 38 interferes with weight gain, despite low weight” and 39 40 3) “Perception that body shape/size is larger than it is” or “Preoccupation with body 41 weight and shape” or “Lack of recognition of the seriousness of the current low body 42 43 weight” 44
45 Only one case which met the broad criteria failed to meet the tighter criteria, thus confirming on September 30, 2021 by guest. Protected copyright. 46 the validity of the broad criteria. 47 48 49 50 Removal of duplicates 51 52 Duplicates were identified by comparing NHS/CHI numbers, hospital numbers/ hospital 53 identifiers and date of birth/age in years and months, as appropriate. The management of 54 55 duplicates depended upon the outcome for the original notification for which a duplicate was 56 57 identified. Four scenarios were considered: (1) duplicates where the original notification met 58 study inclusion criteria were excluded and the original retained; (2) duplicates where the 59 60 original notification had been excluded because the young person was under 8 years of age or
7 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 8 of 29
1 2
3 did not meet the clinical criteria were assessed as a new case to determine if the case now met BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 eligibility criteria; (3) duplicates where the original notification was excluded due to a 6 7 previous episode of anorexia nervosa, a diagnosis date prior to the study surveillance period 8 or referral from another secondary care service, were excluded; and (4) duplicates where the 9 10 original notification contained insufficient information to judge eligibility were checked to 11 12 see if the duplicate contained the missing information and, if available, the original 13 14 notification was reassessed for eligibility and the duplicate managed as per the scenarios 15 above. 16 17 18 For peer review only 19 Data analysis 20 21 Data analysis was performed using Stata IC v14.2 and Microsoft Excel 2010. Observed 22 incidence rates (denoted IR0), defined as the number of new cases during a specified period 23 24 of time in a population at risk for developing the disease, were calculated as follows: the 25 26 number of confirmed new cases of anorexia nervosa in the 8-month surveillance period 27 converted to 12 months [(N cases over 8 months/8)*12], divided by the population at risk and 28 29 multiplied by 100,000 to give the rate per 100,000 young people. 30 31 32 33 IR0 = (confirmed new cases converted to 12 months)/the population at risk *100,000 34 35 36 The population at risk was calculated as the total number of children of each year of age and
37 http://bmjopen.bmj.com/ 38 each sex in the UK and Republic of Ireland minus the number of prevalent cases who, once 39 40 diagnosed, are no longer part of the “at risk” population. Population data for 2015 were 41 obtained from the Office for National Statistics for the UK18 and the Central Statistics Office 42 43 for the Republic of Ireland.19 To estimate the number of prevalent cases each year, incident 44
45 cases in the previous age band were used as a proxy. For example, incident cases aged eight on September 30, 2021 by guest. Protected copyright. 46 were used as a proxy for prevalent cases in the estimation of the ‘at risk’ population aged 47 48 nine, and so on. 49 50 51 52 To consider incidence among unobserved missing cases, adjustments were needed for 53 unreturned CAPSS notification cards and questionnaires. For CAPSS notification cards, just 54 55 over half of all notification cards sent out were returned (50.16%). To account for incidence 56 57 among the 49.84% of unreturned cards, two assumptions were made, and an appropriate 58 correction applied to IR0, the observed incidence rate: 59 60
8 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 9 of 29 BMJ Open
1 2
3 Assumption 1: To take into consideration the possibility that unreturned cards are more likely BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 to be ‘nil’ returns, it was assumed that half of unreturned cards (24.92%) were ‘negative’ and 6 7 half followed the same proportion of ‘negative’ and ‘positive’ as the returned cards. This 8 assumption translates into a correction coefficient of 1.50 derived from (24.92+50.16)/50.16. 9 10 11 12 Assumption 2: Making no assumptions of bias in the likelihood of unreturned cards being 13 14 either positive or negative returns, it was assumed that all unreturned cards followed the same 15 proportion of ‘negative’ and ‘positive’ as returned cards. This assumption translates into a 16 17 correction coefficient of 1.99 derived from (49.84+50.16)/50.16. 18 For peer review only 19 20 21 These assumptions provide a range of incidence rates, from a minimum (observed incidence 22 rate) to a maximum (assumption 2), within which the actual rate is likely to fall. We 23 24 hypothesised that assumption 1 provides the most realistic estimate since it assumes a bias in 25 26 the response rates with greater likelihood that unreturned cards are negative (‘nil’ returns) but 27 does not assume all unreturned cards are ‘nil’ returns, which is the implicit assumption within 28 29 IR0. 30 31 32 33 For unreturned questionnaires, approximately two-thirds of the questionnaires that were sent 34 to clinicians reporting positive cases of anorexia nervosa were returned (63%), leaving one- 35 36 third (37%) unreturned. Since all these questionnaires relate to a ‘positive’ notification, we
37 http://bmjopen.bmj.com/ 38 applied a correction coefficient of 1.59 derived from (37+63)/63, which assumes that the 39 40 incidence rate for the unreturned questionnaires is the same as the incidence rate identified in 41 the returned questionnaires for each year of age. 42 43 44
45 We then combined the correction coefficients described above, to generate two adjusted on September 30, 2021 by guest. Protected copyright. 46 incidence rates: 47 48 49 50 Adjusted incidence rate 1 (IR1) = Confirmed new cases of anorexia nervosa converted to 12 51 52 months, multiplied by the correction for unreturned CAPSS notification cards under 53 assumption 1, multiplied by the correction for unreturned questionnaires, then divided by the 54 55 population at risk and multiplied by 100,000. 56 57 58 IR1 = (confirmed new cases converted to 12 months * 1.50 * 1.59)/the population at risk 59 60 *100,000
9 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 10 of 29
1 2
3 BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 Adjusted Incidence rate 2 (IR2) = Confirmed new cases of anorexia nervosa converted to 12- 6 7 months, multiplied by the correction for unreturned CAPSS notification cards under 8 assumption 2, multiplied by the correction for unreturned questionnaires and then divided by 9 10 the population at risk and multiplied by 100,000. 11 12 13 14 IR2 = (confirmed new cases converted to 12 months * 1.99 * 1.59)/the population at risk * 15 100,000 16 17 18 For peer review only 19 For each incidence rate, IR0, IR1 and IR2, total, age-specific and sex-specific annual 20 21 incidence rates for anorexia nervosa for the year 2015 and 95% confidence intervals were 22 calculated based on the Poisson distribution20 using the Stata command ci means [N new 23 24 anorexia nervosa cases 12m], Poisson [exposure(total population)] for positive 25 26 integers/whole incidence numbers (Stata interprets any non-integer decimal point number 27 between 0 and 1 as the fraction of events and converts it to an integer number). Annual 28 29 incidence rates were stratified by discrete age and sex. 30 31 32 33 Public and patient involvement statement 34 The CostED study included a patient and a parent representative on the study steering 35 36 committee who contributed to the design, conduct and management of the study, including
37 http://bmjopen.bmj.com/ 38 the incidence component. 39 40 41 Results 42 43 Case ascertainment 44
45 Case ascertainment is outlined in Figure 1. Over the eight-month surveillance period, 6401 on September 30, 2021 by guest. Protected copyright. 46 yellow cards were sent to reporting clinicians and 3211 were returned (50%). Of these, 997 47 48 positive cases of anorexia nervosa were reported and 2214 were nil returns. Of the positive 49 50 cases, 48 (5%) were excluded due to clinicans stating that they did not wish to be included in 51 52 the study (due to retirement, shortage of reporting capacity etc.) or due to reporting errors. 53 Questionnaires were sent to the remaining 949, and a further 352 positive cases (37%) were 54 55 excluded as they failed to return the questionnaires, so no data were available to assess 56 57 eligibility. Questionnaires were completed and returned for 597 notified cases, of which 292 58 (49%) were ineligible for reasons related to age, previous episode of anorexia nervosa, date 59 60 of assessment outside the study’s surveillance period, referral from another secondary care
10 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 11 of 29 BMJ Open
1 2
3 service, insufficient information to assess diagnosis or duplicate notifications, leaving 305 BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 incident cases of anorexia nervosa as the sample for analysis. 6 7 8 Demographics and clinical features 9 10 Of the 305 young people identified as having DSM5 anorexia nervosa, the majority were 11 12 girls (91%), from England (70%) and of white ethnicity (92%) (see Table 1). The mean age 13 14 was 14.6 years (±1.66). Clinical variables suggest these young people were significantly 15 impaired. Mean BMI was 16.50 kg/m2 (±2.25), where values of 16.00 to 16.99 suggesting 16 17 moderate severity of anorexia nervosa. Mean percentage of median expected BMI for age and 18 For peer review only 19 sex (the deviation from expected body weight) was 83.23% (±10.99%), falling within the 20 21 range required for a diagnosis of anorexia nervosa (<85%). Mean CGAS score was 44.61 22 (±14.08), which falls within the range for ‘obvious problems’ (41–50) on a scale from 1 to 23 24 100 (1 being the worst and 100 the best emotional and behavioural functioning). Mean total 25 26 HoNOSCA score was 19.40 (±8.17) on a scale from 0 to 52, indicative of a severity similar to 27 that at inpatient admission.21,22 28 29 30 31 The proportion of the included sample notified from each region within the British Isles is 32 33 reported in Table 2, alongside the population of young people in each region by age. England 34 has the largest population (78%) and notified 70% of new cases. Scotland, containing only 35 36 7% of the total population, notified 14% of the sample and Northern Ireland, containing only
37 http://bmjopen.bmj.com/ 38 3% of the population, notified 13% of the sample. By contrast, the Republic of Ireland 39 40 notified only 2% of cases, despite containing 8% of the population, and Wales notified no 41 eligible cases (some cases were notified but did not meet inclusion criteria), despite 42 43 containing 4% of the population. 44
45 on September 30, 2021 by guest. Protected copyright. 46 Incidence rates 47 48 Table 3 details observed incidence rates (IR0) and adjusted incidence rates (IR1 and IR2) by 49 50 age. Incidence rates for the total sample ranged from a minimum of 5.75 per 100,000 young 51 52 people (95% CI 5.23 to 6.30; IR0) to a maximum of 18.22 per 100,000 young people (95% 53 CI 17.29 to 19.18; IR2), with IR1, the rate hypothesised to be the most accurate, falling 54 55 between these two values at 13.68 per 100,000 population (95% CI 12.88 to 14.52). Focusing 56 57 on IR1 rates, total incidence increased steadily with age, peaking at 16 (30.37, 95% CI 26.70 58 to 34.41), with a substantial drop at the age of 17 (14.35, 95% CI 11.88 to 17.19). 59 60
11 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 12 of 29
1 2
3 Table 4 reports incidence rates by age and sex. Incidence among young men followed a BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 similar pattern to overall incidence rates reported in Table 3, being highest at the age of 16 6 7 (5.14) and half that at age 17 (2.54). The highest incidence among young women was seen a 8 year earlier than for boys, at the age of 15 (57.77), with similar rates at age 16 (56.95), 9 10 dropping by more than half at age 17 (26.82). 11 12 13 14 Discussion 15 Principal findings 16 17 This study provides new estimates of incident cases of anorexia nervosa in young people 18 For peer review only 19 aged 8 to 17 presenting to CAMHS services in the UK and Republic of Ireland. Our mid- 20 21 range, missing data-adjusted estimate (IR1) of the incidence of anorexia nervosa in the full 22 sample of young people aged 8 to 17 years was approximately 14 per 100,000. 23 24 25 26 Comparison with other studies 27 This result is lower than previous primary care-based estimates of 18–20 per 100,000 28 29 focusing on young people aged 10–19.2,5 This difference is due to the different age ranges in 30 31 the studies; the inclusion of children as young as 8 in the current study, who have relatively 32 33 low incidence, and exclusion of adolescents aged 18 to 19, whose incidence is relatively high, 34 makes the results difficult to compare. However, comparing rates for 10 to 14-year olds, 35 36 available in both studies, produces similar incidence rates, with rates of 12.6 per 100,000 in
37 http://bmjopen.bmj.com/ 38 the current study, compared to 13.1 per 100,000 in 2009.2 For females, the rates are 23.3 per 39 40 100,000 in the current study compared to 24.0 per 100,000 in 2009 and for males, 2.4 and 2.5 41 per 100,000, respectively. However, this comparison should be treated with caution given the 42 43 very different settings – primary care versus secondary care. 44
45 on September 30, 2021 by guest. Protected copyright. 46 Existing secondary care estimates of the incidence of anorexia nervosa in the UK are limited 47 48 to children under the age of 13, with an overall incidence of 1.09 per 100,000 reported for 49 50 children aged between 6 and 13 between 2005 and 2006.7 The methodology for this study was 51 52 very similar to the CostED methodology, using the CAPSS system but additionally the British 53 Paediatric Surveillance System. For comparison with the current study, the incidence rate for 54 55 children between 8 and 13 was approximately 1.5 per 100,000 for DSMIV anorexia nervosa or 56 57 1.8 per 100,000 for DSMIV anorexia nervosa plus ‘other eating disorders’ likely to contain 58 cases that would now be classified as anorexia nervosa using DSM5. This compares to a rate 59 60 of 5.83 per 100,000 in the current study for children of the same age. This estimate is
12 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 13 of 29 BMJ Open
1 2
3 substantially higher than the 2006 estimates suggesting that incidence rates for younger BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 children have increased over time. 6 7 8 The results presented are also supported by international evidence. One study carried out in 9 10 Italy demonstrated a significant reduction in age at onset for anorexia nervosa in consecutive 11 12 outpatient referrals between 1985 and 2008 (n=1,666).23 A second study exploring time trends 13 14 in the incidence of anorexia nervosa, which was carried out using data from the Norwegian 15 National Patient Register, found overall rates of anorexia nervosa to be stable between 2010 16 17 and 2016 for the sample as a whole, but increasing for young females aged between 10 and 18 For peer review only 19 14.24 20 21 22 Strengths and weaknesses of the study 23 24 The large, nationally representative sample of this study is a strength. The study included 25 26 young people with anorexia nervosa, diagnosed using DSM5 criteria, from across the UK and 27 the Republic of Ireland and thus avoided biases inherent in studying clinical samples via a 28 29 small number of centres in a limited number of geographical areas. The results are of 30 31 relevance primarily to the UK and Republic of Ireland but may be of value to other high- 32 33 income countries. 34 35 36 With only a 50% response rate from CAPSS clinicians and a third of questionnaires not
37 http://bmjopen.bmj.com/ 38 returned, missing data were a major constraint. There are many reasons why clinicians may 39 40 fail to return notification cards or questionnaires, including changes in place of employment, 41 competing priorities, or the belief that cases will be reported by a colleague.13 This problem 42 43 was addressed by adjusting the observed incidence rates using assumptions about incidence 44
45 among both missing case notifications and missing questionnaires. on September 30, 2021 by guest. Protected copyright. 46 47 48 The methodology is also limited to young people seen by child and adolescent psychiatrists. 49 50 Cases that would not be identified by this methodology include those who have not come to 51 52 the attention of services, for example those who choose not to seek help, those managed by 53 general practitioners in primary care, and those in the care of mental health services without 54 55 psychiatric input, such as nurse-led facilities. This latter concern was an issue in Northern 56 57 Ireland where, due to initial low numbers of notifications, investigation by the research team 58 identified a number of nurse-led facilities which were invited to contribute, and subsequently 59 60 reported just over half of all cases in Northern Ireland. In terms of missing primary care
13 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 14 of 29
1 2
3 cases, given UK guidelines for assessment and diagnosis of anorexia nervosa to be carried BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 out by child and adolescent psychiatrists in secondary care settings,10 it is reasonable to 6 7 assume that many of those cases remaining in primary care would not meet criteria for DSM5 8 anorexia nervosa. It is also possible that current inpatient cases are under-represented; 9 10 although notifications were sent to all child and adolescent psychiatrists, including those 11 12 working in inpatient settings, the main focus of the CostED study was the evaluation of 13 14 community-based services, and so clinicians may have mistakenly focused on notification of 15 community-based cases. 16 17 18 For peer review only 19 It must also be borne in mind that service-level (rather than population-level) incidence rates 20 21 are sensitive to external factors, including service availability, funding and commissioning 22 decisions, parental and school awareness, stigma, etc., all of which will impact upon observed 23 24 trends in incidence rates over time. The nature of community-based eating disorders services 25 26 for children and adolescents in England has started to change following the publication of 27 commissioning standards in June 2015,25 as well as investment of £30 million to support the 28 29 development of these services. The CostED incidence data were collected in 2015, one year 30 31 before the first allocation of funding to services was made in 2016, and thus these initiatives, 32 33 which may result in increases in observed incidence rates in the future, are not reflected in the 34 data presented. Nevertheless, these estimates are approximately ten years more recent than 35 36 existing secondary care data for the UK (collected between 2005 and 2006)7 and cover a
37 http://bmjopen.bmj.com/ 38 wider age range. 39 40 41 Unanswered questions and future research 42 43 Future research should explore the development of earlier interventions, given evidence of an 44
45 increase in incidence in young children suggesting that onset of anorexia nervosa may be on September 30, 2021 by guest. Protected copyright. 46 starting earlier for some young people than suggested by previous research. Research is also 47 48 needed to identify approaches to the assessment of incidence simultaneously in primary and 49 50 secondary care. Multinational studies should be considered for better assessment and 51 52 exploration of incidence rates in young men. 53 54 55 Conclusion 56 57 These results provide new estimates of the incidence of anorexia nervosa in young people in 58 the UK and Republic of Ireland. Whilst firm conclusions relating to changes in incidence 59 60 rates over time for the entire sample cannot be drawn due to lack of existing secondary care
14 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 15 of 29 BMJ Open
1 2
3 evidence, service providers and commissioners should consider evidence to suggest an BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 increase in incidence in younger children. 6 7 8 Word count 9 10 4111 11 12 13 14 Acknowledgements 15 We would like to thank all the clinicians who were kind enough to give up their time to 16 17 provide the CostED study with CAPSS notifications and to complete questionnaires. We 18 For peer review only 19 know your time is precious and in short supply and we are truly grateful. We would also like 20 21 to thank the team at the Child and Adolescent Psychiatry Surveillance System, based at the 22 Royal College of Psychiatrist’s Centre for Care Quality and Improvement, for their support 23 24 with the design and running of the surveillance aspect of this study, and the study steering 25 26 committee for their invaluable advice. 27 28 29 Contributor and guarantor information 30 31 Hristina Petkova contributed to data collection, data entry, data cleaning, data analysis, and 32 33 drafting of the manuscript. 34 Mima Simic was a co-applicant, contributed to the design of the study, provided clinical 35 36 expertise, and commented on and approved the manuscript.
37 http://bmjopen.bmj.com/ 38 Dasha Nicholls was a co-applicant, contributed to the design of the study, provided expertise 39 40 on CAPSS methodology, clinical expertise, and commented on and approved the manuscript. 41 Tamsin Ford was a co-applicant, contributed to the design of the study, provided clinical 42 43 expertise, and commented on and approved the manuscript. 44
45 Matthew Prina contributed to the data analysis and commented on and approved the on September 30, 2021 by guest. Protected copyright. 46 manuscript. 47 48 Ruth Stuart contributed to data collection, data entry, data cleaning and data analysis, and 49 50 commented on and approved the manuscript. 51 52 Nuala Livingstone contributed to data collection, data entry and data management in 53 Northern Ireland, and commented on and approved the manuscript. 54 55 Grace Kelly contributed to data collection, data entry and data management in Northern 56 57 Ireland, and commented on and approved the manuscript. 58 Geraldine Macdonald contributed to the design of the study, managed the Northern Ireland 59 60 research staff, and commented on and approved the final report.
15 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 16 of 29
1 2
3 Ivan Eisler was a co-applicant, contributed to the design of the study, provided clinical BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 support to the research team, and commented on and approved the manuscript. 6 7 Simon Gowers was a co-applicant, contributed to the design of the study, provided clinical 8 expertise, and commented on and approved the manuscript. 9 10 Barbara Barrett was a co-applicant, contributed to the design of the study, the data analysis, 11 12 and commented on and approved the manuscript. 13 14 Sarah Byford was principal investigator, led the study, managed the King’s College London 15 research staff, contributed to the design of the study and the data analysis, drafted the paper, 16 17 and is responsible for the overall content as guarantor. 18 For peer review only 19 20 21 Competing interests 22 Tamsin Ford reports she is Chair of the Child and Adolescent Psychiatry Surveillance Service 23 24 that was used to run part of the study, which is an unpaid position (other than travel 25 26 expenses). Kandarp Joshi reports that he was principal investigator for the Aberdeen site for a 27 Sunovion sponsored multisite trial on effectiveness of Lurasidone in paediatric schizophrenia. 28 29 No other authors report conflicts of interest. 30 31 32 33 Transparency statement 34 The lead author affirms that this manuscript is an honest, accurate, and transparent account of 35 36 the study being reported; that no important aspects of the study have been omitted; and that
37 http://bmjopen.bmj.com/ 38 any discrepancies from the study as planned and registered have been explained. 39 40 41 Role of the funding source 42 43 The study was funded by the NIHR Health Service & Delivery Research programme 44
45 (11/1023/17). The study funders had no role in the study design, the collection, analysis or on September 30, 2021 by guest. Protected copyright. 46 interpretation of data, the writing of the report, or the decision to submit the article for 47 48 publication. The authors were independent from the funders and all authors had full access to 49 50 all of the data in the study and can take responsibility for the integrity of the data and the 51 52 accuracy of the data analysis. 53 54 55 Disclaimer 56 57 The views expressed are those of the authors and not necessarily those of the NHS, the NIHR 58 or the Department of Health and Social Care. 59 60
16 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 17 of 29 BMJ Open
1 2
3 Data sharing BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 As a result of the collection of confidential patient data without consent, and approval from 6 7 the Health Research Authority (following advice from the Confidentiality Advisory Group) 8 for data to be provided for the purposes of the specified activity only, the data cannot be 9 10 made publicly available for other purposes. However, the CostED research group will 11 12 consider requests for further analysis on a case by case basis, subject to appropriate 13 14 ethical/HRA approvals. All data enquiries should be submitted to the corresponding author 15 for consideration in the first instance. 16 17 18 For peer review only 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
37 http://bmjopen.bmj.com/ 38 39 40 41 42 43 44
45 on September 30, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
17 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 18 of 29
1 2
3 References BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 1 Arcelus J, Mitchell AJ, Wales J, Nielsen S. Mortality rates in patients with anorexia 6 7 nervosa and other eating disorders: A meta-analysis of 36 Studies. Arch Gen 8 Psychiatry 2011;68:724–731. 9 10 2 Micali N, Hagberg KW, Petersen I, Treasure JL. The incidence of eating disorders in 11 12 the UK in 2000-2009: findings from the General Practice Research Database. BMJ 13 14 Open 2013;3:e002646. 15 3 Hoek HW. Incidence, prevalence and mortality of anorexia nervosa and other eating 16 17 disorders. Curr Opin Psychiatry 2006;19:389–394. 18 For peer review only 19 4 Smink FRE, van Hoeken D, Hoek HW. Epidemiology of eating disorders: incidence, 20 21 prevalence and mortality rates. Current Psychiatry Reports 2012;14:406–414. 22 5 Currin L, Schmidt U, Treasure J, Jick H. Time trends in eating disorder incidence. Br 23 24 J Psychiatry 2005;186:132–135. 25 26 6 House J, Schmidt U, Craig M, et al. Comparison of specialist and nonspecialist care 27 pathways for adolescents with anorexia nervosa and related eating disorders. Int J Eat 28 29 Disord 2012;45:949–956. 30 31 7 Nicholls DE, Lynn R, Viner RM. Childhood eating disorders: British national 32 33 surveillance study. Br J Psychiatry 2011;98:295–301. 34 8 Lask B, Bryant‐Waugh R, Wright F, Campbell M, Willoughby K, Waller G. Family 35 36 physician consultation patterns indicate high risk for early-onset anorexia nervosa. Int
37 http://bmjopen.bmj.com/ 38 J Eat Disord 2005;38:269–272. 39 40 9 Goodman R, Ford T, Simmons H, Gatward R, Meltzer H. Using the Strengths and 41 Difficulties Questionnaire (SDQ) to screen for child psychiatric disorders in a 42 43 community sample. Br J Psychiatry 2000;177:534–539. 44
45 10 National Institute for Health and Care Excellence. Eating disorders: recognition and on September 30, 2021 by guest. Protected copyright. 46 treatment. NICE guideline [NG69]. National Institute for Health and Care Excellence, 47 48 2017. 49 50 11 Byford S, Petkova H, Stuart R, et al. Alternative community-based models of care for 51 52 young people with anorexia nervosa: the CostED national surveillance study. Health 53 Service and Delivery Research 2019 (in press). 54 55 12 Lynn RM, Viner RM, Nicholls DE. Ascertainment of early onset eating disorders: a 56 57 pilot for developing a national child psychiatric surveillance system. Child Adolesc 58 59 Ment Health 2012;17:109–112. 60
18 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 19 of 29 BMJ Open
1 2
3 13 Knowles RL, Friend H, Lynn R, Mitchell S, Michie C, Ihekweazu C. Surveillance of BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 rare diseases: a public health evaluation of the British Paediatric Surveillance Unit. J 6 7 Public Health 2012;34:279–286. 8 14 American Psychiatric Association. Diagnostic and Statistical Manual of Mental 9 10 Disorders (DSM–5), Fifth Edition. Washington DC: American Psychiatric 11 12 Association, 2013. 13 14 15 Le Grange D, Doyle PM, Swanson SA, Ludwig K, Glunz K, Kreipe RE. Calculation 15 of expected body weight in adolescents with eating disorders. Pediatrics 16 17 2012;129:e438–e446. 18 For peer review only 19 16 Gowers SG, Harrington RC, Whitton A, et al. Brief scale for measuring the outcomes 20 21 of emotional and behavioural disorders in children: Health of the Nation Outcome 22 Scales for Children and Adolescents (HoNOSCA). Br J Psychiatry 1999;174:413– 23 24 416. 25 26 17 Shaffer D, Gould MS, Brasic J, et al. A children's global assessment scale (CGAS). 27 Arch Gen Psychiatry 1983;40:1228–1231. 28 29 18 Office for National Statistics. Population Estimates for UK, England and Wales, 30 31 Scotland and Northern Ireland. Office for National Statistics, 2015. 32 33 19 Central Statistics Office for the Republic of Ireland. PEA11: Population estimates 34 from 1926 by Single Year of Age, Sex and Year, 35 36 https://www.cso.ie/px/pxeirestat/Statire/SelectVarVal/Define.asp?maintable=PEA11
37 http://bmjopen.bmj.com/ 38 &PLanguage=0. 39 40 20 Hakulinen T, Dyba T. Precision of incidence predictions based on Poisson distributed 41 observations. Stat Med 1994;13:1513–1523. 42 43 21 Gowers S, Levine W, Bailey-Rogers S, Shore A, Burhouse E. Use of a routine, self- 44
45 report outcome measure (HoNOSCA-SR) in two adolescent mental health services. on September 30, 2021 by guest. Protected copyright. 46 Br J Psychiatry 2002;180:266–269. 47 48 22 Gowers SG, Clark A, Roberts C, et al. Clinical effectiveness of treatments for 49 50 anorexia nervosa in adolescents: Randomised controlled trial. Br J Psychiatry 51 52 2007;191:427–435. 53 23 Favaro A, Caregaro L, Tenconi E, Bosello R, Santonastaso P. Time trends in age at 54 55 onset of anorexia nervosa and bulimia nervosa. J Clin Psychiatry 2009;70:1715–1721 56 57 24 Reas DL, Rø O. Time trends in healthcare‐detected incidence of anorexia nervosa and 58 bulimia nervosa in the Norwegian National Patient Register (2010–2016). Int J Eat 59 60 Disord 2018;51:1144–1152.
19 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 20 of 29
1 2
3 25 NHS England. Access and Waiting Time Standard for Children and Young People BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 with an Eating Disorder: Commissioning Guide. London: National Collaborating 6 7 Centre for Mental Health, 2015. 8 9 10 11 12 13 14 15 16 17 18 For peer review only 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
37 http://bmjopen.bmj.com/ 38 39 40 41 42 43 44
45 on September 30, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
20 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 21 of 29 BMJ Open
1 2
3 Table 1 Characteristics of incident cases BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 N Mean (SD) or % 6 7 Age 305 14.56 (1.66) 8 9 Sex 10 Female 279 91.48% 11 12 Male 26 8.52% 13 14 Ethnicity 15 Any White 274 91.64% 16 17 White and Asian 6 2.01% 18 For peer review only 19 White and Black Caribbean 2 0.67% 20 21 White and Black African 1 0.33% 22 Other Mixed 1 0.33% 23 24 Indian 3 1.00% 25 26 Pakistani 2 0.67% 27 28 Bangladeshi 1 0.33% 29 Other Asian 4 1.34% 30 31 Black Caribbean 2 0.67% 32 33 Chinese 1 0.33% 34 Ethnicity not known 2 0.67% 35 36 Clinical status 37 http://bmjopen.bmj.com/ 38 BMI 304 16.50 (2.25) 39 40 % of median expected BMI 303 83.23 (10.99) 41 CGAS 280 44.61 (14.08) 42 43 HoNOSCA 63 19.40 (8.17) 44
45 on September 30, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
21 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 22 of 29
1 2
3 Table 2 Cases by region of the UK and Republic of Ireland BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 Incident Incident 6 Region Population N Population % * 7 cases N cases % 8 9 England 213 69.84% 6,194,444 77.83% 10 Scotland 44 14.43% 561,490 7.06% 11 12 Northern Ireland 41 13.44% 231,822 2.91% 13 14 Republic of Ireland 7 2.30% 628,251 7.89% 15 Wales 0 0.00% 342,627 4.31% 16 17 Total 305 7,958,634 18 For peer review only 19 * Does not sum to 100 due to rounding 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
37 http://bmjopen.bmj.com/ 38 39 40 41 42 43 44
45 on September 30, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
22 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 23 of 29 BMJ Open
1 2
3 Table 3 Annual incidence of anorexia nervosa in young people aged 8 to 17 for 2015, BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 reported per 100,000 young people 6 7 Observed rate IR0 Adjusted rate IR1 Adjusted rate IR2 8 9 Age IR 95% CI IR 95% CI IR 95% CI 10 8 0.18 0.01 to 0.76 0.43 0.10 to 1.14 0.57 0.18 to 1.35 11 12 9 0.18 0.01 to 0.77 0.44 0.11 to 1.17 0.58 0.18 to 1.38 13 14 10 0.19 0.01 to 0.80 0.45 0.11 to 1.21 0.60 0.19 to 1.43 15 11 1.53 0.79 to 2.67 3.65 2.43 to 5.25 4.85 3.43 to 6.65 16 17 12 4.91 3.47 to 6.76 11.69 9.39 to 14.38 15.56 12.89 to 18.63 18 For peer review only 19 13 8.39 6.44 to 10.73 19.95 16.89 to 23.42 26.58 23.02 to 30.54 20 21 14 11.71 9.41 to 14.39 27.85 24.25 to 31.84 37.10 32.92 to 41.66 22 15 12.39 10.05 to 15.10 29.47 25.80 to 33.52 39.25 35.50 to 43.88 23 24 16 12.76 10.42 to 15.47 30.37 26.70 to 34.41 40.45 36.19 to 45.07 25 26 17 6.03 4.47 to 7.96 14.35 11.88 to 17.19 19.12 16.24 to 22.35 27 28 Total 5.75 5.23 to 6.30 13.68 12.88 to 14.52 18.22 17.29 to 19.18 29 30 31 32 33 34 35 36
37 http://bmjopen.bmj.com/ 38 39 40 41 42 43 44
45 on September 30, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
23 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from
BMJ Open Page 24 of 29
1 2 3 Table 4 Annual incidence of anorexia nervosa in young people aged 8 to 17 for 2015 by sex, reported per 100,000 young people 4 5 Observed incidence IR0 Adjusted incidence IR1 Adjusted incidence IR2 6 7 Age Female 95% CI Male 95% CI Female 95% CI Male 95% CI Female 95% CI Male 95% CI 8 8 0.36 0.02 to 1.55 0.00 0.00 to 0.00 0.87 0.21 to 2.34 0.00 0.00 to 0.00 1.16 0.36 to 2.76 0.00 0.00 to 0.00 9 10 9 0.00 0.00 to 0.00 0.35 0.02 to 1.52 0.00 0.00 to 0.00 0.85 0.21 to 2.28 0.00 0.00 to 0.00 1.13 0.35 to 2.69 11 10 0.39 0.02 to 1.65 0.00 0.00 to 0.00 0.93 0.23 to 2.48 0.00 0.00 to 0.00 1.23 0.39 to 2.93 0.00 0.00 to 0.00 12 For peer review only 13 11 2.35 1.07 to 4.46 0.75 0.15 to 2.18 5.59 3.47 to 8.51 1.77 0.71 to 3.63 7.44 4.96 to 10.72 2.37 1.11 to 4.42 14 12 8.05 5.43 to 11.50 1.92 0.80 to 3.86 19.17 14.98 to 24.16 4.56 2.69 to 7.22 25.53 20.66 to 31.21 6.09 3.89 to 9.08 15 16 13 16.36 12.48 to 21.06 0.78 0.16 to 2.28 38.93 32.81 to 45.86 1.85 0.75 to 3.79 51.83http://bmjopen.bmj.com/ 44.72 to 59.74 2.47 1.16 to 4.62 17 18 14 22.35 17.83 to 27.67 1.53 0.56 to 3.32 53.19 46.08 to 61.10 3.64 2.00 to 6.07 70.84 62.58 to 79.88 4.84 2.91 to 7.55 19 15 24.28 19.59 to 29.74 1.11 0.33 to 2.71 57.77 50.41 to 65.90 2.65 1.31 to 4.78 76.93 68.39 to 86.23 3.54 1.95 to 5.91 20 21 16 23.94 19.36 to 29.28 2.16 0.99 to 4.11 56.95 49.75 to 64.90 5.14 3.20 to 7.83 75.87 67.52 to 84.97 6.85 4.57 to 9.87 22 17 11.27 8.22 to 15.08 1.07 0.32 to 2.60 26.82 21.98 to 32.40 2.54 1.25 to 4.58 35.71 30.09 to 42.07 3.39 1.87 to 5.67 23 24 Total 10.78 9.77 to 11.87 0.96 0.68 to 1.30 25.66 24.09 to 27.30 2.28 1.84 to 2.79 34.17 on September 30, 2021 by guest. Protected copyright. 32.36 to 36.06 3.03 2.52 to 3.62 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 24 43 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Page 25 of 29 BMJ Open
1 2
3 Figure legends BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 6 Figure 1 Flow diagram of case ascertainment 7 8 9 10 11 12 13 14 15 16 17 18 For peer review only 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
37 http://bmjopen.bmj.com/ 38 39 40 41 42 43 44
45 on September 30, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
25 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 26 of 29
1 2
3 Web extras BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 5 Case notification definition 6 7 Please report any child/young person aged 8 to 17 years and 11 months inclusive, who meets 8 the case notification definition criteria below for the first time in the last month. One bullet 9 10 point criterion from each group below should be fulfilled. 11 12 Group A 13 14 Restriction of food, low body weight, or 15 16 Weight less than expected for age 17 Group B 18 For peer review only 19 Fear of gaining weight, or 20 21 Fear of becoming fat, or 22 23 Behaviour that interferes with weight gain, for example excessive exercising, self- 24 induced vomiting, use of laxatives and diuretics 25 26 Group C 27 28 Body image disturbance, or 29 30 Persistent lack of recognition of the seriousness of the current low body weight 31 Exclusions 32 33 Patients who are not underweight 34 35 Patients with bulimia nervosa, binge eating disorder, avoidant restrictive food intake 36
37 disorder or other failure to thrive presentations http://bmjopen.bmj.com/ 38 39 40 41 42 43 44
45 on September 30, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
26 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 27 of 29 BMJ Open
1 2
3 BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 Case notifications 5 n=997 6 7 8 9 Withdrew or excluded prior 10 to baseline data collection 11 n=48 12 13 14 15 No baseline data received 16 n=352 17 18 For peer review only 19 20 21 Baseline questionnaire 22 received 23 n=597 24 25 26 27 Ineligible for study 28 inclusion 29 n=285 30 31 32 33 Duplicate 34 n=7 35 36
37 http://bmjopen.bmj.com/ 38 39 Confirmed cases 40 41 n=305 42 43 44
45 on September 30, 2021 by guest. Protected copyright. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml BMJ Open Page 28 of 29
1 2 STROBE Statement—Checklist of items that should be included in reports of cross-sectional studies
3 BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from 4 Item Page 5 No Recommendation No 6 Title and abstract 1 (a) Indicate the study’s design with a commonly used 1 7 term in the title or the abstract 8 (b) Provide in the abstract an informative and balanced 2 9 10 summary of what was done and what was found 11 Introduction 12 Background/rationale 2 Explain the scientific background and rationale for the 5 13 14 investigation being reported 15 Objectives 3 State specific objectives, including any prespecified 5 16 hypotheses 17 18 Methods For peer review only 19 Study design 4 Present key elements of study design early in the paper 5-6 20 Setting 5 Describe the setting, locations, and relevant dates, 5 (setting, location), 6 21 including periods of recruitment, exposure, follow-up, (dates), 7-8 (data) 22 23 and data collection 24 Participants 6 (a) Give the eligibility criteria, and the sources and 6 (eligibility), 8 25 methods of selection of participants (selection) 26 27 Variables 7 Clearly define all outcomes, exposures, predictors, 7-8 (outcomes), 8 28 potential confounders, and effect modifiers. Give (diagnostic criteria) 29 diagnostic criteria, if applicable 30 Data sources/ 8* For each variable of interest, give sources of data and 7-8 31 32 measurement details of methods of assessment (measurement). 33 Describe comparability of assessment methods if there 34 is more than one group 35 Bias 9 Describe any efforts to address potential sources of bias 10, 14 36
37 Study size 10 Explain how the study size was arrived at n/a – population level http://bmjopen.bmj.com/ 38 Quantitative variables 11 Explain how quantitative variables were handled in the 9-11 39 analyses. If applicable, describe which groupings were 40 chosen and why 41 42 Statistical methods 12 (a) Describe all statistical methods, including those used 11 43 to control for confounding 44 (b) Describe any methods used to examine subgroups n/a 45 on September 30, 2021 by guest. Protected copyright. 46 and interactions 47 (c) Explain how missing data were addressed 9-11 48 (d) If applicable, describe analytical methods taking n/a 49 account of sampling strategy 50 51 (e) Describe any sensitivity analyses n/a 52 Results 53 Participants 13* (a) Report numbers of individuals at each stage of 11, Figure 1 54 55 study—eg numbers potentially eligible, examined for 56 eligibility, confirmed eligible, included in the study, 57 completing follow-up, and analysed 58 59 (b) Give reasons for non-participation at each stage 11, Figure 1 60 (c) Consider use of a flow diagram Figure 1
1 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml Page 29 of 29 BMJ Open
1 2 Descriptive data 14* (a) Give characteristics of study participants (eg 12, 22 (Table 1)
3 BMJ Open: first published as 10.1136/bmjopen-2018-027339 on 22 October 2019. Downloaded from demographic, clinical, social) and information on 4 5 exposures and potential confounders 6 (b) Indicate number of participants with missing data 22 (Table 1) 7 for each variable of interest 8 Outcome data 15* Report numbers of outcome events or summary n/a 9 10 measures 11 Main results 16 (a) Give unadjusted estimates and, if applicable, 12-13, 24-25 (Tables 3 12 confounder-adjusted estimates and their precision (eg, & 4) 13 95% confidence interval). Make clear which 14 15 confounders were adjusted for and why they were 16 included 17 (b) Report category boundaries when continuous n/a 18 For peer review only 19 variables were categorized 20 (c) If relevant, consider translating estimates of relative n/a 21 risk into absolute risk for a meaningful time period 22 Other analyses 17 Report other analyses done—eg analyses of subgroups n/a 23 24 and interactions, and sensitivity analyses 25 Discussion 26 Key results 18 Summarise key results with reference to study 13 27 28 objectives 29 Limitations 19 Discuss limitations of the study, taking into account 14-15 30 sources of potential bias or imprecision. Discuss both 31 direction and magnitude of any potential bias 32 33 Interpretation 20 Give a cautious overall interpretation of results 15 (interpretation), 13- 34 considering objectives, limitations, multiplicity of 14 (comparison with 35 analyses, results from similar studies, and other relevant similar studies) 36 evidence 37 http://bmjopen.bmj.com/ 38 Generalisability 21 Discuss the generalisability (external validity) of the 14 39 study results 40 41 Other information 42 Funding 22 Give the source of funding and the role of the funders 17 43 for the present study and, if applicable, for the original 44 study on which the present article is based 45 on September 30, 2021 by guest. Protected copyright. 46 47 *Give information separately for exposed and unexposed groups. 48 49 Note: An Explanation and Elaboration article discusses each checklist item and gives methodological background and 50 51 published examples of transparent reporting. The STROBE checklist is best used in conjunction with this article (freely 52 available on the Web sites of PLoS Medicine at http://www.plosmedicine.org/, Annals of Internal Medicine at 53 http://www.annals.org/, and Epidemiology at http://www.epidem.com/). Information on the STROBE Initiative is 54 available at www.strobe-statement.org. 55 56 57 58 59 60
2 For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml