Aortic Dissection in Pregnancy in England: an Incidence Study Using Linked National Databases
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Open Access Research BMJ Open: first published as 10.1136/bmjopen-2015-008318 on 20 August 2015. Downloaded from Aortic dissection in pregnancy in England: an incidence study using linked national databases Amitava Banerjee,1 Irena Begaj,2 Sara Thorne3 To cite: Banerjee A, Begaj I, ABSTRACT Strengths and limitations of this study Thorne S. Aortic dissection in Objectives: To conduct the first population-level pregnancy in England: an incidence study of aortic dissection in pregnancy using ▪ incidence study using linked This is the first analysis to consider aortic dis- linked hospital-based data in England. national databases. BMJ section in pregnancy across England using data Open 2015;5:e008318. Setting: Hospital-based data (Hospital Episode from multiple sources. doi:10.1136/bmjopen-2015- Statistics (HES) linked with mortality data from the Office ▪ These are the first data regarding the incidence 008318 of National Statistics), national enquiries (Confidential of all aortic dissections (not just deaths) in Enquiries into Maternal Mortality) and surveys (UK England for the time period 2003–2011. ▸ Prepublication history for Obstetric Surveillance System; UKOSS) of aortic ▪ There is considerable variation in the character- this paper is available online. dissection in pregnancy from 2003 to 2011 in England. istics of different databases of maternal mortality To view these files please Participants: Between 2003 and 2011, all female and morbidity, and their findings. visit the journal online patients admitted with diagnoses of aortic dissection (not ▪ This study shows that a combination of data (http://dx.doi.org/10.1136/ necessarily as the primary cause of admission) and of sources is probably necessary in order to make bmjopen-2015-008318). pregnancy, childbirth and puerperium, were included. optimal estimates of incidence and outcome of Outcome measures: Diagnosis of aortic dissection aortic dissection in pregnancy, and although rou- Received 26 March 2015 tinely collected clinical data may have important Revised 14 July 2015 during pregnancy, operated or not operated, with Accepted 24 July 2015 outcome of death or live patient from 2003 to 2011 in uses, there are still significant concerns such as England. the quality of data linkage. Results: There were significant differences in characteristics of databases with respect to study 3 population, time of study, recorded event and follow-up largest registry of aortic dissection. of outcomes. On the basis of HES, annual incidence of Importantly, most individuals with aortic dis- aortic dissection was 1.23 (95% CI 1.22 to 1.24) per 100 section had inadequately controlled hyper- http://bmjopen.bmj.com/ 000 maternities. Incidence of aortic dissection with death tension, suggesting that modifiable risk within 1 year was 0.30 (0.29 to 0.31) per 100 000 factors may play a role in prevention.2 maternities. Incidence of aortic dissection increased from Moreover, women have worse outcomes fol- – 0.74 (0.73 to 0.75) per 100 000 maternities in 2003 lowing surgery for aortic dissection,3 and the 2005 to 1.52 (1.51 to 1.53) per 100 000 maternities in surgical risk is even higher during preg- 2009–2011. In the Confidential Enquiries into Maternal nancy.45The majority of aortic dissections in Deaths, incidence of deaths was highest for 2003–2005 – women of childbearing age occur during (0.43/100 000 maternities) and lowest for 1997 1999 on September 30, 2021 by guest. Protected copyright. (0.21/100 000 maternities). In the UK Obstetric pregnancy and have adverse consequences 6 Surveillance System, national incidence of aortic for the mother and the fetus. Data from the dissection was 0.80 (0.50 to 1.50) per 100 000 Swedish National Birth Registry in women maternities between 2009 and 2011. <40 years of age have shown that pregnancy Conclusions: The case of aortic dissection in pregnancy is associated with a 25-fold increased risk of illustrates data limitations regarding complications in aortic dissection.6 The scientific literature pregnancy from different sources in the UK, even for a regarding aortic dissection and pregnancy is 1University of Birmingham diagnosis with seemingly few alternative coding and largely made up of case reports and case Centre for Cardiovascular diagnostic possibilities. These limitations should be series, mostly in individuals with connective Sciences, Birmingham, UK acknowledged when estimating incidence and outcome. tissue diseases, from the last 70 years.78A lit- 2Quality Outcomes Research Unit, Queen Elizabeth erature review of outcomes in pregnant Hospital, Birmingham, UK INTRODUCTION women with acute aortic dissection from 3Department of Cardiology, Aortic dissection, though rare, is an often 2003 to 2013 included 59 articles and only Queen Elizabeth Hospital, fatal event.1 A recent population-based study 75 patients.9 Two population-based studies Birmingham, UK from Oxford showed that women have have considered pregnancy and aortic dissec- 10 11 Correspondence to higher mortality from aortic dissection and tion in the European context, suggesting Dr Amitava Banerjee; are more likely to die before hospital assess- high mortality from aortic dissection in [email protected] ment,2 which was also shown by the world’s pregnancy. Banerjee A, et al. BMJ Open 2015;5:e008318. doi:10.1136/bmjopen-2015-008318 1 Open Access BMJ Open: first published as 10.1136/bmjopen-2015-008318 on 20 August 2015. Downloaded from In the UK, the Confidential Enquiry into Maternal International Statistical Classification of Diseases 10th Deaths (CEMD) has historically provided data regarding revision (ICD-10:I710, I711, I712), not necessarily as the aortic dissection and other causes of maternal mortal- primary cause of admission, and with a diagnosis of ity,12 and has shown an increase in deaths from cardio- pregnancy, childbirth and puerperium (ICD-10: vascular disease during pregnancy in recent years. O00-O99, Z33), were included in the analysis using Although the CEMD (which became the Confidential ICD-10 codes.20 In addition, data for aortic dissection Enquiries into Maternal and Child Health, CEMACH, in operations were extracted using OPCS4 codes:21 2003,12 and is now known as MBRRACE, Mother and L18-L21, L273, L274, L283, L284, L221, K26, K66, K33. Babies: Reducing Risk through Audits and Confidential The same data regarding aortic dissection from CEMD/ Enquiries13) provides crucial mortality data and com- CEMACH22 and UKOSS23 were extracted for the time pares favourably with surveillance systems in other coun- period between 2003 and 2011 from published reports. – tries,12 14 it is not designed to detect morbidity or The number of aortic dissection events, deaths in hos- burden of disease and there have been concerns regard- pital and at 1 year, and whether the aortic dissection was ing the completeness of its data.15 As a result, UKOSS surgically managed, were recorded, where possible. (UK Obstetric Surveillance System) has run prospective surveys into the outcomes of rare conditions in preg- Databases nancy, for example, pregnancy-related myocardial infarc- The Informatics Department of the University Hospitals tion (MI).16 17 The CEMACH 2006–2008 report Birmingham NHS Trust24 has access to Hospital Episode highlighted 53 cardiac deaths, of which 7 (13.2%) were Statistics (HES)25 for all inpatient admissions in due to aortic dissection, translating to 0.31 deaths due England, and Office of National Statistics (ONS) mortal- to aortic dissection per 100 000 maternities. ity statistics.26 Data linkage between the two data sets is Studies of MI have highlighted potentially large dis- carried out by the Health and Social Care Information crepancies between primary and secondary care data- Centre (HSCIC). Data from CEMD/CEMACH22/ bases and disease registries when estimating incidence, UKOSS21 were extracted from published reports. and therefore surveys are unlikely to be accurate for less commonly researched conditions such as aortic dissec- Outcomes tion.18 The use of routinely collected clinical data for A maternal death is defined by the WHO as ‘‘the death public health benefit is an important topic of recent of a woman while pregnant or within 42 days of termin- debate, involving both population-level (‘big data’) and ation of pregnancy”.20 Mortality within 42 days of birth individual-level (‘small data’) considerations.19 Ideally, was used as the reported outcome despite considerable estimates of incidence should be made at multiple levels debate regarding the extension of this time period to in the healthcare system, or at least at the national level, reflect the effects of pregnancy and childbirth over a but this has not been previously attempted, to the best of longer timeframe,27 because it is the most widely http://bmjopen.bmj.com/ our knowledge, and no population-level study of hospital- reported. The time to surgery was defined as up to based data, to date, has considered aortic dissection in 60 days, in order to include both acute and subacute pregnancy in England or in the UK. We conducted the surgery as stipulated by previous studies.28 This time first detailed analysis of England’s national hospital-level period was also chosen to better reflect the operative data linked to mortality statistics in order to characterise burden of aortic dissection in pregnancy. incidence and outcome of aortic dissection in pregnancy and to compare with data from the Confidential Data analysis Enquiries into Maternal Mortality and UKOSS. Absolute numbers of aortic dissection cases for each on September 30, 2021 by guest. Protected copyright. year were compared for HES/ONS data versus CEMD/ CEMACH/UKOSS. The incidence rates per 100 000 AIMS maternities and per 100 000 conceptions were calculated The present study had two distinct aims: for HES/ONS and compared with estimates from ▸ To estimate national incidence of aortic dissection in UKOSS. A maternity is a pregnancy resulting in the women during pregnancy from hospital-based data birth of one or more children, including stillbirths and linked to mortality statistics.