Follow-Up Survey of Patients with Occupational Asthma

Occupational Medicine 2020;70:231–234 Advance Access publication on 20 April 2020 doi:10.1093/occmed/kqaa049

Follow-up survey of patients with occupational asthma

J. Feary1,2, J. Cannon1, B. Fitzgerald1, J. Szram1, S. Schofield2 and P. Cullinan1,2 1Department of Occupational Lung Disease, Royal Brompton and Harefield NHS Foundation Trust, London SW3 6NP, UK, 2National Heart and Lung Institute, Imperial College, London SW3 6LR, UK. Downloaded from https://academic.oup.com/occmed/article/70/4/231/5822611 by guest on 28 September 2021 Correspondence to: J. Feary, National Heart and Lung Institute, Imperial College, London SW3 6LR, UK. Tel: +44 020 7594 7968; e-mail: [email protected]

Background Occupational asthma (OA) is often associated with a poor prognosis and the impact of a diagnosis on an individual’s career and income can be significant. Aims We sought to understand the consequences of a diagnosis of OA to patients attending our clinic. Methods Using a postal questionnaire, we surveyed all patients attending our specialist occupational lung disease clinic 1 year after having received a diagnosis of OA due to a sensitizer (n = 125). We enquired about their current health and employment status and impact of their diagnosis on various aspects of their life. Additional information was collected by review of clinical records. Results We received responses from 71 (57%) patients; 77% were referred by an occupational health (OH) provider. The median duration of symptoms prior to referral was 18 months (interquartile range (IQR) 8–48). At 1 year, 79% respondents were no longer exposed to the causal agent. Whilst the unexposed patients reported an improvement in symptoms compared with those still exposed (82% versus 53%; P = 0.023), they had poorer outcomes in terms of career, income and how they felt treated by their employer; particularly those not currently employed. Almost all (>90%) of those still employed had been referred by an OH provider compared with 56% of those currently unemployed (P = 0.002). Conclusions The negative impact of OA on people’s careers, livelihood and quality of life should not be underestimated. However, with early detection and specialist care, the prognosis is often good and particularly so for those with access to occupational health. Key words Allergy; asthma; occupation; outcomes.

Introduction between May 2006 and May 2016 with a final diagnosis of OA (n = 125). Patients with suspected OA had a diag- Occupational asthma (OA) caused by exposure to work- nosis made (or excluded) using: a history of exposure place respiratory sensitizers is not uncommon. In the UK to a known respiratory sensitizer; the presence of work- an estimated 200–300 new cases of OA are reported an- related respiratory symptoms following a period of la- nually to a national surveillance scheme (‘SWORD’) but tency; measurement of appropriate specific antibodies or this is undoubtedly an underestimate of the true figure skin prick tests (if available); and, if the patient was still [1]. Most affected individuals are of working age and fi- exposed, analysis of serial peak flow recordings carried nancially dependent on their job. Patients with OA are out over a minimum of 4 weeks with at least four record- usually advised to avoid further exposure to the causative ings made each day and including both days at and away antigen which in many cases leads to a change of job, from work. Where it was not possible to make a defini- often with a loss of earnings. We sought to understand tive diagnosis on these tests alone, or in cases where a the consequences of a diagnosis of OA on our patient novel asthmagen was purported to be the causal agent, population. specific inhalation testing as an inpatient using a single- blind approach was carried out in line with European Methods consensus guidelines [2]. The final diagnosis was made by consensus following discussion at a multidisciplinary As part of routine care, we surveyed all patients at- meeting which includes physicians, specialist nurses and tending our specialist occupational lung disease service immunologists. For the purposes of this study we did not

Key learning points

What is already known about this subject: • Occupational asthma is often associated with a poor prognosis particularly if diagnosis is delayed and with ongoing exposure to the causative agent. • The impact of a diagnosis of occupational asthma on an individual, particularly with respect to their future employment and income, can be significant. What this study adds: • The prognosis of occupational asthma in our population is good overall, particularly in those removed from the causal agent with improvement in symptoms occurring within a few months. • Individuals referred by their occupational health service were more likely to remain in employment after diagnosis and to have a better prognosis. Downloaded from https://academic.oup.com/occmed/article/70/4/231/5822611 by guest on 28 September 2021 • Most participants reported that the diagnosis of occupational asthma had had a negative impact on their career, income and quality of life. What impact this may have on practice or policy: • Health care professionals should have a low threshold for suspecting occupational asthma in people with work- related symptoms to reduce the time to diagnosis and removal of exposure thereby improving prognosis. • Many patients feel unsupported by their employer following a diagnosis of occupational asthma and consider- ation should be given on how to improve this. • People diagnosed with occupational asthma should have access to occupational health to improve outcomes. include patients with a diagnosis of work-exacerbated most were male (69%); 77% were referred by an occupa- asthma or those with irritant-induced asthma. tional health (OH) provider (Table 1). We reviewed the clinical records of patients with OA The median duration of symptoms prior to referral to determine the duration of symptoms prior to referral, was 18 months (interquartile range (IQR) 8–48) and sig- exposure history and source of referral. One year after nificantly shorter for those who reported an improvement diagnosis we sent each patient a postal questionnaire. in symptoms at 1 year compared with those whose symp- The questionnaire enquired into their current employ- toms were unchanged or worse (17 months (IQR 6–36) ment and symptoms including if they were working versus 24 months (IQR 12–192); P = 0.016). Over 80% with the same employer or a different employer and if of participants reported an improvement in symptoms they were still working with the agent that caused their with a median time for this to occur of 3 months (IQR asthma and if so whether their exposure was unchanged 1–6); 16% reported complete resolution of symptoms. or reduced. Using a five-point Likert scale, the ques- Most patients (79%) were no longer exposed to the tionnaire also asked their opinion about how they were cause of their OA; they were more likely to report an im- treated by their employer after diagnosis, and the impact provement in symptoms than those still exposed (82% on their quality of life, career progression and income. versus 53%; P = 0.023). However, they reported poorer Finally, we asked about whether they had made a claim outcomes in terms of career, income and treatment by for Industrial Injuries Disablement Benefit (IIDB). their employer (Figure 1); this was particularly so for Responses to questions measured on the five-point those who were not currently employed (24%). Likert scale were ‘collapsed’ to binary variables for analysis. Using STATA version 14 (Stata Corp, College Station, 81 TX, USA), we assessed associations between categorical Symptoms improved (P =0.085) 82 variables using Pearson’s chi-squared test or Fisher’s exact 53 100 test; and analysed differences in means using t-tests, and Held back in career (P =0.004) 80 medians using the Mann–Whitney U-test. A P-value of 50 <0.05 was considered statistically significant. 94 Held back in income (P =0.001) 54 33

87 Results Treated less well by employer (P <0.001) 34 15

We received responses from 71 (57%) patients. There 0102030405060708090100 were no significant differences in age, sex or occupation Percentage between those who did and did not reply. The majority Removed from exposure (unemployed) (n =17) Removed from exposure (employed) (n =39) Exposed (n =15) of respondents were sensitized to high-molecular-weight Figure 1. Outcomes by removal from exposure (P-values correspond agents (bakery and laboratory animal allergens) and to the differences between the groups using a chi-squared test). J. FEARY ET AL.: FOLLOW-UP SURVEY OF PATIENTS WITH OA 233

Almost all the patients who were still employed (80% provided by nurses and doctors either ‘in-house’ or via an of those with, and 90% of those without ongoing ex- external contract. In our study patients referred directly posure) had been referred by an OH provider, a propor- from OH services were more likely to remain employed tion far higher than among those currently unemployed and report favourable outcomes. Possible explanations (53%; P = 0.008). A greater proportion of those referred for this observation include a reflection of better care from OH stated that their quality of life had improved from such specialists, or that employers who access OH or been unaffected following diagnosis compared to services are more likely to be accommodating of changes those referred from other sources (51% versus 20%; needed in those who develop OA. P = 0.043). The main strength of our study lies in its consistency Overall, fewer than half made a claim for IIDB; this of diagnosis and management advice, and our enquiry was particularly the case for animal workers and scien- into a range of different patient-focused outcomes. The

tists where only 13% made a claim compared with 53% generalizability of our findings may be limited by the Downloaded from https://academic.oup.com/occmed/article/70/4/231/5822611 by guest on 28 September 2021 of other workers (P = 0.004). Overall, most patients modest response rate. We report the outcomes of patients (86%) reported being ‘glad’ that their diagnosis had been referred to a specialist clinical centre; our findings may made and 99% (missing data for one respondent) were not be representative of all workers with OA and particu- satisfied with the service they had received from us. larly not those in whom the diagnosis is not made at all. We limited our study population to those with OA due Discussion to a respiratory sensitizer with latency. Irritant-induced asthma (or ‘reactive airways dysfunction syndrome’) and At 1 year after diagnosis, most of our patients with OA work-exacerbated asthma both have different underlying were no longer exposed to the aetiological agent. The mechanisms and correspondingly require different man- majority reported an improvement in symptoms with agement strategies. 16% being asymptomatic but that their diagnosis had The favourable prognosis that we observed probably had a negative impact on their career, income and quality reflects the relatively short period of symptomatic ex- of life. Nonetheless, a strong majority were glad that the posure before referral and diagnosis; the median dur- diagnosis had been made. In the UK, OH services are ation of symptoms at time of first consultation here was

Table 1. Agents causing occupational asthma in respondents and outcomes 12 months after diagnosis; by source of referral

All (n = 71), OH referrals Non-OH referralsa P-value n (%) (n = 56) (77%) (n = 15) (21%)

Exposure Allergen Bakery allergens 26 (37) 20 (36) 6 (40) 0.370 Laboratory animal allergens 16 (23) 15 (27) 1 (7) Isocyanates 7 (10) 4 (7) 3 (20) Detergent enzymes 6 (8) 5 (9) 1 (7) Platinum salts 3 (4) 3 (5) 0 (0) Solder fumes (colophony) 3 (4) 2 (4) 1 (7) Metal working fluids 2 (3) 2 (4) 0 (0) Other allergensb 8 (11) 5 (9) 3 (20) Outcomes Change in symptoms Same/worse 17 (24) 14 (26) 3 (20) 1.000 Improved 53 (76) 41 (75) 12 (80) Career Held back 53 (78) 41 (76) 12 (86) 0.719 Unaffected/improved 15 (22) 13 (24) 2 (14) Income Held back 41 (59) 29 (53) 12 (80) 0.078 Unaffected/improved 29 (41) 65 (47) 3 (20) Quality of life Decreased 39 (56) 27 (49) 12 (80) 0.042 Unaffected/unsure 31 (44) 28 (51) 3 (20) Treated well by employer 38 (58) 33 (62) 5 (39) 0.120 Claimed IIDB 30 (43) 24 (44) 6 (40) 1.000 ‘Glad’ diagnosis made 58 (86) 45 (87) 13 (87) 1.000 Current employment Employed 54 (76) 47 (84) 7 (47) 0.003 status Unemployed 17 (24) 9 (16) 8 (53) a10 referred from hospital doctors (eight of whom were respiratory specialists) and five from general practitioners (GPs). bn = 1 case each of OA due to methacrylates, stainless steel fumes, obeche wood, sodium persulphate, jellyfish, herbicide, nematodes, pharmaceuticals. 234 OCCUPATIONAL MEDICINE just 18 months, much lower than the mean of 4 years re- detection and care in a specialist centre, the prognosis ported elsewhere [3]. A meta-analysis of 39 studies found is often good. a pooled estimate of complete symptomatic recovery of 32% after avoidance of exposure to the causative agent Competing interests [4] but with a longer follow-up time than our population (median 31 months (range 6–240)) suggesting our None declared. patients may continue to improve over time. National asthma guidelines state that the possibility of OA should References be considered at an early stage and patients referred for specialist investigation to allow prompt identification of 1. Health and Safety Executive. Work Related Asthma in Great potential cases [5]. A recent study from Canada reported Britain, 2018. http://www.hse.gov.uk/statistics/causdis/

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