Occupational asthma
BMJ 2016; 353 doi: https://doi.org/10.1136/bmj.i2658 (Published 03 June 2016) Cite this as: BMJ 2016;353:i2658
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We offer a different definition for occupational asthma to that of Feary et al. [1] A UK consensus definition for occupational asthma is 'asthma which is induced by exposure in the working environment to airborne dusts,vapours or fumes, in workers with or without pre-existing asthma'. [2]
Consequently occupational asthma can be subdivided into sensitiser-induced occupational asthma characterised by a latency period between first exposure to a respiratory sensitiser at work and the development of immunologically-mediated symptoms; and irritant-induced occupational asthma that occurs typically within a few hours of a high concentration exposure to an irritant gas, fume or vapour at work. [3] Almost 90% of cases of occupational asthma are of the sensitiser-induced type [3] discussed by Feary et al.
We agree that patients who present in general practice should be asked about a temporal relationship between their symptoms and attending work. It is also important to establish biological plausibility and to ask any adult patient with new, recurrent or deteriorating symptoms of rhinitis or asthma about their job and the materials with which they work. [4]
Having identified patients working in occupations placing them at risk of developing occupational asthma it is useful to determine if they are provided with regular and relevant health surveillance by their employer [4] and whether their employer provides access to an occupational health service.
A properly designed health surveillance programme supervised by a specialist occupational physician should identify suspected cases of occupational asthma or rhinitis and refer to expert units for further testing. It is important that cases are properly investigated in an expert unit to avoid patients being mislabelled and experiencing unnecessary changes to their work arrangements.
We therefore also offer another significant reason why the diagnosis is missed. Small and medium-sized enterprises (SMEs) account for 99.9% of all UK private sector businesses and employ 15.6 million people (60% of private sector employment). [5] An SME is less likely to provide access to occupational health care. [6]
Doctors should persuade the patient to report their problem to their employer so that they can arrange occupational health advice and a suitable and sufficient risk assessment. Doctors should also advise patients that their employer has a legal duty under the Reporting of Injuries, Diseases and Dangerous Occurrences Regulations (RIDDOR) 2013 to report cases of occupational asthma to the Heath and Safety Executive. They may also be entitled to Industrial Injury Disablement Benefit.
1. Feary J, Pinnock Hi, Cullinan P. Occupational asthma BMJ 2016; 353 :i2658
2. Francis HC, Prys-Picard CO, Fishwick D, et al. Defining and investigating occupational asthma: a consensus approach. Occup Environ Med, 2007; 64: 361-5.
3. Nicholson PJ, Cullinan P, Burge PS & Boyle C. Occupational asthma: Prevention, identification & management: Systematic review & recommendations. British Occupational Health Research Foundation. London. 2010. http://www.bohrf.org.uk/downloads/OccupationalAsthmaEvidenceReview-Mar20... (Last accessed 8th July 2016)
4. Levy ML, Nicholson PJ. Occupational asthma case finding: a role for primary care. Br J Gen Pract 2004;54:731-3.
5. Business population estimates for the UK and regions 2015. Department for Business, Innovation and Skills. London. 14 October 2015. https://www.gov.uk/government/statistics/business-population-estimates-2015 (Last accessed 8th July 2016)
6. Nicholson PJ, Cullinan P, Burge S. Concise guidance: diagnosis, management and prevention of occupational asthma. Clinical Medicine 2012, 12: 156–9.
Competing interests: No competing interests
Whilst I can see the importance of diagnosing occupational asthma, I don't understand why all such patients should be referred to a specialist occupational respiratory physician. Am I missing something? Would it not be better only to refer those who are unable or unwilling to change their job?
Competing interests: No competing interests
Re: Occupational asthma
We thank Dr Nicholson and Dr Fox for their comments on our article and for highlighting that the definition of occupational asthma also includes irritant-induced occupational asthma (previously referred to as reactive airways dysfunction syndrome or ‘RADS’); these cases usually come to light after a single, toxic exposure in the workplace. We agree that Occupational Health (OH) services – delivered more often now by occupational health nurses than physicians - provide a valuable role in identifying patients with possible or definite occupational asthma. Since a significant proportion of the patients we see work for employers who do not provide an OH service it is important that those working in primary or secondary care are aware of the condition.
Dr Hawkins’s question about why all patients have to be referred to a specialist is also important; we note that Drs Nicholson and Fox endorse this. The diagnosis of OA is not easy to make in a non-specialist clinic and requires access to immunological testing and familiarity with the condition and at-risk occupations. A false positive diagnosis, for example, due to work-exacerbated asthma (which does not usually require a change in job) may be made resulting in unnecessary redeployment often with an adverse economic impact. As mentioned in our article, one case commonly heralds another so it is important that a precise diagnosis is made to identify others at risk.
Competing interests: No competing interests