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Diagnosis of occupational asthma
Questionnaires administered in general populations have shown that about 10–15% of subjects with asthma report that their asthma is worse at work.1 A proportion of these subjects may show what is called occupational asthma (OA)—that is, asthma caused by an agent inhaled at work. It is important to confirm or exclude a diagnosis of OA for at least two reasons: (1) if a worker with OA continues to be exposed to the causal agent, this can lead to worsening of asthma and diminishes the likelihood of resolution; it has been shown consistently that the duration of exposure with symptoms is the principal determinant of persisting asthma after avoidance of exposure2,3 and (2) removing a worker from her/his workplace has serious psychosocioeconomic consequences for the worker, often when young, and also for the employer and society.4 Advice to leave a job in these circumstances needs to be based on a secure foundation. At a time when expensive high‐technology imaging testing is available for all sorts of diseases, it is frustrating that frequently advice to a worker to stay at work or to leave is based only on the clinical history.
In this issue of the journal, Francis et al5 present interesting results of a survey carried out among expert clinicians who run specialist OA clinics in the UK. In a postal survey followed by an interview, nine experts examined a list of 42 indicators related to the definition of OA and resources to be made available in specialised clinics. Concerning the definition, interestingly, as also proposed by others,6,7 71% of the experts agreed that OA should encompass two varieties of work‐related asthma: those with and without a latency period, the former being induced through “sensitisation” and the latter being secondary to an acute exposure to an irritant product. The prioritisation of the 28 indicators, which concerned the investigation of OA, reached slightly less consensus (64%). Objective testing of OA encompasses a combination of several tools, which can often be schemed in a stepwise fashion.8 These include immunological assessment, tests for airway calibre and non‐specific and specific responsiveness, and evaluation of inflammation. In this regard, results of this survey are of interest, although possibly of surprise in some aspects:
This survey did not obtain opinions on the way in which the stepwise approach recommended in the investigation of OA could be used and applied.14 There might well be diverging opinions on possible schemes. A point that was not clarified was whether experts who were interviewed proposed the tests that were used in their respective centres. This information would have depicted preferences and real‐life priorities. Moreover, one wonders to what extent the results of this survey were influenced by the recent publication of the British Occupational Health Research Foundation guidelines.6 It is certainly to be hoped that this survey represents a first essential step in proposing standards of quality requirements for the accreditation of centres in which OA is investigated, which is a crucial aspect for improving the diagnosis of this condition.
Competing interests: None declared.