Practice Easily missed?

Occupational asthma

BMJ 2016; 353 doi: https://doi.org/10.1136/bmj.i2658 (Published 03 June 2016) Cite this as: BMJ 2016;353:i2658
  1. Johanna Feary, senior clinical research fellow1,
  2. Hilary Pinnock, reader and general practitioner2 3,
  3. Paul Cullinan, professor of occupational lung disease1
  1. 1Department of Occupational and Environmental Medicine, Royal Brompton and Harefield NHS Foundation Trust, London SW3 6LR, UK
  2. 2Asthma UK Centre for Applied Research, Usher Institute of Population Health Sciences and Informatics, University of Edinburgh, Medical School, Edinburgh, UK
  3. 3Whitstable Medical Practice, Whitstable, UK
  1. Correspondence to: J Feary j.feary{at}imperial.ac.uk

A 22 year old man thought he might have hay fever. Several months later his general practitioner diagnosed asthma. It later emerged that his symptoms were associated with his work in a bakery, and he was referred to an occupational lung disease specialist who diagnosed occupational asthma.

What is occupational asthma?

Occupational asthma is caused by an immune reaction to specific agents that are inhaled in the workplace. It differs from asthma that is aggravated at work by non-specific factors—for example, exposure to dusts or fumes, cold air, physical exertion, and even shift patterns.

Offer all adults with suspected occupational asthma referral to an occupational lung disease specialist. Diagnosis is based on a history of exposure to a sensitising agent and immunology tests, peak flow measurements, and specific challenge tests if appropriate.

How common is occupational asthma?

About one in seven cases of adult onset or recrudescent asthma will have a link with work, but it is unknown what proportion is “occupational asthma.”1

About 400 causative agents are recognised, although fewer than a dozen are responsible for most cases. These include proteins (“high molecular mass” agents) that induce a specific IgE response and certain reactive chemicals (“low molecular mass” agents) for which the mechanism is often less clear (table 1).

View this table:
Table 1

Common causes of occupational asthma

Why is it missed?

GPs may not routinely explore the role of occupation in patients with asthma or rhinitis. In a UK case series of almost 100 patients with occupational asthma, the mean interval between presentation to primary care and referral for specialist assessment was four …

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