A COMPARISON OF SOME OF THE CHARACTERISTICS OF PATIENTS WITH OCCUPATIONAL AND NON-OCCUPATIONAL ASTHMA

Occupational asthma is the most frequently diagnosed occupational lung disease reported to the SWORD (Surveillance of Work-related and Occup ational Respiratory Disease) scheme. However, diagnosing occupational asthma is not straightforward, and establishing a link with work may b e difficult. This study was undertaken to determine the differences be tween patients with occupational asthma and those with non-occupationa l asthma which might help in their diagnosis. information was collecte d using a self-completed questionnaire. Questionnaires were distribute d to 30 subjects aged 18-65 years at each of two clinics - one for pat ients with occupational asthma and one for those with cryptogenic and environmental asthma. Replies were received from 26 patients with occu pational asthma (87%) and 29 patients with non-occupational asthma (97 %). The age of onset was significantly higher for those with occupatio nal asthma (42.6 vs 20.7 years). Significantly more subjects with occu pational asthma reported improvement on holiday, whereas no significan t difference was found in the numbers reporting worsening of symptoms on work days. Those with occupational asthma were less likely to repor t seasonal variation in symptoms, exacerbation by allergies, pets and stress, or a family history of asthma. Subjects with occupational asth ma were more likely to become unemployed (50% vs 3%). Recognition of s ome of these features in a patient's history may help in the difficult task of differentiating occupational from non-occupational asthma, po tentially avoiding the need for exhaustive investigations in some pati ents. The high prevalence of holiday improvement among subjects with n on-occupational asthma suggested that domestic or environmental allerg ies arising outside the workplace may have been making an important co ntribution to ongoing symptoms in these subjects.