What causes cryptogenic fibrosing alveolitis? A case-control study of environmental exposure to dust.

OBJECTIVE To investigate the role of occupational and domestic exposure to dust in the aetiology of cryptogenic fibrosing alveolitis. DESIGN Matched case-control study. SUBJECTS 40 Patients with cryptogenic fibrosing alveolitis and 106 community controls matched for age and sex who responded to a questionnaire. MAIN OUTCOME MEASURE Responses to self administered questionnaire asking about lifetime exposure to dust, animals, and smoke at home and at work. RESULTS The patients with cryptogenic fibrosing alveolitis were more likely to report occupational exposure to metal dust (matched odds ratio 10.97 (95% confidence interval 2.30 to 52.4), p less than 0.001) or wood dust (2.94 (0.87 to 9.90), p = 0.08), to have worked with cattle (10.89 (1.24 to 96.0), p = 0.01), and to have lived in a house heated by a wood fire (12.55 (1.04 to 114), p = 0.009). A history of smoking and social class based on occupation were not significantly related to disease state. CONCLUSION Environmental exposure to dust may be an important factor in the aetiology of cryptogenic fibrosing alveolitis.