Epidemiologic approaches for the identification of asthma.

Clinical, physiologic, and questionnaire approaches can be used to identify subjects with asthma in an epidemiologic investigation. Each method, however, may select differing subsets of the population. At present, a comprehensive asthma questionnaire is unavailable; the difficulty of defining asthma in operational terms has been a major obstacle in the development of such a questionnaire. This review describes the questionnaires prepared by the British Medical Research Council and the American Thoracic Society and suggests modifications.