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BRITISH SOCIETY FOR ALLERGY AND CLINICAL IMMUNOLOGY

A survey was carried out in a population of 1391 middle-aged persons who attended a health clinic. They were asked to complete a questionnaire, one of the questions being 'Have you ever had asthma?'. The overall prevalence of ever having had asthma was 5 6%. In those who reported that they had had asthma which began before the age of 10 years a significant association was found with eczema, skin test reactivity and a history of symptomatic reaction to house dust. In those whose asthma had begun between the ages of 10 and 30 years, a significant association was found with a family history of hay fever or other atopic diseases. In patients reporting that their asthma had begun after the age of 30 years, no significant association was found with any of these factors but surprisingly there was a significant association with a history of symptomatic reaction to particular animals. This late onset form of asthma was found to occur significantly more commonly in men than in women. The findings of this survey suggest that those middle-aged persons who report that they have ever had asthma on a questionnaire have experienced a symptom common to a number of different diseases rather than a symptom which can be regarded as exclusive to a single disease entity. This may explain some of the confusing findings of epidemiological research. Before any inferences can be made from differences found between populations in the prevalence of asthma, it is essential to scrutinise their methodology, particularly whether the surveys were of point-prevalence or cumulative-prevalence and the age-range of the subjects who were studied.