Epidemiological study of wheeze, doctor diagnosed asthma, and cough in preschool children in Leicestershire.

To determine the cumulative prevalences of wheeze and doctor diagnosed asthma and the point prevalences of recurrent cough and wheeze in children aged 5 years and under. Questionnaire survey of population based random sample of children registered on regional authority's child health index for immunisation; questionnaire completed by parents. Leicestershire. 1650 white children born in 1985-9 who were surveyed in 1990. Cumulative prevalences of wheeze and doctor diagnosed asthma and point prevalences of recurrent cough and wheeze by age and sex. There were 1422 replies (86.2%; 726 for boys, 696 for girls). Overall, 11.0% (95% confidence interval 9.4% to 12.6%) of children had formally been diagnosed as having asthma, the cumulative prevalence in boys (12.7%) being somewhat higher than in girls (9.2%) (age adjusted odds ratio 1.47, p = 0.03). As expected, the cumulative prevalence of asthma increased significantly with age (7.5% (13/173) in children under 1 year, 15.9% (61/383) in children of 4 years and over; p < 0.001). The cumulative prevalence of wheeze overall was 15.6% (13.7% to 17.5%), being higher in boys (17.6%) than in girls (13.5%) (odds ratio 1.38, p = 0.03). The overall prevalence of recurrent cough without colds was 21.8% (19.6% to 23.9%), with a non-significant excess in boys (23.1% v 20.4%). The overall prevalence of wheezing attacks during the previous 12 months was 13.0% (11.3% to 14.8%) with a non-significant excess in boys (14.5% v 11.5%). These findings are baseline results and emphasise the importance of studying the age group of interest rather than relying on the recall of parents of school age children.