A historical cohort study was performed in order to assess the hypothesis that even mild bronchiolitis in infancy is a predictor of wheezing later in childhood. Subjects who had experienced bronchiolitis and a matched control group were compared in terms of reported wheezing 8 years later. A highly significant difference was found between the bronchiolitis group and the control group in terms of current wheezing ( P .0001, relative risk 3.24). This difference was maintained after adjusting for many potentially confounding variables including family history of allergy and other allergic manifestations in the child. Results suggested that 13.6% of a normal practice population in the age range 6 to 9 years currently wheeze, but that 44.1% of children who experienced bronchiolitis currently wheeze. Based on the incidence of bronchiolitis (4.27/100 children in their first 2 years of life) and the relative odds for wheezing derived from a logistic regression model including variables that measured passive smoking, genetic tendency to wheeze, and bronchiolitis, calculations of attributable risk suggested that wheezing in 9.4% of the population of children who currently wheeze was attributable to bronchiolitis.
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