Early patterns of wheezing in asthmatic and nonasthmatic children.

The aim of this study was to describe the time patterns of wheezing in both asthmatic and nonasthmatic children during the first 36 months of life, and to determine whether there are asthma-related breakpoints in the incidence of wheezing. Data from a historical cohort of children followed from birth to 6 years (SLAM cohort) were used. Wheezing episodes until 36 months and asthma at 6 years were both recorded by a doctor. Monthly mean incidence rate of wheezing and rate ratio were calculated. Joinpoint regression models were built to identify breakpoints in the risk of wheeze. Complete information was available for 3739 children. Wheezing in the first 36 months was more frequent in asthmatic than in nonasthmatic children (rate ratio 2.62, 95% CI 1.81-3.78). Differences were appreciable within the first months and increased steadily thereafter because of a persistently high rate in asthmatic children. No breakpoint in the rate ratio could be identified. Asthmatic children exhibited a one-phase curve of incidence and nonasthmatic children exhibited a two-phase curve. However, children with allergic asthma also displayed a two-phase curve. There is no identifiable breakpoint during the first 36 months of life at which the incidence of wheezing in asthmatic children begins to stand out.