Many factors, including heredity, atopic status, and environment, have been implicated in the determination of asthma severity. Relatively little is known about the degree to which asthma duration influences asthma severity.
The Childhood Asthma Management Program (CAMP), consisting of 1041 children (age 8. 9 +/- 2.1 years at enrollment) with mild-to-moderate asthma, offers an opportunity to examine the relationship between asthma duration and asthma severity.
By using the extensive CAMP baseline cross-sectional data on asthma duration, spirometry, bronchial responsiveness, symptomatology, and markers of atopy, univariate and multivariate regression models were used to evaluate whether asthma duration is associated with asthma severity.
Duration of asthma in the study cohort from time of diagnosis until randomization into CAMP ranged from 0.3 to 12.1 years (mean, 5.0; SD, 2.7; median, 4.8). Asthma duration is associated in univariate analyses both with lower levels of several lung functions (P