Factors Associated with Persistence of Severe Asthma from Late Adolescence to Early Adulthood

Rationale: Asthma in children generally starts as being mild but may progress to being severe and may stay severe for unknown reasons. Objectives: To identify factors in childhood that predict the persistence of severe asthma in late adolescence and early adulthood. Methods: The CAMP (Childhood Asthma Management Program) is, to our knowledge, the largest and longest asthma trial to date; it includes 1,041 children aged 5-12 years with mild to moderate asthma. We evaluated 682 program participants with analyzable data in late adolescence (age, 17-19 yr) and early adulthood (age, 21-23 yr). Measurements and Main Results: To best capture the cases of severe asthma, a status of severe asthma was defined by using criteria from the American Thoracic Society and the National Asthma Education and Prevention Program. Logistic regression with stepwise elimination was used to analyze the clinical features, biomarkers, and lung function that are predictive of the persistence of severe asthma. In late adolescence and early adulthood, 12% and 19% of the participants had severe asthma, respectively; only 6% at both time points had severe cases. For every 5% decrease in the postbronchodilator FEV₁/FVC ratio in childhood, the odds of the persistence of severe asthma increased by 2.36-fold (95% confidence interval [CI], 1.70-3.28; P < 0.0001); for participants with maternal smoking during pregnancy, the odds of the persistence of severe asthma increased by 3.17-fold (95% CI, 1.18-8.53; P = 0.02). A reduced-growth lung function trajectory was significantly associated with the persistence of severe asthma compared with a normal-growth lung function trajectory. Conclusions: Lung function and maternal smoking during pregnancy were significant predictors of severe asthma from late adolescence to early adulthood. Early interventions to preserve lung function may prevent disease progression.