Table 4.

Baseline Predictors of the Persistence of Severe Asthma from Late Adolescence to Early Adulthood (N = 682)

Characteristic	Persistence of Severe Asthma [OR (95% CI)]	P Value
Postbronchodilator FEV1/FVC ratio	0.84 (0.79–0.90)	<0.0001
Maternal smoking during pregnancy	3.17 (1.18–8.53)	0.02
Parental asthma	2.09 (0.97–4.50)	0.06
Hay fever	0.50 (0.22–1.12)	0.09

Definition of abbreviations: CI = confidence interval; OR = odds ratio; PC₂₀ = provocative concentration resulting in a 20% fall in the FEV₁.

Multinomial logistic regression includes all predictors that resulted from our model by using stepwise selection while adjusting for the following covariates: age at randomization, sex, ethnicity (White or other), treatment group, clinic of enrollment, duration of asthma, severity at baseline (mild or moderate persistent asthma as assessed by a physician), and any environmental skin prick test reactivity. Candidate variables included the following: secondhand smoke exposure, maternal smoking during pregnancy, body mass index percentile, hay fever, eczema, food allergy, parental asthma, sensitized and exposed to any environmental allergens, bronchial hyperreactivity, prebronchodilator FEV₁/FVC ratio, postbronchodilator FEV₁/FVC ratio, bronchial hyperresponsiveness to methacholine challenge (log₁₀ of PC₂₀), serum total IgE (log₁₀), and serum absolute eosinophil count (log₁₀).