There is limited understanding about risk factors for asthma, and few studies have presented an overall picture of factors associated with asthma subtypes in schoolchildren. The aim of this study was to evaluate risk factors and markers of asthma control associated with asthma subtypes up to preadolescence.
A Swedish birth cohort of 3015 children was followed for 12 yr using repeated parental questionnaires. At 8 yr, clinical investigation was performed, specifically evaluating lung function, allergic sensitization (IgE > 0.35 kUA /l), and body mass index (BMI). Children were categorized into three subtypes: transient asthma - asthma at 4 and 8, but not at 12 yr (n = 71), late-onset asthma - asthma at 12 yr, but not earlier (n = 103), and persistent asthma - asthma at 4, 8 and 12 yr (n = 125).
At 8 yr of age, high BMI (>85th percentile), sensitization, and rhinitis were significantly associated with late-onset asthma (p