Abstract
Background Asthma is a heterogeneous disease and during adolescence the sex ratio of the asthma prevalence changes. Longitudinal population-based studies about clinical characteristics of asthma during adolescence are scarce.
Aim To characterize 19 year olds with asthma regarding lung function, co-morbidities, and severity in relation to age at asthma onset.
Method In a longitudinal study about asthma and allergic diseases within the Obstructive Lung Disease in Northern Sweden (OLIN) studies, a cohort of school children (n=3430) was followed annually from age 7-8y by completion of an extended ISAAC questionnaire. At age 19y, n=2861 (83% of original responders) participated in the questionnaire survey, and n=1884 in clinical examinations including skin prick tests (SPT) and spirometry.
Results At age 19y, the prevalence of current asthma was 11.4% among girls vs. 8.5% among boys, p<0.01. In asthmatics, 75% were sensitized (girls 68% vs. boys 84%; p=0.011), 40% had eczema, and 36% rhinitis. Girls tended to report more severe asthma, but not significantly. Age at onset of asthma differed by sex: 43% of the boys had onset before age 8y vs. 25% among girls, whereas 54% of the girls had onset after age 12y vs. 34% among boys (p<0.001). Among boys, mean FEV1% of predicted was 88% in those with onset before 8y, 92% between 8 and 12y, and 96% in those with onset after age 12y (p=0.021), but this pattern was not observed among the girls.
Conclusion Among 19 year old asthmatics, a greater proportion of boys were sensitized and boys also had earlier asthma onset than girls. Lower lung function was related to early asthma onset among asthmatic boys but not in girls.
- Copyright ©the authors 2016
