Asthma and Respiratory Infections from Birth to Young Adulthood: The Espoo Cohort Study


 We applied the population-based prospective Espoo Cohort Study (n=2,568) to identify potential susceptibility of subjects with asthma to respiratory tract infections (RTIs). Information on the occurrence of asthma and of both upper and lower respiratory tract infections (URTIs and LRTIs) was collected with a questionnaire at the baseline, the 6 year- and the 20 year-follow-up studies, and from the National Health Registries. We estimated age- and sex-specific incidence rate differences (IRD) and incidence rate ratios (IRR) applying negative binomial regression. Meta-regression was used to summarize the age-specific IRRs from childhood to 27 years of age. Individuals with asthma at any age during the follow-up had an increased risk of URTIs (aIRD 72.6, 95% CI: 50.6, 94.7 per 100 person-year; aIRR: 1.27, 1.20, 1.35) and LRTIs (aIRD 25.5, 17.9, 33.1; aIRR 2.87, 2.33, 3.53) from childhood to young adulthood. In young adulthood, the association between asthma and URTIs was stronger in women than men, while such was not detected for LRTIs. We provide strong evidence that subjects with asthma experience more RTIs from preschool age up to young adulthood compared to those without asthma. Thus, they constitute a susceptible population for RTIs. Especially women with asthma are at high risk.