Early-life respiratory tract infections and risk of lower lung function and asthma at school-age. The generation R study

Abstract

Background: Early-life respiratory tract infections could lead to higher airway sensitization affecting airway obstruction and hyperreactivity, and subsequently asthma in later life. Aim: We examined the associations of early-life respiratory tract infections with lung function and asthma in school-aged children. Methods: This study among 5,388 children was embedded in a population-based prospective cohort study. Information on physician-attended upper and lower respiratory tract infections was obtained by questionnaires from age 6 months to 6 years and grouped into respiratory tract infections ≤3 and >3 years. At age 10 years FEV 1 , FVC, FEV 1 /FVC and FEF 75 were measured and information on physician-diagnosed asthma was obtained by a questionnaire. Regression models were accounted for socioeconomic, lifestyle and growth factors, and early life wheezing. Results: Upper respiratory tract infections were not associated with lower lung function or risk of asthma. Lower respiratory tract infections ≤3 years were associated with lower FEV 1 , FVC and FEV 1 /FVC (Z score (95% CI): -0.22 (-0.32, -0.12), -0.14 (-0.23, -0.04) and -0.11 (-0.21, -0.02)), and a higher risk of asthma (OR (95% CI): 3.42 (2.26, 5.16)), compared with no lower respiratory tract infections. Lower respiratory tract infections >3 years were associated with a higher risk of asthma (2.55 (1.60, 4.07)) only. Cross-lagged modeling showed that the associations were not in the opposite direction. Conclusions: Early-life lower respiratory tract infections are most consistently associated with lower lung function and increased risk of asthma in school-aged children, while upper respiratory tract infections are not.