In a European birth cohort study, lower respiratory tract infections during infancy were associated with school-age impaired lung function and asthma, upper tract infections with asthma.

How do respiratory tract infections during early life affect later lung function? As the issue remains controversial, researchers conducted a meta-analysis from 38 European birth cohorts involving 150,000 children born between 1989 and 2013, for whom information on recent respiratory tract infections at the ages of 6 months and 1, 2, 3, 4 and 5 years was available. Lung function (converted into sex-, age-, height- and ethnicity-adjusted Z-scores based on Global Lung Initiative reference values) and asthma were evaluated at school age.

Upper and lower respiratory tract infections were most prevalent at age 1 year (mean, 63% [upper] and 23% [lower]) and declined thereafter to age 5 years (43% and 15%). Lower, but not upper, respiratory tract infections at all ages were associated with significantly lower one-second forced expiratory volume (FEV₁) and FEV₁/forced vital capacity (FVC) at school age (median age, 7 years; Z-score difference range, −0.09 to −0.30). Furthermore, both upper and lower tract infections were associated with subsequent asthma (odds ratios, 1.25 and 2.10, respectively). The results were robust in sensitivity analyses and after correction for potential confounders (e.g. maternal age, smoking during pregnancy, history of asthma, child’s sex, gestational age at birth, birthweight, season of birth, breastfeeding, daycare attendance).

Comment: A logical consequence of these data would be to increase efforts at preventing respiratory tract infections in young children, especially those involving the lower tract. This would represent an additional argument for promoting the pneumococcal vaccine in childhood, even though the study was not designed to report the beneficial effects of vaccination.
THOMAS GLÜCK, MD
Professor of Medicine, University of Regensburg, Chief, Department of Medicine, District Hospital Trostberg, and Chief, Infectious Diseases Consulting Service, Traunstein and Trostberg, Bavaria, Germany.

van Meel ER, et al. Early-life respiratory tract infections and the risk of school-age lower lung function and asthma: a meta- analysis of 150000 European children. Eur Respir J 2022 Apr 29; e-pub (https://doi.org/10.1183/13993003.02395-2021).

This summary is taken from the following Journal Watch title: Infectious Diseases.