Infant antibiotic use and wheeze and asthma risk: a systematic review and meta-analysis.

Our aim was to systematically review and meta-analyse longitudinal studies on antibiotic use and subsequent development of wheeze and/or asthma with regards to study quality, outcome measurement, reverse causation (RC; wheezing/asthma symptoms have caused prescription of antibiotics) and confounding by indication (CbI; respiratory tract infections leading to antibiotic use may be the underlying cause triggering asthma symptom development). English-language papers and studies published before November 1, 2010 with longitudinal observational design were included. Study quality was assessed using the Newcastle-Ottawa scale. We identified 21 longitudinal studies. The effect of antibiotic use on wheeze/asthma risk varied between studies. 18 studies were eligible for meta-analysis showing pooled OR 1.27 (95% CI 1.12-1.43) for wheeze/asthma. When we eliminated studies with possible RC and CbI, the pooled risk estimate in the nine remaining studies was attenuated to OR 1.12 (95% CI 0.98-1.26). Definition of wheeze/asthma and age at follow-up differed between studies. Three studies focused on wheeze/asthma beyond 5-6 yrs of age with the presence of active symptoms and/or medication (pooled OR 1.08, 95% CI 0.93-1.23; dominated by one study). RC and CbI lead to overestimation of the association between antibiotic use and subsequent development of wheeze/asthma. Association was weak when fully adjusted for these types of bias. Heterogeneity of disease definition between studies could affect the results.