Childcare attendance and Helicobacter pylori infection: systematic review and meta-analysis.

Helicobacter pylori infection is acquired predominantly during childhood. Childcare promotes interpersonal contact and may be an important determinant of infection. The aim was to quantify the association between childcare attendance and H. pylori infection in childhood or adolescence. PubMed was searched up to July 2012 to identify eligible studies. The DerSimonian and Laird method was used to compute summary odds ratio (OR) estimates and 95% confidence intervals (CIs); heterogeneity was quantified with the I statistic and explained through stratified analyses and metaregression. Sixteen studies compared participants attending childcare with those not exposed. The summary OR was 1.12 (95% CI: 0.82-1.52, I=77.4%). Summary estimates were similar for crude and adjusted estimates, and higher when the infection was evaluated in children of 3 years or younger (OR=2.00, 95% CI: 0.94-4.29, I=55.0%). Studies based on the detection of stool antigens yielded higher estimates (OR=2.65, 95% CI: 1.24-5.66, I=36.4%). Those conducted in settings with a high prevalence of H. pylori infection yielded stronger associations (OR=1.44, 95% CI: 0.94-2.20, I=74.3%). In multivariate metaregression, there was no significant association with any of these variables; taking them into account contributed to a reduction of I to 67%. The role of childcare as a risk factor for H. pylori infection is confirmed by our results, especially in settings with a high prevalence of infection. However, the association was moderate, and the effect of the type of childcare setting or the duration or the intensity of exposure was seldom addressed, leaving considerable scope for improving our understanding of how this modifiable exposure contributes towards H. pylori infection.