Association between and risk of childhood asthma: a meta-analysis of 18 observational studies.

The association between () and childhood asthma is unclear. Thus, the aim of this study was to explore the association between and childhood asthma. A literature search, study selection, and data extraction were performed independently and in duplicate. Data were analyzed using STATA software. Eighteen studies enrolling 17,196 children were analyzed. All studies were of moderate-to-high quality. Four studies subcategorized infection according to CagA status. Overall, there was a significant negative association between and risk for childhood asthma (OR = 0.68; 95% CI, 0.54-0.87;  = 0.002), with no/marginal publication bias identified by the Egger's test and the Begg's test ( = 0.162 and  = 0.198, respectively). The observed inverse association persisted for CagA(+) strains of (OR = 0.58; 95% CI, 0.35-0.96;  = 0.034) but not for CagA(-) strains (OR = 0.52; 95% CI, 0.12-2.28;  = 0.387). There was no significant difference between studies with respect to study design, participant age, geographical region, and method of measuring . The evidence suggests that infection, particularly CagA(+) infection, is inversely associated with the risk of childhood asthma. Supplemental data for this article can be accessed at publisher's website.