Association between Helicobacter pylori and risk of childhood asthma: a meta-analysis of 18 observational studies.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of observational studies
PubMed 33630702 · doi:10.1080/02770903.2021.1892752
What was done
A systematic literature search and meta-analysis were performed to evaluate the association between Helicobacter pylori infection and childhood asthma. Data extraction was conducted independently and in duplicate, and analyses were performed using STATA. Subgroup analyses evaluated CagA strain status, study design, participant age, geographical region, and H. pylori detection method.
What was found
Eighteen moderate-to-high quality observational studies with 17,196 children were analyzed. Overall, H. pylori infection was significantly inversely associated with childhood asthma (OR = 0.68; 95% CI, 0.54-0.87; P = 0.002). In four studies evaluating CagA status, the negative association was statistically significant for CagA(+) strains (OR = 0.58; 95% CI, 0.35-0.96; P = 0.034) but not for CagA(-) strains (OR = 0.52; 95% CI, 0.12-2.28; P = 0.387). No significant subgroup differences were found by study design, participant age, region, or diagnostic method. Egger's and Begg's tests showed no significant publication bias (P = 0.162 and P = 0.198, respectively).
Why it matters
This study strengthens observational evidence supporting the hygiene hypothesis, showing that childhood colonization with virulent H. pylori strains is associated with reduced asthma risk.
Limits
The included literature is entirely observational, precluding causal inference and leaving results vulnerable to residual confounding (such as antibiotic use or socioeconomic factors). Only four studies evaluated CagA strain status, yielding wide confidence intervals for strain-specific estimates.
Cited by
- supports There is an inverse correlation between Helicobacter pylori infection and the incidence of childhood asthma.