- Design
- Systematic review with meta-analysis of observational studies
- Population
- 35 paediatric studies; 14 on asthma
- Primary outcome
- Association of H. pylori infection with asthma and immune-mediated diseases
- Effect
- Asthma OR 0.75 (95% CI 0.54–1.05); I² 67%
A long-standing hypothesis holds that childhood H. pylori infection may protect against allergic disease. This systematic review of 35 paediatric studies from the past 12 years examined asthma, coeliac disease, eosinophilic oesophagitis, inflammatory bowel disease and other immune conditions.
In the asthma meta-analysis, infection was not significantly associated with asthma (OR 0.75, 95% CI 0.54–1.05), with substantial heterogeneity. An inverse association appeared only in studies diagnosing infection by breath or stool antigen tests and in those at higher risk of bias; histology-based and low-bias studies showed none. Findings for coeliac disease and inflammatory bowel disease were mixed, and no clear pattern emerged elsewhere.
The practical upshot is that there is no good paediatric reason to leave a symptomatic, confirmed H. pylori infection untreated on the theory that it guards against allergy.
- Do not withhold treatment of confirmed, symptomatic H. pylori in a child to protect against asthma.
- Test for H. pylori in children only when there is a clear indication, such as suspected peptic ulcer.
- Use endoscopy-based diagnosis where guidelines call for it in children.
- Explain to parents that current evidence does not show a protective effect.
Why it matters
The idea that H. pylori protects children from allergy still shapes some decisions, and the better studies do not support it.
Don't overread it
Observational studies cannot settle cause either way; the absence of an association is not proof of no effect.
The statistics, in plain English
An OR of 0.75 suggests 25% lower odds, but the interval reaches 1.05, so no association is also compatible. When the apparent effect is found only in weaker studies, that usually points to bias rather than biology.
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