Inverse Associations of Helicobacter pylori with Asthma and Allergy.

The study evaluated the associations of H pylori status with history of asthma and allergy and with skin sensitisation using data from 7663 adults. Adjusted odds ratios (ORs) for currently and ever having asthma, allergic rhinitis, allergy symptoms in the previous year, and allergen-specific skin sensitisation were computed comparing participants seropositive for cagA– or cagA+ strains of H pylori with those without H pylori. The presence of cagA+ H pylori strains was inversely related to ever having asthma, and the inverse association of cagA positivity with childhood-onset (age 15 years) asthma was stronger than that with adult-onset asthma. Colonisation with H pylori, especially with a cagA+ strain, was inversely associated with currently or ever having a diagnosis of allergic rhinitis, especially for childhood onset. Consistent inverse associations were found between H pylori colonisation and the presence of allergy symptoms in the previous year and sensitisation to pollens and molds. The observations support the hypothesis that childhood acquisition of H pylori is associated with reduced risks of asthma and allergy. Arch Intern Med. 2007;167(8):821-7.