Association Between ABO Blood Groups and Helicobacter pylori Infection: A Meta-Analysis.

There is no consensus among the existing literature on the relationship between ABO blood groups and risk of Helicobacter pylori infection. However, histo-blood group carbohydrates are proposed to influence the risk of acquiring this pathogen via effects on adhesion to the gastric mucosa. The objective of this meta-analysis was to evaluate the association between ABO blood groups and H. pylori infection. All relevant epidemiological studies published in English (up to October 2017) was retrieved through an extensive systematic literature search of MEDLINE/PubMed databases. Pooled estimates of effects were obtained through the use of fixed and random effects meta-analyses. Individuals with O blood group were more likely to be infected with H. pylori (pooled odds ratio (OR) 1.163; 95% confidence interval (CI) 1.074-1.259; P < 0.001). While individuals with B and AB blood group were less likely to be infected with H. pylori (OR 0.831; 95% CI 0.738-0.935; P = 0.002 and OR 0.709; 95% CI 0.605-0.832; P < 0.001, respectively). The results from this meta-analysis of observational studies suggest an estimated 16.3% increased odds of H. pylori infection amongst individuals with the O blood group. If this observed association is causal, a better understanding of the underlying mechanisms could provide indications to potential prevention strategies for H. pylori infection.