Association between Helicobacter pylori infection and risk of nonalcoholic fatty liver disease: An updated meta-analysis

Background: Recent studies that have examined the association between Helicobacter pylori infection and risk of nonalcoholic fatty liver disease (NAFLD)have produced conflicting data. We have performed a systematic review and meta-analysis to assess the association between H. pylori infection and risk of NAFLD. Methods: We searched PubMed, Web of Science and Scopus databases using predefined keywords to identify observational studies (published up to November 2018), in which NAFLD was diagnosed by histology, imaging or biochemistry. Data from selected studies were extracted and meta-analysis was performed using random-effects modeling. The statistical heterogeneity among studies (I 2 -index), subgroup analyses and the possibility of publication bias were assessed. Results: Thirteen observational (11 cross-sectional/case-control and 2 longitudinal)studies involving a total of 81,162 middle-aged individuals of predominantly Asian ethnicity (47.5% of whom had H. pylori infection diagnosed by urea breath test, faecal or serological tests)were included in the final analysis. Meta-analysis of data from cross-sectional and case-control studies showed that H. pylori infection was associated with increased risk of prevalent NAFLD (n = 11 studies; random-effects odds ratio [OR]1.20, 95% CI 1.07–1.35; I 2 = 59.6%); this risk remained significant in those studies where analysis was fully adjusted for age, sex, smoking, adiposity measures, diabetes or dyslipidemia (random-effects OR 1.19, 95% CI 1.07–1.32, I 2 = 0%). Meta-analysis of data from longitudinal studies showed that H. pylori infection was also associated with increased NAFLD incidence (n = 2 studies; random-effects hazard ratio 1.14, 95% CI 1.05–1.23; I 2 = 0%). Sensitivity analyses did not alter these findings. Funnel plot did not reveal significant publication bias. Conclusions: H. pylori infection is associated with mildly increased risk of both prevalent and incident NAFLD in middle-aged individuals. More prospective studies, particularly in non-Asian populations, and mechanistic studies are required to better elucidate the link between chronic H. pylori infection and NAFLD.