Systematic review and meta-analysis of the possible association between pharmacological gastric acid suppression and spontaneous bacterial peritonitis

Background Observational studies have presented conflicting results with regard to an association between gastric acid suppression and spontaneous bacterial peritonitis (SBP). Our aim was to carry out a meta-analysis investigating the possible association between the use of proton pump inhibitors or H2-receptor antagonists and SBP. Methods We searched several databases from inception through 15 December 2014 to identify observational studies that provided data on the association of gastric acid suppression with SBP as their primary outcome, and carried out random effects meta-analyses. Results Fourteen observational studies (six case-control and eight cohort) evaluating the association between proton pump inhibitors and SBP revealed a pooled odds ratio (OR) of 2.32 [95% confidence interval (CI) 1.57-3.42, I2= 82%]. The subgroup analysis based on study design revealed a pooled OR of 2.52 (95% CI 1.71-3.71, I2=16%) for case-control studies, and a pooled OR of 2.18 (95% CI 1.24-3.82, I2= 89%) for cohort studies. Sensitivity analysis including only the peer-reviewed publications in the cohort subgroup revealed a pooled OR of 1.49 (95% CI 1.15-1.95, I2=27%). The subgroup analysis for highquality studies revealed a pooled OR of 1.49 (95% CI 1.19-1.88, I2= 21%). The pooled OR for H2-receptor antagonists and SBP was 1.93 (95% CI 1.15-3.24, I2= 0%). Conclusions There appear to be statistically significant, but quantitatively small, associations between gastric acid suppression and SBP. However, the magnitude of the possible association diminished when analysis focused on higher quality data that were more robust. Furthermore, the quality evidence in support of the association, as per the GRADE framework, was very low.