Umbrella review of 42 systematic reviews with meta-analyses: the safety of proton pump inhibitors

Background Proton pump inhibitors (PPIs) are widely used to treat and prevent acid-related disorders. Despite high efficacy, PPI safety has been increasingly scrutinised. However, no comprehensive review summarising investigations of various adverse events is available. Aims To perform an umbrella review to comprehensively assess associations between adverse events and PPI use. Methods In accordance with PRISMA, an umbrella review of systematic reviews with meta-analyses was conducted. PubMed and EMBASE were searched from 2015 to July 2019. AMSTAR 2 and GRADE were used to assess quality and certainty of evidence. Author-reported quality assessments were also reviewed. Results Forty-two systematic reviews with meta-analyses, supported predominantly by observational evidence, were included. The most comprehensive studies reported statistically significant associations with PPI use for several outcomes, including: fractures (eg, hip; RR = 1.20; 95% CI = 1.14-1.28; n = 2 103 800), kidney disease (eg, acute kidney injury; RR = 1.61; 95% CI = 1.16-2.22; n = 2 396 640), infections (eg, Clostridioides difficile; OR = 1.99; 95% CI = 1.73-2.30; n = 356 683), gastric cancer (OR = 2.50; 95% CI = 1.74-3.85; n = 943 070) and gastrointestinal events (eg, fundic gland polyps; OR = 2.46; 95% CI = 1.42-4.27; n = 40 218). No associations with non-gastric cancers, or neurological disease were concluded, with conflicting evidence for cardiovascular outcomes. Certainty based on GRADE was very low for most outcomes. Conclusions This review identified several published associations between PPIs and adverse outcomes, however, further investigation is needed to understand their clinical significance and the likelihood of causal relationship. If higher quality evidence is generated substantiating the potential risks, it may be necessary for clinicians to consider alternative treatment strategies, especially when PPI efficacy is suboptimal.