CRD Summary: The review found a significantly lower rate of clinically important bleeding when using proton pump inhibitors rather than histamine-2 receptor antagonists in the prevention of stress-related mucosal disease in critically ill patients. Rates of nosocomial pneumonia were similar. The reliability of the authors’ conclusions is unclear due to some methodological weaknesses and differences between the small number of studies.

[Included studies were of omeprazole compared with ranitidine, famotidine or cimetidine.]

CRD Commentary: The review addressed a well-defined question in terms of participants, interventions, study design and relevant outcomes. Relevant databases were searched, but it appeared that unpublished studies were not considered and publication bias was not assessed. Only studies published in English were identified, which implied that studies published in other languages were excluded. Study quality was assessed using suitable criteria. Validity assessment and data extraction were carried out with efforts to reduce error and bias; it was unclear whether this applied to other aspects of the review process. Relevant study and patient details were reported, but no details of the age or sex of the patients were given. Little detail was given of the method used for meta-analysis. Statistical heterogeneity was assessed and there was evidence for heterogeneity with the primary outcome. The reliability of the authors' conclusions are uncertain due to lack of reporting of some review methods, the small number and small sizes of included studies and differences between the studies.