Objective To provide an overview of effective interventions aimed at reducing rates of adverse events in hospitals.

Design Systematic review of systematic reviews.

Data sources PubMed, CINAHL, PsycINFO, the Cochrane Library and EMBASE were searched for systematic reviews published until October 2015.

Study selection English-language systematic reviews of interventions aimed at reducing adverse events in hospitals, including studies with an experimental design and reporting adverse event rates, were included. Two reviewers independently assessed each study's quality and extracted data on the study population, study design, intervention characteristics and adverse patient outcomes.

Results Sixty systematic reviews with moderate to high quality were included. Statistically significant pooled effect sizes were found for 14 types of interventions, including: (1) multicomponent interventions to prevent delirium; (2) rapid response teams to reduce cardiopulmonary arrest and mortality rates; (3) pharmacist interventions to reduce adverse drug events; (4) exercises and multicomponent interventions to prevent falls; and (5) care bundle interventions, checklists and reminders to reduce infections. Most (82%) of the significant effect sizes were based on 5 or fewer primary studies with an experimental study design.

Conclusions The evidence for patient-safety interventions implemented in hospitals worldwide is weak. The findings address the need to invest in high-quality research standards in order to identify interventions that have a real impact on patient safety. Interventions to prevent delirium, cardiopulmonary arrest and mortality, adverse drug events, infections and falls are most effective and should therefore be prioritised by clinicians.