Background Quality improvement collaboratives (QIC) have proliferated internationally, but there is little empirical evidence for their effectiveness.

Method We searched Medline, Embase, CINAHL, PsycINFO and the Cochrane Library databases from January 1995 to December 2014. Studies were included if they met the criteria for a QIC intervention and the Cochrane Effective Practice and Organisation of Care (EPOC) minimum study design characteristics for inclusion in a review. We assessed study bias using the EPOC checklist and the quality of the reported intervention using a subset of SQUIRE 1.0 standards.

Results Of the 220 studies meeting QIC criteria, 64 met EPOC study design standards for inclusion. There were 10 cluster randomised controlled trials, 24 controlled before-after studies and 30 interrupted time series studies. QICs encompassed a broad range of clinical settings, topics and populations ranging from neonates to the elderly. Few reports fully described QIC implementation and methods, intensity of activities, degree of site engagement and important contextual factors. By care setting, an improvement was reported for one or more of the study’s primary effect measures in 83% of the studies (32/39 (82%) hospital based, 17/20 (85%) ambulatory care, 3/4 nursing home and a sole ambulance QIC). Eight studies described persistence of the intervention effect 6 months to 2 years after the end of the collaborative. Collaboratives reporting success generally addressed relatively straightforward aspects of care, had a strong evidence base and noted a clear evidence-practice gap in an accepted clinical pathway or guideline.

Conclusions QICs have been adopted widely as an approach to shared learning and improvement in healthcare. Overall, the QICs included in this review reported significant improvements in targeted clinical processes and patient outcomes. These reports are encouraging, but most be interpreted cautiously since fewer than a third met established quality and reporting criteria, and publication bias is likely.