A typology of systematic reviews for synthesising evidence on health care

ObjectivesThe objectives of this paper are to (a) Review published references to systematic reviews; (b) offer a typology of systematic reviews for synthesising evidence on health care; and (c) summarise the guides for designing, reporting and appraising the reviews. BackgroundSystematic reviews play a role in finding, synthesising, transferring and implementing evidence for healthcare policy, practice guidelines and allocation of health resources. They have been particularly successful in confirming or synthesising evidence for health care by meta-analysing aggregated data from multiple randomised controlled trials. However, concerns about the limitations of evidence from controlled trials have prompted interest in other review methods capable of locating and appraising evidence from more diverse, and possibly more realistic, healthcare situations. MethodsAn iterative citation-tracking process with Google Search and grey literature identified 204 papers on previous typologies and methods of systematic reviews. Results and ConclusionsThere are six types of systematic reviews: narrative; meta-analysis; scoping; qualitative; umbrella; and realist. Each type has distinct objectives, characteristics and attributes, but with much overlapping of methods and guides. Sensitivity to the need for qualitative evidence on complex human responses to ill-health and health care has broadened the objectives and methods of health-related systematic reviews to find, appraise and synthesis useful evidence for practice guidelines, healthcare policy and allocation of health resources.