Synthesis when meta-analysis is not possible: approaches to grouping, presentation and synthesis

Article type
Authors
McKenzie J1, Brennan S2, Thomson H3, Ryan R4, Johnston R5
1Monash University
2Cochrane Australia, Monash University
3Cochrane Public Health Review Group, University of Glasgow
4Cochrane Consumers and Communication Review Group, La Trobe University
5Cochrane Musculoskeletal Review Group, Monash University
Abstract
Background: in reviews where meta-analysis is not used, authors commonly report results study-by-study or draw conclusions without reporting how they interpreted findings across studies. These approaches may leave decision makers to make sense of findings themselves, and undermine confidence in the evidence. There are many circumstances that may preclude the use of meta-analysis of effect estimates. For example, when there is incomplete information reported about the intervention effect estimates (e.g. missing standard errors), or inconsistency in the reported effect metrics across studies. Other commonly cited reasons for not using meta-analysis can often be addressed through grouping, such as when there is sparse data arising from studies reporting diverse interventions or outcome measures. This workshop will provide potential solutions for these circumstances and is based on new guidance in version 6 of the Cochrane Handbook for Systematic Reviews of Interventions (Chapters 3 and 12).

Objectives: in this workshop we will
1) consider options for grouping studies to facilitate synthesis, and
2) provide guidance on presentation and synthesis methods that can be used when meta-analysis of effect estimates is not possible (sometimes referred to as 'narrative synthesis').

Description: in this workshop we will use a mix of practical exercises, interactive examples, and presentation to:
1) discuss scenarios that may preclude meta-analysis;
2) explore options for structuring reviews to facilitate syntheses (by grouping interventions and outcomes using taxonomies and frameworks);
3) present other synthesis and presentation methods, along with their advantages and disadvantages and guidance on when to use which approach; and
4) provide suggestions for describing the results of the synthesis.

Participants will work through an example examining approaches to synthesise data on patient satisfaction with care. Planning for circumstances that may preclude meta-analysis can ensure that review authors make the best use of available data and produce more useful syntheses for decision makers.