OBJECTIVES:

To identify existing guidelines or recommendations regarding the use of real-world evidence (RWE) in meta-analyses (MAs) and to summarize the limitations of using RWE in MAs.

METHODS:

A literature search was performed on April 2017 in MEDLINE/Embase, the Cochrane Library and other sources. No specific inclusion and exclusion criteria were applied, and no restrictions in timeframe, language, or geographical scope were imposed.

RESULTS:

The search strategy identified 1,681 references; out of which 12 references were included.

Identified recommendations regarding the use of RWE in MAs were: 1) it may be useful to extract and analyse adjusted results because confounding is expected in observational studies; 2) testing heterogeneity in observational studies is important as it may minimize the potential for bias and generate hypotheses for future research; 3) to conduct the search in at least 2 bibliographic databases when conducting MAs of observational studies to provide a thorough summary of the existing literature; 4) the Meta-analysis Of Observational Studies in Epidemiology (MOOSE) checklist is a 35-item checklist developed to address observational study limitations and allow for more standardized reporting of MAs of observational studies.

However, 1) no formal guidelines were found regarding the use of RWE in MAs; 2) no consensus was found on a preferred instrument for the assessment of RWE; 3) critical appraisal of RWE is often omitted from Health Technology Assessment submissions.

CONCLUSIONS:

The inclusion of RWE in MAs facilitates the confirmation of conclusions drawn from randomized controlled trials and may reassure decision-makers that the findings can be extrapolated to real-world populations. However, qualitative and quantitative bias corrections may coexist in MAs of observational studies. Reviewers should select the most appropriate checklist to match the study designs identified in a particular systematic review.