4.4.7.5 Data synthesis

The review report should explicitly specify how the data were combined and reported. Essentially, the review report should provide the details about all preformed analyses and their justifications. The synthesis approaches by which studies were combined should be described in as much detail as is reasonably possible and to enable them to be reproduced.

If meta-analysis was performed, the review report should specify the details regarding the performed meta-analyses. The report should specify:

• the objectives of the meta-analysis

• the effect size used (OR, RR, etc.)

• the meta-analysis model (fixed effects model or random effects model) and the justification

• the meta-analysis method (Peto method etc.) and the justification

• the statistical testing procedures used for the exploration of statistical heterogeneity (such as Q Cochran test) and the rules used for the interpretation of the results

• the statistical indicator used for the quantification of statistical heterogeneity (such as I²) and the rules used for the interpretation of the results

• the performed sensitivity analyses

• the performed subgroup analyses