The protocol should detail how the reviewers plan to synthesize data extracted from included studies. The types of data it is anticipated will be synthesized should be consistent with the methods used for data collection and the included study designs. The review report should detail how the reviewers synthesized the data extracted from included studies and how it was applied consistently across all included studies.
As with all systematic reviews, there are various approaches to present the results, including a narrative, graphical or tabular summary, or meta-analysis (refer to the appropriate section below) (Munn, Tufanaru et al. 2014). There are some special considerations when conducting meta-analysis for questions related to etiology & risk.