Table 4.

Critical and non-critical items according to the AMSTAR-2 critical appraisal tool

Critical items

Non-critical items

Protocol registered before commencement of review Adequacy of the literature search Justification for excluding individual studies Risk of bias from individual studies being included in the review Appropriateness of meta-analytical methods Consideration of risk of bias when interpreting the results of the review Assessment of presence and likely impact of publication bias

PICO used for research question/inclusion criteria Justification of study design inclusion Study selection completed in duplicate Data extraction completed in duplicate Adequate description of included studies Sources of funding of included studies Impact of risk of bias on meta-analysis or other evidence synthesis assessed Satisfactory explanation and discussion of heterogeneity of results Conflicts of interest of authors declared

AMSTAR-2, Assessing the MeaSurement Tool to Assess systematic Reviews Version 2; PICO, population, intervention, control group and outcome.