Table 2 Methodological quality checklist

1. Is there a well-defined question?

  The question should define at least the participants, the intervention, outcomes and the study designs.

2. Is there a defined search strategy?

  The search strategy should include at least one named database combined with reference checking, hand searching, citation follow-up or expert contact.

3. Are inclusion/exclusion criteria stated?

  The review should make the grounds for study inclusion and exclusion transparent in terms of participants, interventions, outcomes and study designs.

4. Are study designs and number of studies clearly stated?

  The review should outline the designs of included studies and make it clear which and how many studies are in the final synthesis.

5. Have the primary studies been quality assessed?

  The quality assessment process should be transparent in the review and should clearly describe which quality appraisal tool is used, and the relative quality of the included study.

6. Have the studies been appropriately synthesised?

  The review should use either meta-analysis or narrative synthesis depending on the heterogeneity and methodological quality.

7. Has more than one author been involved in each stage of the review process?

  To minimise bias, at least two reviewers should be involved in each stage of the review process (study selection, data extraction, quality appraisal, synthesis).