We evaluated the methodological quality of the included studies by applying an 11-item quality checklist, derived from the STREGA and STROBE checklists 62, 63. We extracted information relevant to methodological quality criteria (items 2–7, 10), and basic reporting standards (items 1, 8, 9, 11) from the Introduction, Methods, Results and Discussion sections of all included studies. Consistent with current guidelines, we did not weigh studies by quality scores or exclude studies with low quality studies 64. Instead we report the quality data extracted, so that it is available for readers to evaluate (Supplemental Table 1) 64, 65. Further, to assess whether our results were influenced by studies rated as lower quality through this measure, we repeated our overall meta-analysis with only studies with a quality score above the median 66.
