Table 1. Quality assessment of the 76 reviews with strong, moderate or weak quality.

Quality assessment question	Reviews with strong, moderate or weak quality
	Reviews (N) with ”yes” among the 20 reviews of strong quality	Average across the 20 reviews of strong quality	Reviews (N) with ”yes” among the 32 reviews of moderate quality	Average across the 32 reviews of moderate quality	Reviews (N) with ”yes” among the 24 reviews of weak quality	Average across the 24 reviews of weak quality
1. Are the population, intervention, and outcomes clearly described in the research question or inclusion criteria?	19	0.95	28	0.88	21	0.88
2. Were appropriate inclusion criteria used to select primary studies?	19	0.95	31	0.97	15	0.63
3. Did the authors describe a search strategy that was comprehensive?	10	0.50	12	0.38	6	0.25
4. Did the search strategy cover an adequate number of years?	20	1	31	0.97	20	0.83
5. Did the authors describe the level of evidence in the primary studies included in the review?	20	1	31	0.97	13	0.54
6. Did the review assess the methodological quality of the primary studies?	19	0.95	8	0.25	1	0.04
7. Are the quality of the primary studies assessed by a minimum of two authors and the method of conflict resolution described?	13	0.65	9	0.28	0	0
8. Was it appropriate to combine the findings of results across studies?	20	1	28	0.85	5	0.21
9. Were appropriate methods used for combining or comparing results across studies?	16	0.80	14	0.44	0	0
10. Do the data support the author’s interpretation?	20	1	8	0.25	0	0
Total quality score	176	8.80	200	6.25	82	3.41