Table 2 Quality assessment of included SRMAs using AMSTAR 2

1

NC

Did the research questions and inclusion criteria for the review include the components of PICO?

Y

Y

Y

Y

Y

Y

2

C

Contain an explicit statement that the review methods were established prior to the conduct of the review and justify any significant deviations from the protocol

N

Y

Y

Y

Y

Y

3

NC

Did the review authors explain their selection of the study designs for inclusion in the review?

Y

Y

Y

Y

Y

Y

4

C

Did the review authors use a comprehensive literature search strategy?

Y

Y

Y

Y

Y

Y

5

NC

Did the review authors perform study selection in duplicate?

Y

Y

Y

Y

Y

Y

6

NC

Did the review authors perform data extraction in duplicate?

Y

Y

Y

Y

Y

Y

7

C

Did the review authors provide a list of excluded studies and justify the exclusions?

Y

Y

N

N

N

Y

8

NC

Did the review authors describe the included studies in adequate detail?

Y

Y

Y

Y

Y

Y

9

C

Did the review authors use a satisfactory technique for assessing the risk of bias in individual studies that were included in the review?

Y

Y

Y

Y

Y

Y

10

NC

Did the review authors report on the sources of funding for the studies included in the review?

N

N

Y

N

N

N

11

C

If meta-analysis was performed did the review authors use appropriate methods for statistical combination of results?

Y

No meta-analysis conducted

No meta-analysis conducted

Y

Y

Y

12

NC

If meta-analysis was performed, did the review authors assess the potential impact of risk of bias in individual studies on the results of the meta-analysis or other evidence synthesis

Y

No meta-analysis conducted

No meta-analysis conducted

Y

Y

Y

13

C

Did the review authors account for risk of bias in individual studies when interpreting/ discussing the results of the review?

Y

No meta-analysis conducted

No meta-analysis conducted

Y

Y

Y

14

NC

Did the review authors provide a satisfactory explanation for, and discussion of, any heterogeneity observed in the results of the review?

Y

Y

N

Y

Y

N

15

C

If they performed quantitative synthesis did the review authors carry out an adequate investigation of publication bias (small study bias) and discuss its likely impact on the results of the review?

Y

N

N

N

Y

N

16

NC

Did the review authors report any potential sources of conflict of interest, including any funding they received for conducting the review?

Y

Y

Y

Y

Y

Y

Overall assessment

Low

Low

Critically low

Low

Low

Critically low