Introduction
Methods
Eligibility criteria
Literature search
Literature screening and data extraction
Methodological quality assessment
Data analysis
Results
Literature selection
Bibliographical characteristics of the included systematic reviews
Bibliographical characteristics | Results* |
---|---|
Cochrane review | 5 (4.7) |
An update of previous review | 19 (17.9) |
An update of previous Cochrane review | 3 (2.8) |
An update of a previous non-Cochrane review | 16 (15.1) |
Publication journal impact factor median (range) | 2.0 (0–6.8) |
Number of review authors median (range) | 6 (2–13) |
Location of corresponding author | |
Europe | 4 (3.8) |
America | 7 (6.6) |
Asia | 93 (87.7) |
Oceania | 2 (1.9) |
Number of primary studies included in SRs | |
Total | 1864 |
Median (range) | 13.5 (3–73) |
Number of participants enrolled in the primary studies of SRs | |
Total | 204,784 |
Median (range) | 1238 (178–20,827) |
SRs reporting intervention harms | 76 (71.7) |
Funding location of the SR | |
Europe | 4 (3.8) |
America | 4 (3.8) |
Asia | 66 (62.3) |
Not reported | 8 (7.5) |
No funding support | 24 (22.6) |
SRs that searched English databases | 105 (99.1) |
SRs that searched non-English databases | 88 (83.0) |
Report year span of search | |
Yes, reported both starting and ending years | 81 (76.4) |
Partially, only reported starting years | 19 (17.9) |
Not mentioned | 6 (5.7) |
Search terms reported for one or more electronic databases | |
Topics/free text/keywords/MeSH | 47 (44.3) |
Full Boolean | 54 (50.9) |
Readers are referred elsewhere for full search strategy | 0 (0) |
No research term | 5 (4.7) |
Language of included primary studies in SRs | |
English only | 9 (8.5) |
Language other than English | 6 (5.7) |
English and other languages | 32 (30.2) |
Not reported | 59 (55.7) |
Risk of bias assessment tools | |
Cochrane risk of bias | 99 (93.4) |
Jadad scale | 2 (1.9) |
Pedro Scale | 2 (1.9) |
Others | 1 (0.9) |
Risk of bias assessment tool not used | 2 (1.9) |
Included a PRISMA-like flow diagram | 102 (96.2) |
Methodological quality
AMSTAR 2 items | Yes (%) | Partial Yes (%) | No (%) |
---|---|---|---|
1. Did the research questions and inclusion criteria for the review include the components of PICO? | 106 (100) | NA | 0 (0) |
2. Did the report of the review contain an explicit statement that the review methods were established prior to the conduct of the review and did the report justify any significant deviations from the protocol?a | 10 (9.4) | 32 (30.2) | 64 (60.4) |
3. Did the review authors explain their selection of the study designs for inclusion in the review? | 4 (3.8) | NA | 102 (96.2) |
4. Did the review authors use a comprehensive literature search strategy?a | 4 (3.8) | 99 (93.4) | 3 (2.8) |
5. Did the review authors perform study selection in duplicate? | 94 (88.7) | NA | 12 (11.3) |
6. Did the review authors perform data extraction in duplicate? | 97 (91.5) | NA | 9 (8.5) |
7. Did the review authors provide a list of excluded studies and justify the exclusions?a | 5 (4.7) | 1 (0.9) | 100 (94.3) |
8. Did the review authors describe the included studies in adequate detail? | 12 (11.3) | 84 (79.2) | 10 (9.4) |
9. Did the review authors use a satisfactory technique for assessing the risk of bias (RoB) in individual studies that were included in the review?a | 97 (91.5) | 3 (2.8) | 6 (5.7) |
10. Did the review authors report on the sources of funding for the studies included in the review? | 4 (3.8) | NA | 102 (96.2) |
11. If meta-analysis was performed, did the review authors use appropriate methods for statistical combination of results?a | 6 (5.7) | NA | 100 (94.3) |
12. If meta-analysis was performed, did the review authors assess the potential impact of RoB in individual studies on the results of the meta-analysis or other evidence synthesis? | 19 (17.9) | NA | 87 (82.1) |
13. Did the review authors account for RoB in individual studies when interpreting / discussing the results of the review?a | 78 (73.6) | NA | 28 (26.4) |
14. Did the review authors provide a satisfactory explanation for, and discussion of, any heterogeneity observed in the results of the review? | 84 (79.2) | NA | 22 (20.8) |
15. 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?a | 23 (21.7) | NA | 83 (78.3) |
16. Did the review authors report any potential sources of conflict of interest, including any funding they received for conducting the review? | 104 (98.1) | NA | 2 (1.9) |
Relationship between bibliographical characteristics and overall methodological quality
Bibliographical characteristics | Critically low^ | Low^ | Moderate^ | High^ | P |
---|---|---|---|---|---|
Total included SRs | 99 (93.4) | 6 (5.7) | 0 (0.0) | 1 (0.9) | |
Cochrane Review | < 0.001* | ||||
Yes | 0 (0.0) | 4 (80.0) | 0 (0.0) | 1 (20.0) | |
No | 99 (98.0) | 2 (2.0) | 0 (0.0) | 0 (0) | |
An update of a previous review | 0.007* | ||||
Yes (Cochrane review) | 3 (100) | 0 (0) | 0 (0.0) | 0 (0.0) | |
Yes (non-Cochrane review) | 12 (75.0) | 3 (18.8) | 0 (0.0) | 1 (6.3) | |
No | 84 (96.6) | 3 (3.4) | 0 (0.0) | 0 (0.0) | |
Reported intervention harms | 0.659 | ||||
Yes | 70 (92.1) | 5 (6.6) | 0 (0.0) | 1 (1.3) | |
No | 29 (96.7) | 1 (3.3) | 0 (0.0) | 0 (0.0) | |
Funding location of the SR | 0.859 | ||||
Europe | 4 (100.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | |
America | 4 (100.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | |
Asia | 61 (92.4) | 4 (6.1) | 0 (0.0) | 1 (1.5) | |
Not reported | 7 (87.5) | 1 (12.5) | 0 (0.0) | 0 (0.0) | |
No funding support | 23 (95.8) | 1 (4.2) | 0 (0.0) | 0 (0.0) | |
SRs that searched non-English databases | 0.048* | ||||
Yes | 82 (93.2) | 6 (6.8) | 0 (0.0) | 0 (0.0) | |
No | 17 (94.4) | 0 (0.0) | 0 (0.0) | 1 (5.6) | |
Report year of coverage of literature search | 0.323 | ||||
Yes | 74 (91.4) | 6 (7.4) | 0 (0.0) | 1 (1.2) | |
Partially | 19 (100.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | |
Not mentioned | 6 (100.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | |
Search terms reported for one or more electronic databases | 0.287 | ||||
Topics/free text/keywords/MeSH | 47 (100.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | |
Full Boolean | 48 (88.9) | 5 (9.3) | 0 (0.0) | 1 (1.9) | |
Readers are referred elsewhere for full search strategy | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | |
No research term | 4 (80.0) | 1 (20.0) | 0 (0.0) | 0 (0.0) | |
Eligibility criteria based on language of publication | 0.467 | ||||
English only | 9 (100.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | |
Language other than English | 5 (83.3) | 1 (16.7) | 0 (0.0) | 0 (0.0) | |
English and other languages | 28 (87.5) | 3 (9.4) | 0 (0.0) | 1 (3.1) | |
Not reported | 57 (96.6) | 2 (3.4) | 0 (0.0) | 0 (0.0) | |
Risk-of-bias assessment tools | 0.769 | ||||
Cochrane risk of bias | 92 (92.9) | 6 (6.1) | 0 (0.0) | 1 (1.0) | |
Jadad scale | 2 (100.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | |
Pedro Scale | 2 (100.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | |
Others | 1 (100.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | |
Not mentioned | 2 (100.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | |
Included a PRISMA-like flow diagram | 0.865 | ||||
Yes | 95 (93.1) | 6 (5.9) | 0 (0.0) | 1 (1.0) | |
No | 4 (100.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) |