Characteristics | Category | N | No. (Per cent) | Median (P25–P75) |
Article | ||||
Mention of the use of a guideline other than PRISMA | Moose | 23 | 17 (73.9) | |
Mars | 2 (8.7) | |||
Cochrane | 1 (4.35) | |||
Quorom | 1 (4.35) | |||
Strobe | 1 (4.35) | |||
Centre for reviews and dissemination | 1 (4.35) | |||
Open access | Yes | 206 | 20 (9.7) | |
Protocol registration | Yes | 206 | 15 (7.3) | |
Cochrane MA | Yes | 206 | 1 (0.5) | |
Presence of a search strategy | Yes | 206 | 81 (39.3) | |
Presence of a linguistic bias | Yes | 206 | 96 (46.6) | |
Use of statistical software | Yes | 170 (82.5) | ||
Statistical software used | CMA | 193 | 87 (45.1) | |
STATA | 30 (15.6) | |||
Revman | 29 (15) | |||
SPSS | 17 (8.8) | |||
R | 10 (5.2) | |||
SAS | 4 (2.1) | |||
Other | 17 (8.8) | |||
No. of studies included in the first MA | 1–3 studies | 206 | 11 (5.3) | |
4–9 studies | 57 (27.7) | |||
≥10 studies | 138 (67) | |||
Assessment of the risk of bias (RoB) in individual studies | Yes | 206 | 111 (53.9) | |
Tool used to assess the risk of bias | RoB tool | 95 | 36 (37.9) | |
Newcastle-Ottawa Scale (NOS) | 14 (14.7) | |||
Downs and Black | 6 (6.3) | |||
Jadad | 5 (5.3) | |||
Pedro | 5 (5.3) | |||
Quadas | 5 (5.3) | |||
Other | 24 (25.3) | |||
Design of the included studies | Experimental | 60 (29.1) | ||
Observational | 97 (47.1) | |||
All types | 18 (8.7) | |||
Not specified | 31 (15.1) | |||
Authors | ||||
No. of authors | 1 author | 206 | 12 (5.8) | |
2–3 authors | 60 (29,1) | |||
4–6 authors | 98 (47.6) | |||
≥7 authors | 36 (17.5) | |||
Continent of first author (workplace) | Africa | 206 | 1 (0.5) | |
America | 64 (31.1) | |||
Asia | 41 (19.9) | |||
Europe | 70 (34) | |||
Oceania | 30 (14.5) | |||
Country of first author (workplace) | USA | 206 | 49 (23.8) | |
Australia | 26 (12.6) | |||
China | 22 (10.7) | |||
England | 22 (10.7) | |||
Netherlands | 15 (7.3) | |||
Canada | 13 (6.3) | |||
Germany | 11 (5.3) | |||
Other (<11 reviews/country, 25 countries) | 48 (23.3) | |||
H index of first author | 205 | 5 (2–12) | ||
H index of last author | 195 | 22 (10–35) | ||
Experience with MAs of the first author | Years | 206 | 2 (1–5) | |
Affiliation of the first author | University | 206 | 189 (91.8) | |
Declaration of conflicts of interest | Yes | 206 | 129 (62.6) | |
Management of conflicts of interest | None | 206 | 114 (55.3) | |
Described how they managed | 15 (7.3) | |||
Not indicated | 77 (37.4) | |||
Journal | ||||
Journal impact factor (2016) | 0.0–5.0 | 200 | 148 (71.9) | |
5.1–10.0 | 45 (21.8) | |||
10.1–15.0 | 1 (0.5) | |||
>15.0 | 5 (2.4) | |||
No impact factor | 7 (3.4) | |||
Impact factor | 200 | 3.3 (2.3–5.2) | ||
PRISMA-endorsing journal | Yes | 206 | 61 (29.6) | |
Limitation of words | Yes | 206 | 130 (63.1) | |
Methodological quality | ||||
AMSTAR 2 tool | High quality | 206 | 1 (0.5) | |
Moderate quality | 2 (1) | |||
Low quality | 8 (4) | |||
Critically low quality | 195 (94.5) |
AMSTAR2, A MeaSurement Tool to Assess systematic Reviews; MAs, meta-analyses; PRISMA, Preferred Reporting Items for Systematic Reviews and Meta-Analyses.