| Reporting (0–11) | External validity (0–3) | Internal validity—bias (0–7) | Internal validity—confounding (0–6) | Quality Index score (0–27) (%) |
---|---|---|---|---|---|
de David et al. 2015 [23] | 8 | 1 | 5 | 0 | 14 (52) |
Diop et al. 2005 [24] | 9 | 1 | 5 | 2 | 17 (63) |
Dubbeldam et al. 2010 [25] | 8 | 1 | 5 | 1 | 15 (56) |
Giarmatzis et al. 2015 [26] | 9 | 1 | 5 | 2 | 17 (63) |
Hsiao et al. 2015 [27] | 6 | 1 | 5 | 0 | 12 (44) |
Kerrigan et al. 1998 [28] | 8 | 1 | 5 | 1 | 15 (56) |
Khan et al. 2017 [29] | 7 | 1 | 5 | 2 | 15 (56) |
Kwon et al. 2015 [30] | 6 | 1 | 4 | 1 | 12 (44) |
Lewek 2011 [31] | 8 | 1 | 5 | 1 | 15 (56) |
Linden et al. 2002 [32] | 5 | 1 | 5 | 1 | 12 (44) |
Monaco et al. 2009 [33] | 8 | 2 | 5 | 1 | 16 (59) |
Ridge et al. 2016 [34] | 9 | 1 | 5 | 2 | 17 (63) |
Riley et al. 2001 [35] | 7 | 1 | 5 | 0 | 13 (48) |
Robbins et al. 2009 [36] | 9 | 1 | 5 | 3 | 18 (67) |
Schwartz et al. 2008 [7] | 7 | 1 | 5 | 1 | 14 (52) |
Silder et al. 2008 [37] | 9 | 1 | 5 | 2 | 17 (63) |
Wang et al. 2017 [38] | 6 | 1 | 5 | 0 | 12 (44) |
Weinhandl et al. 2017 [39] | 8 | 1 | 5 | 2 | 16 (59) |
Winiarski et al. 2019 [40] | 9 | 3 | 5 | 1 | 18 (67) |
Yang et al. 2013 [41] | 7 | 1 | 5 | 1 | 14 (52) |
 |  |  |  | Mean | 15 (55) |