Table 2 Risk of bias assessment using Modified Version of Newcastle Ottawa Scale
| Â | Is the source population appropriate and representative of population of interest? | Is the source sample size sufficient and is there sufficient power to detect a meaningful difference in outcome? | Did the study adjust for any variables or confounders that may influence the outcome? | Did the study use appropriate statistical analysis methods relative to the outcome of interest? | Is there little missing data and did the study handle it accordingly? | Is the methodology of the outcome measurement explicitly stated and is it appropriate? Is there an objective assessment of outcome? | Was the follow-up sufficiently long enough for the outcome to occur? | Was there minimal loss to follow-up and are subjects lost to follow-up unlikely to introduce bias? |
|---|---|---|---|---|---|---|---|---|
Barrett & Scott, (1990) [36] | 2 | 0 | 0 | 2 | 3 | 2 | NA | NA |
Bolton et al., (2013) [19] | 2 | 3 | 3 | 2 | 3 | 3 | 2 | 3 |
Cerel et al., (1999) [34] | 2 | 1 | 0 | 2 | 0 | 3 | 3 | 1 |
Cleiren et al., (1994) [37] | 2 | 2 | 0 | 1 | 3 | 1 | 2 | 2 |
Demi and Miles, (1988) [38] | 0 | 2 | 1 | 2 | 3 | 2 | NA | NA |
De Groot et al., (2006) [30] | 2 | 3 | 2 | 3 | 3 | 2 | NA | NA |
Dyregrov et al., (2003) [33] | 3 | 3 | 2 | 3 | 3 | 2 | NA | NA |
Erlangsen et al., (2017) [35] | 3 | 3 | 2 | 3 | 3 | 3 | 3 | 3 |
Fang et al., (2011) [44] | 3 | 3 | 2 | 3 | 3 | 3 | 3 | 3 |
Farberow et al., (1992) [22] | 2 | 3 | 3 | 3 | 3 | 2 | 2 | 1 |
Grad and Zavasnik, (1999) [39] | 3 | 1 | 0 | 2 | 3 | 2 | 2 | 1 |
Harwood et al., (2002) [40] | 2 | 1 | 2 | 2 | 3 | 2 | NA | NA |
Huang et al., (2013) [20] | 2 | 3 | 2 | 3 | 3 | 3 | 3 | 3 |
Kennedy et al., (2014) [45] | 3 | 3 | 2 | 3 | 3 | 3 | 3 | 3 |
Kitson, (2000) [41] | 2 | 2 | 2 | 2 | 3 | 2 | NA | NA |
Miyabashi and Yasuda, (2007) [32] | 0 | 1 | 1 | 2 | 2 | 2 | NA | NA |
Momen et al., (2013) [26] | 3 | 1 | 3 | 3 | 3 | 3 | 3 | 3 |
McNeil et al., (1988) [42] | 2 | 0 | 0 | 2 | 3 | 2 | NA | NA |
Pfeffer et al., (2000) [24] | 1 | 0 | 2 | 2 | 2 | 2 | NA | NA |
Reed and Greenwald, (1991) [43] | 3 | 2 | 2 | 2 | 3 | 1 | NA | NA |
Seguin et al., (1995) [31] | 2 | 1 | 2 | 2 | 3 | 2 | 2 | 1 |
Weinberg et al., (2013) [46] | 1 | 1 | 2 | 3 | 3 | 3 | 3 | 1 |
Wilcox et al., (2015) [47] | 2 | 3 | 2 | 3 | 3 | 2 | 3 | 3 |
Xu and Li, (2014) [23] | 3 | 2 | 3 | 2 | 3 | 2 | NA | NA |