Table 2.
Risk of bias assessment using Modified Version of Newcastle Ottawa Scale
| 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 |