Table 2.
Downs and Black Quality Assessment Checklist evaluations for methodological quality (Downs and Black 1998)
| Study | Reporting | External validity | Internal validity (bias) | Confounding and selection bias | Power | Total |
|---|---|---|---|---|---|---|
| Choi et al [14] 2015 | 10/11 | 3/3 | 6/7 | 4/6 | 1/1 | 24/28 |
| Kadono et al [15] | 8/11 | 3/3 | 5/7 | 2/6 | 0/1 | 18/28 |
| Matsushita et al [16] 2015 | 11/11 | 3/3 | 5/7 | 3/6 | 0/1 | 22/28 |
| Tienza et al [17] 2015 | 10/11 | 3/3 | 5/7 | 3/6 | 0/1 | 21/28 |
| Jeong et al [18] 2014 | 10/11 | 3/3 | 5/7 | 3/6 | 0/1 | 21/28 |
| Lee et al [19] 2014 | 10/11 | 3/3 | 5/7 | 3/6 | 0/1 | 21/28 |
| Jeong et al [20] 2013 | 10/11 | 3/3 | 5/7 | 3/6 | 0/1 | 21/28 |
| Lee et al [21] 2013 | 11/11 | 3/3 | 5/7 | 3/6 | 0/1 | 22/28 |
| Kim et al [22] 2011 | 11/11 | 3/3 | 6/7 | 3/6 | 0/1 | 23/28 |
| Lim et al [23] 2012 | 11/11 | 3/3 | 5/7 | 3/6 | 0/1 | 22/28 |
| Paparel et al [24] 2009 | 11/11 | 3/3 | 5/7 | 3/6 | 0/1 | 22/28 |
| Lee et al [25] 2006 | 10/11 | 3/3 | 5/7 | 3/6 | 0/1 | 21/28 |
| Coakley et al [26] 2002 | 8/11 | 3/3 | 5/7 | 3/6 | 0/1 | 19/28 |