Table II.
Risk of bias for each study.
| Risk of bias | |||||||
|---|---|---|---|---|---|---|---|
|
|
|||||||
| Study (ref.) | A | B | C | D | E | F | G |
| Kim et al, 2012 (8) | Low | Unclear | Low | Low | Low | Low | Low |
| Lee et al, 2008 (9) | Unclear | Low | Low | Low | Low | Low | Low |
| Xiong et al, 2013 (15) | Unclear | Unclear | Low | Low | Low | Low | Low |
| Zhang et al, 2010 (17) | Unclear | Unclear | Low | Low | Low | Low | Low |
| Ba et al, 2012 (11) | Unclear | Unclear | Low | Low | Low | Low | Low |
| Yan et al, 2012 (16) | Unclear | Unclear | Low | Low | Low | Low | Low |
| Qiu et al, 2011 (13) | Unclear | Unclear | Low | Low | Low | Low | Low |
| Hong et al, 2012 (7) | Low | Low | Low | Low | Low | Low | Low |
| Sun et al, 2013 (14) | Low | Unclear | Low | Low | Low | Low | Low |
| Lu et al, 2012 (12) | Unclear | Unclear | Low | Low | Low | Low | Low |
| Zang et al, 2012 (10) | Unclear | Unclear | Low | Low | Unclear | Unclear | Unclear |
A, random sequence generation; B, allocation concealment; C, binding of participants and personnel; D, binding of outcome assessment; E, incomplete outcome data; F, selective reporting; G, other bias.