Table 2:
Risk of bias assessment in the included studies
| Study (yr) | Random sequence generation | Allocation concealment | Blinding of participants and personnel | Blinding of out-come assessment | Incomplete outcome data | Selective reporting | Other bias |
|---|---|---|---|---|---|---|---|
| An (2018)(4) | H | U | U | U | L | U | U |
| Du (2015)(5) | H | U | U | U | L | U | U |
| Gu (2015)(6) | H | U | U | U | L | U | U |
| Guan (2013)(7) | L | H | H | H | L | U | L |
| Guo (2017)(8) | H | U | U | U | L | U | U |
| Huang (2012)(9) | H | U | U | U | L | U | U |
| Jin (2015)(10) | U | U | U | U | L | U | U |
| Li (2013)(11) | U | H | H | H | L | U | U |
| Li (2012)(12) | U | H | H | H | L | U | U |
| Li (2012)(13) | U | U | U | U | L | U | U |
| Liu (2009)(14) | U | H | H | H | L | U | U |
| Mao (2017)(15) | L | U | U | U | L | U | L |
| Qiao (2009)(16) | U | H | H | H | L | U | U |
| Ren (2010)(17) | H | H | H | H | L | U | U |
| Shi (2018)(18) | H | U | U | U | L | U | U |
| Sun (2011)(19) | U | H | H | H | L | U | U |
| Tian (2006)(20) | U | H | H | H | L | U | U |
| Wang (2013)(21) | L | H | H | H | L | U | L |
| Wu (2009)(22) | H | H | H | H | L | U | U |
| Wu (2016)(23) | U | U | U | U | L | U | U |
| Zhai (2008)(24) | U | U | U | U | L | U | U |
| Zhao (2016)(25) | U | U | U | U | L | U | U |
| Zhao (2016)(26) | U | U | U | U | L | U | U |
| Zhu (2018)(27) | U | U | U | U | L | U | U |
H, high risk; L, low risk; U, unclear risk.