Table 2.
Risk of bias.
| The Cochrane Collaboration: Tool for Randomized Studies | ||||||
| Studies | Random sequence generation | Allocation concealment | Blinding of participants and personnel | Blinding of outcome assessment | Incomplete outcome data | Selective reporting |
| Wong, 2014 | Low | Unclear | Low | Low | Low | Low |
| Shinno, 2017 | Unclear | Unclear | Low | Low | Unclear | Unclear |
| Wong, 2017 | Low | Unclear | Low | Low | Low | Low |
| Boonpin, 2017 | Unclear | Unclear | Low | Low | Unclear | Unclear |
| Kato, 2017 | Low | Unclear | Low | Low | Low | Unclear |
| Hotta, 2019 | Unclear | Unclear | Low | Low | Low | Unclear |
| The Risk of Bias Assessment Tool for Non-randomized Studies (RoBANS) | ||||||
| Studies | Selection of participants | Confounding variables | Measurement of exposure | Blinding of outcome assessment | Incomplete outcome data | Selective outcome reporting |
| Nishiwaki, 2015 | Low | Low | Low | Low | Low | Unclear |
| Kim, 2019 |
Low | Unclear | Low | Low | Low | Unclear |
Low, low risk; High, high risk.