Table 2.
The quality assessment of included studies based on the Hayden et al. checklists.
| First author and the year of publication | Study participation | Study attrition | Prognostic factor measurement | Outcome measurement | Confounding measurement and account | Analysis |
|---|---|---|---|---|---|---|
| Tetsu Yamaki, 2020 (17) | *** | *** | *** | *** | *** | *** |
| Yasuo Iwadate, 2017 (15) | *** | *** | *** | *** | *** | *** |
| Yasuo Iwadate, 2016 (14) | *** | *** | *** | *** | *** | *** |
| Ichiyo Shibahara, 2015 (16) | *** | *** | ** | *** | *** | *** |
| Rikke H Dahlrot, 2014 (22) | *** | *** | *** | *** | * | ** |
| Jung Ha Shin, 2013 (23) | *** | *** | *** | *** | *** | *** |
| Ichiyo Shibahara, 2013 (19) | *** | *** | *** | *** | *** | *** |
| Consolación Melguizo 2012 (24) | *** | *** | *** | *** | * | ** |
| Kyung-Jung Kim, 2011 (25) | *** | *** | *** | *** | *** | *** |
| JIE HE, 2011 (26) | *** | *** | *** | * | * | *** |
| Roberto Pallini, 2008 (27) | *** | *** | *** | *** | *** | *** |
| Felix Zeppernick, 2008 (28) | *** | ** | *** | *** | *** | *** |
***Bias might not present; **Bias might be partly present; *Bias might be present.