Table 2.
Quality of each included study.
| References | Study participation | Study attrition | Prognostic factor measurement | Outcome measurement | Study confounding | Statistical analysis and reporting |
|---|---|---|---|---|---|---|
| Kamo et al. (24) |  |
n/a | |
|
X | ? |
| Montano-Loza et al. (20) | |
n/a | |
X | X | ? |
| Itoh et al. (23) | |
n/a | X | |
X | ? |
| Carias et al. (28) | |
n/a | |
|
X | ? |
Green ticks, red crosses, and yellow question marks represent a low, high, and unknown risk of bias, respectively. n/a: not applicable. Details of assessment are presented in Supplementary Appendix 1.