Table II.
Bias risk assessment of the included studies.
| Author, year | Randomization | Concealed allocation | Researcher blinding | Outcome evaluator blinding | Selective reporting | Other biases | (Refs.) |
|---|---|---|---|---|---|---|---|
| Yang et al, 2016 | Not described | Not clear | Not clear | Not clear | Not clear | Not clear | (31) |
| Cui et al, 2007 | Not described | Not clear | Not clear | Not clear | Not clear | Not clear | (32) |
| Huang et al, 2012 | Random number table method | Not clear | Not clear | Not clear | Not clear | Not clear | (33) |
| Wang et al, 2014 | Not described | Not clear | Not clear | Not clear | Not clear | Not clear | (34) |
| Wang et al, 2009 | Not described | Not clear | Not clear | Not clear | Not clear | Not clear | (35) |
| Zeng et al, 2016 | Not described | Not clear | Not clear | Not clear | Not clear | Not clear | (36) |