Table 2.
Methodological quality of included trials.
| Study ID | A | B | C | D | E | F | G |
|---|---|---|---|---|---|---|---|
| Gao et al. 2013 [28] | − | − | + | − | + | ? | ? |
|
| |||||||
| Qu 2013 [29] | − | + | + | + | − | ? | ? |
|
| |||||||
| Wu and Li 2012 [30] | − | − | + | + | − | ? | ? |
+ = high risk, ? = unclear, and − = low risk. A = random sequence generation (selection bias); B = allocation concealment (selection bias); C = blinding of participants and personnel (performance bias); D = blinding of outcome assessment (detection bias); E = incomplete outcome data (attrition bias); F = selective reporting (reporting bias); G = other bias.