Table 2.
Basic characteristics of studies
| Study | A | B | C | D | E | F | G | H | I | J | Total |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Baek (2015)[20] | ? | + | − | − | − | − | − | + | + | + | 4 |
| Hang (2017)[21] | ? | + | − | − | − | − | − | + | + | + | 4 |
| Jiang (2015)[22] | − | + | − | − | − | − | − | + | + | + | 4 |
| Li (2016)[23] | − | + | − | − | − | − | − | + | + | + | 4 |
| Liu (2021)[24] | ? | + | − | − | − | − | − | − | ? | + | 2 |
| Park (2015)[25] | − | + | − | − | − | − | − | + | + | + | 4 |
| Wang (2015)[27] | ? | + | − | − | − | − | − | + | + | + | 4 |
| Wang (2018)[28] | ? | + | − | − | − | − | − | + | + | + | 4 |
| Xing (2019)[29] | ? | + | − | − | − | − | − | + | + | + | 4 |
| Yokozawa (2000)[31] | − | + | − | − | − | − | − | + | + | + | 4 |
| Yokozawa (2001)[30] | − | + | − | − | − | − | − | + | + | + | 4 |
| Zeng (2019)[26] | ? | + | − | − | − | − | − | + | + | + | 4 |
A=Sequence generation, B=Baseline characteristics, C=Allocation concealment, D=Random housing, E=Blinding of researchers, F=Random result analysis, G=Blinding of result assessor, H=Incomplete result, I=Selective result reporting, J=Other bias, +=Low risk of bias, −=High risk of bias, ?=Unclear risk of bias