Details of quality assessment of included randomised clinical trials(RCTs)
| First author [ref.] | Double blinded | Appropriate method for blinding | Appropriate method for randomisation | Details of dropouts and withdrawals described | Placebo controlled |
| Cheng 18 | N | NA | NR | NR | N |
| Chen 19 | N | NA | NR | NR | N |
| Meyer-Wegener 17 | Y | NR | NR | Y | N |
| Wei 12 | N | NA | NR | NR | N |
| Xu 20 | N | NA | NR | NR | N |
| Gulyas 21 | Y | NR | NR | Y | N |
| Zhao 13 | N | NA | NR | NR | N |
| Fang 14 | N | NA | NR | NR | N |
| Gross 9 | Y | Y | Y | Y | Y |
| Hauke 15 | Y | NR | NR | Y | Y |
| Mao 22 | Y | NR | NR | NR | N |
| Liu 23 | N | NA | NR | NR | N |
| Wu 24 | N | NA | Y | Y | N |
| Huang 17 | N | NA | Y | NR | N |
| RCTs with each design feature n | 5 | 1 | 3 | 5 | 2 |
N: no; NA: not applicable; NR: not reported; Y: yes.