Table 2. Risk of bias assessment.

The first author	Selection bias	Performance bias	Measurement bias	Attrition bias	Reporting bias	Other potential sources of bias	Risk of bias
Mraz-Gernhard S [50]	High	High	Low	Low	Low	Low	High
Kuo TT [51]	Low	Low	Low	Low	Low	Low	Low
Takashashi E [52]	High	Low	Low	Low	Low	Low	High
Pongpruttipan T [53]	Low	Low	Low	Low	Low	Low	Low
Hong J [7]	Low	Low	High	Low	Low	Low	High
Kim WY [6]	Low	Low	Low	Low	Low	Low	Low
Fang JC [54]	Low	High	Low	Low	Low	Low	High
Yu BH [55]	Low	Low	Low	Low	Low	Low	Low
Kim SH [56]	Low	Low	Low	High	Low	Unclear	High
Hu LM [57]	High	High	Low	Low	Low	Low	High