Table 2. Quality of the included studies assessed by Cochrane risk of bias assessment.

Quality assessment criteria	Kaizhong Yao, 2020	Dezhong Cheng, 2020
Random sequence generation(selection bias)	+	+
Allocation concealment(selection bias)	+	+
Blinding participants and personnel(performance bias)	-	-
Blinding of outcome assessment(detection bias)	+	+
Incomplete outcome data(attrition bias)	+	+
Selective reporting(reporting bias)	+	+
Other bias	+	+
Overall quality score (maximum = 7)	6	6