Table 6.

Results of the quality assessment of included articles (a: low risk of bias, b: uncertain risk of bias, b: high risk of bias).

Quality assessment criteria	Al-Sibaie et al.(22)	Benson et al.(23)	Feldmann et al.(24)	Liu et al.(25)	Ma et al.(26)	Upadhyay et al.(27)
Random sequence generation (selection bias)	+a	+a	+a	+a	+a	+a
Allocation concealment (Selection bias)	+a	+a	?b	?b	?b	?b
Blinding of outcome assessment (detection bias)	+a	+a	-c	?b	+a	?b
Incomplete outcome data (attrition bias)	+a	+a	+a	+a	+a	+a
Selective reporting (reporting bias)	+a	+a	?b	?b	-c	?b
Other bias	+a	+a	-c	+a	+a	+a