. 2018 Aug 8;2018:5670949. doi: 10.1155/2018/5670949

Table 2.

Quality assessment and risk of bias of the included trials.

Study	Selection				Comparability	Exposure			Score
Study	1	2	3	4	5	6	7	8	Score
He and Lin	^∗	^∗			^∗	^∗	^∗	^∗	6
Yang et al.	^∗	^∗			^∗	^∗	^∗	^∗	6
Liu et al.	^∗	^∗				^∗	^∗	^∗	5
Casadei et al.	^∗	^∗			^∗	^∗	^∗	^∗	6
Xue et al.	^∗	^∗			^∗	^∗	^∗	^∗	6
Shiozawa et al.	^∗	^∗			^∗	^∗	^∗	^∗	6
Chan et al.	^∗	^∗			^∗	^∗	^∗	^∗	6
Xue et al.	^∗	^∗			^∗	^∗	^∗	^∗	6
Ni et al.	^∗	^∗			^∗	^∗	^∗	^∗	6

^∗The score of each item.