Table 3.

Quality measure of included studies by the Newcastle–Ottawa quality assessment scale

Cohort retrospective studies (12/15)
Study	Selection				Comparability		Outcome			Tot
	1)	2)	3)	4)	a)	b)	1)	2)	3)
Beltran-Corbellini et al. [27]	*	*	*		*	*	*	*		77
Cai et al. [12]	*	*	*		*	*	*	*		7
Chuan Qin et al. [4]	*	*	*		*	*	*	*		7
Duanmu et al. [22]	*	*	*	* *			* *	*		88
Feng et al. [13]	*	*	*		*	*	*	*		7
Jain et al. [24]	*	*	*		*	*	*	*		77
Lechien et al. [15]	*	*	*		*	*	*	*		7
Li K et al. [16]	*	*	*		*	*	*	*		7
Li R et al. [17]	*	*	*		*	*	*	*		7
Mahammedi et al. [25]	*	*	*		*	*	*	*		77
Mao et al. [7]	*	*	*		*	*	*	*		7
Qin et al. [23]	*	*	*		*	*	*	*		7
Radmanesh et al. [26]	*	*	*		*	*	*	*		77
Tian et al. [18]	*	*	*		*	*	*	*		7
Wan et al. [19]	*	*	*		*	*	*	*		7
Wang et al. [20]	*	*	*		*	*	*	*		7
Xu et al. [21]	*	*	*		*	*	*	*		7