Table 2. Quality assessment of eligible studies Newcastle-Ottawa Scale (NOS) score.

Author	Country	Selection				Comparability	Outcome			Total
		Adequate of case definition	Representativeness of the cases	Selection of Controls	Definition of Controls	Comparability of cases and controls	Ascertainment of exposure	Same method of ascertainment	Non-Response rate
Xiao XH 2020	China	*	*	*	*	*	*	*	*	8
He XZ 2016	China	*	*	*	*	**	*	*	*	9
Tong LF 2019	China	*	*	*	*	*	-	*	-	6
Chen L 2020	China	*	*	*	*	*	*	*	*	8
Zhao WG 2020	China	*	*	*	*	*	*	*	*	8
Bing ZX 2021	China	*	*	*	*	*	*	*	*	8
Zhang XD 2020	China	*	*	*	*	*	*	*	*	8
Fu Y 2019	China	*	*	*	*	*	*	*	*	8
Yan RC 2019	China	*	*	*	*	*	*	*	*	8
Li M 2019	China	*	*	*	*	**	*	*	*	9
Bai Y 2019	China	*	*	*	*	*	*	-	-	6
Qu CX 2019	China	*	*	*	*	*	*	-	-	6