Table 2.

Quality appraisal of the included studies using Newcastle Ottawa Scale (NOS).

Study	Selection				Comparability	Outcome		Total score	Quality
	Representativeness of the sample	Sample size	Non - respondents	Ascertainment of exposure	Based on design and analysis	Assessment of outcome	Statistical test
Chi et al., 2020b	∗	∗		∗∗	∗	∗		6	Satisfactory
Fu et al., 2020	∗	∗		∗∗	∗	∗	∗	7	Good
Guan et al., 2021		∗		∗∗	∗	∗	∗	6	Satisfactory
Jia et al., 2021		∗		∗∗	∗	∗	∗	6	Satisfactory
Jing et al., 2021		∗		∗∗	∗	∗	∗	6	Satisfactory
Li (Xueguo) et al., 2020	∗	∗		∗∗	∗	∗	∗	7	Good
Li (Mengyao) et al., 2020				∗∗	∗	∗	∗	5	Satisfactory
Li (Xueyan) et al., 2021	∗	∗		∗∗	∗	∗		6	Satisfactory
Ma et al., 2020	∗	∗		∗∗	∗	∗	∗	7	Good
Meng et al., 2021				∗∗	∗	∗	∗	5	Satisfactory
Ren et al., 2021		∗		∗∗	∗	∗		5	Satisfactory
Song et al., 2021		∗		∗∗	∗	∗		5	Satisfactory
Sun et al., 2021a		∗		∗∗		∗	∗	5	Satisfactory
Tang et al., 2020	∗	∗		∗∗	∗	∗	∗	7	Good
Wang (Dongfang) et al., 2021	∗	∗		∗∗	∗	∗	∗	7	Good
Wang (Xing) et al., 2020		∗		∗∗	∗	∗		5	Satisfactory
Wang (Zheng-He) et al., 2020		∗		∗∗	∗	∗	∗	6	Satisfactory
Wu et al., 2021	∗	∗		∗∗	∗	∗	∗	7	Good
Xiang et al., 2020		∗		∗∗	∗	∗		5	Satisfactory
Xiong et al., 2021		∗		∗∗	∗	∗		5	Satisfactory
Xu et al., 2021	∗	∗		∗∗	∗	∗	∗	7	Good
Yang et al., 2021		∗		∗∗	∗	∗	∗	6	Satisfactory
Yu (Chang) et al., 2021		∗		∗∗	∗	∗		5	Satisfactory
Yu (Mingli) et al., 2021		∗		∗∗	∗	∗	∗	6	Satisfactory
Yu (Jincong) et al., 2021	∗	∗		∗∗	∗	∗	∗	7	Good
Yu (Yanqiu) et al., 2021	∗	∗		∗∗	∗	∗		6	Satisfactory
Zhang (Xudong) et al., 2021		∗		∗∗	∗	∗	∗	6	Satisfactory
Zheng et al., 2021	∗	∗		∗∗		∗	∗	6	Satisfactory
Zhou et al., 2020	∗		∗	∗∗	∗	∗	∗	7	Good
Zhang (Yifan) et al., 2021	∗	∗		∗∗	∗	∗	∗	7	Good