Table 2.

Quality assessment of eligible studies Newcastle–Ottawa scale (NOS) score

Author	Selection	Representativeness of the cases	Selection of Controls	Definition of Controls	Comparability	Outcome	Same method of ascertainment	Non-Response rate	Total
	Adequate of case definition				Comparability of cases and controls	Ascertainment of exposure
Ma ZP 2018	*	*	*	*	*	*	*	*	8
Li YR 2018	*	*	*	*	*	*	*	*	8
Zhang LY 2021	*	*	*	*	*	*	*	–	7
Wang ZW 2018	*	*	*	*	*	*	*	–	7
Liu DT 2020	*	*	*	*	*	*	*	–	7
Wei SS 2021	*	*	*	*	*	*	*	*	8
Xing XJ 2022	*	*	*	*	–	*	*	*	7
Zhao L 2016	*	*	*	*	*	*	*	–	7
Li XY 2021	*	*	*	*	*	*	*	*	8
Ying XY 2019	*	*	*	*	*	*	*	–	7
Kang SY 2023	*	*	*	*	*	*	*	–	7

“*” indicates that the original article meets this entry based on the NOS score, and “_” indicates that the original article does not meet this entry. For example, the article of Zhang LY 2021 miss the The follow-up time, so the module of "non-response rate" of NOS score is also missing, and therefore deducted pointss