Table 3.

Study quality evaluation with Newcastle-Ottawa quality assessment scale.

Case-control studies
Reference	Selection	Comparability	Exposure
Zhenfei Ou 2021	★★	★★	★★★
Nur Aisyah Zainordin 2019	★	★★	★★★
Xiaoqing Mo 2019	★★	★★	★★★
Sachiko Hattori 2018		★★	★★★
Xiaoying Xia 2020	★★	★★	★★★
Daxiang Huang 2020	★★	★★	★★★
Wenjun Zhang 2021	★★	★★	★★★
Nedogoda S.V 2020		★	★★★
Cohort studies
Reference	Selection	Comparability	Outcome
Aki Okamoto 2016	★★	★★	★★★
Ryotaro Bouchi 2017	★	★★	★★★
Hiroshi Tobita 2017	★	★	★★★
Akira Sezai 2019	★★	★	★★★
Takeshi Osonoi 2018	★★	★	★★★