Table 2.

Assessment of the quality of included studies according to the Newcastle-Ottawa quality assessment scale for non-RCTs.

STUDY	Representativeness of Cohort	Selection of the Non-Exposed Cohort	Ascertainment of Exposure	Outcome of Interest	Comparability of Cohorts	Assessment of Outcome	Adequate Duration of Follow-Up	Adequate Follow-up of Cohort
GENERAL
Patil, et al., 2018	*	-	*	*	-	*	*	*
Song et al. 2021	*	-	*	*	-	*	*	*
Yoon et al., 2012	*	-	*	*	-	*	*	*
Yang et al., 2021	*	-	*	*	-	*	*	*
Porto et al. 2021	*	*	*	*	-	*	*	*
Liu et al., 2021	*	-	*	*	-	*	*	*
Yu et al., 2021	*	-	*	*	*	*	*	*
Ren et al., 2020	*	-	*	*	*	*	*	*
Liu et al., 2018	*	-	*	*	-	*	*	*
Li et al. 2015	*	*	*	*	*	*	*	*
Kunert et al., 2010	*	-	*	*	-	*	*	*
Ranjan et al., 2006	*	-	*	*	*	*	*	*
LOCAL ± EPIDURAL
Abudurexiti et al., 2018	*	-	*	*	-	*	*	*
Song et al., 2017	*	*	*	*	*	*	*	*
Jing et al., 2021	*	*	*	*	*	*	*	*
Pang et al., 2020	*	-	*	*	-	*	*	*
Liu et al., 2010	*	*	*	*	*	*	*	*
Zhou et al., 2009	*	-	*	*	-	*	*	*
Wu et al., 2006	*	*	*	*	*	*	*	*