Table 4.

Summary of risk of bias assessment for observational studies using the Newcastle–Ottawa Scale (NOS).

Study ID	Selection (max 4 stars)	Comparability (max 1 star)	Outcome (max 3 stars)	Total Score (max 8)
Franek et al. (2015)	★★★★		★★	6
Wissenberg et al. (2013)	★★★★		★★	6
Dahan et al. (2014)	★		★★	3
Ristagno et al. (2014)	★★★		★	4
Iwami et al. (2015)	★★★★	★	★★★	8
Lai et al. (2015)	★★★		★★	5
Ho et al. (2020)	★★★★	★	★★	7
Ro et al. (2019)	★★★★	★	★★	7
Hollenberg et al. (2008)	★★★★	★	★★	7
Mauri et al. (2010)	★		★★	3
Lin et al. (2016)	★★		★★	4
Lick et al. (2011)	★★★★	★	★★★	8
Bergamo et al. (2016)	★★★★	★	★★★	8
van Diepen et al. (2017)	★★★★	★	★★	7
Uber et al. (2018)	★★★★	★	★★★	8
Del Rios et al. (2019)	★★★★	★	★★★	8