Table 3. Risk of bias assessment—modified Newcastle-Ottawa Scale.

Study (first author, publication year)		Selection				Comparability		Outcome				Total NOS Scoring
		Representative of the exposed cohort	Selection of external control	Ascertainment of exposure		Comparability of groups (0= no groups, 1= no matching of subjects, 2= subjects were comparable)		Ascertainment of Assessment (independent or blind, record linkage, self-report, or no description)	Statistical test (0= statistical test, not described or incomplete, 1= statistical test is appropriate and described in a comprehensive manner)	Complete follow-up of all subjects accounted for
Sridhar, 2019†		0	0	1		0		0	0	0		1
Sze-Jung Wu, 2016		1	1	1		2		1	1	0		7
Epstein, 2018		1	1	1		1		1	1	0		6
Sheha, 2019†		0	0	1		0		0	0	0		1
Mehrotra, 2013		1	1	1		1		1	1	0		6
Montour, 2019†		0	0	1		0		0	0	0		1

^†, indicates review articles: limited by study design that lacks comparability or outcomes. NOS, Newcastle-Ottawa Scale.