Table 3.

Risk of bias evaluation; A-I represents rating categories according to Newcastle–Ottawa Scale for assessing the quality of non-randomized studies

Study	A	B	C	D	E	F	G	H	I
Gross, 2009	✓	✓	✓	✓	✓	✓	✓	✓	✓
Loftus, 2020	✓	✓	✓	✓	✓	✓	✓	×	✓
Carver, 2018	✓	✓	✓	✓	✓	✓	✓	×	✓
Kataoka, 2016	✓	✓	✓	✓	✓	✓	✓	×	✓
Jang, 2020	✓	×	✓	✓	×	✓	✓	×	✓

A, Representativeness of the exposed cohort; B, Selection of the non-exposed cohort; C, Ascertainment of Exposure; D, Outcome of interest was not present at start of study; E, Comparability of cohorts- major factor controlled for; F, Comparability of cohorts- any additional factor controlled for; G, Assessment of outcome; H, Follow-up duration; I, Follow-up Adequacy