Table 1.

Methodological quality of included studies

	Study	Selection bias	Study design	Confounders	Blinding	Data collection	Withdrawals	Global rating
1	Awofeso et al, 200143	Weak	Weak	Weak	Weak	Weak	Strong	Weak
2	Clarke et al, 201344	Strong	Strong	Strong	Moderate	Strong	Strong	Strong
3	Cropsey and Kristeller, 200531	Moderate	Moderate	Weak	NA	Strong	Moderate	Moderate
4	Cropsey et al, 200830	Moderate	Strong	Strong	Weak	Strong	Moderate	Moderate
5	Etter et al, 201245	Weak	Weak	Weak	NA	Weak	Weak	Weak
6	Howell et al, 201532	Weak	Moderate	Weak	NA	Moderate	NA	Weak
7	Jalali et al, 201533	Moderate	Strong	Moderate	Strong	Strong	Strong	Strong
8	Kauffman et al, 201134	Moderate	Moderate	Weak	NA	Strong	NA	Moderate
9	Lasnier et al, 201146	Weak	Weak	Weak	NA	Weak	NA	Weak
10	Leone and Kinkade, 199447	Weak	Weak	Weak	NA	Moderate	NA	Weak
11	Lincoln et al, 200942	Weak	Moderate	Weak	NA	Moderate	Weak	Weak
12	MacAskill et al, 200835	Weak	Weak	Weak	NA	Moderate	Strong	Weak
13	Makris et al, 201236	Weak	Weak	Weak	NA	Moderate	Strong	Weak
14	Naik et al, 201437	Moderate	Strong	Moderate	Weak	Strong	Strong	Moderate
15	Richmond et al, 20068	Strong	Moderate	Weak	Weak	Strong	Strong	Weak
16	Richmond et al, 201338	Strong	Strong	Strong	Strong	Strong	Strong	Strong
17	Thibodeau et al, 201039	Moderate	Moderate	Weak	NA	Strong	Strong	Moderate
18	Turan and Turan, 201648	Strong	Weak	Weak	NA	Weak	Weak	Weak
19	Turner et al, 201340	Moderate	Weak	Moderate	NA	Weak	NA	Weak
20	Voglewede and Noel, 200441	Weak	Weak	Weak	NA	Strong	NA	Weak

NA, not applicable.