Table 4.

Quality of included studies (N = 55).

Author	Selection				Comparability	Outcome			Total
	S1	S2	S3	S4	C1	O1	O2	O3
Longitudinal studies
Ackroyd-Stolarz et al. 13	1	1	1	0	0	1	0	0	4
Agashivala and Wu 14	1	1	1	1	1	1	0	0	6
Beer et al. 15	1	1	1	0	1	1	1	1	7
Berdot et al. 16	1	1	1	0	1	0	1	1	6
Borenstein et al. 17	1	1	1	0	0	1	1	1	6
Cardwell et al. 63	1	1	1	0	2	1	1	1	8
Chan et al. 41	1	1	1	1	0	1	1	0	6
Chin et al. 42	1	1	1	0	0	1	1	1	6
Chun et al. 20	1	1	1	0	0	1	1	1	6
De Vincentis et al. 34	1	1	1	0	1	1	1	1	7
Delgado et al. 57	1	1	1	0	1	1	1	1	7
Early et al. 21	1	1	1	1	1	1	1	1	8
Fernández et al. 22	1	1	1	1	0	1	1	1	7
Fick et al. 31	1	1	1	0	0	1	0	0	4
Fick et al. 32	1	1	1	0	1	1	0	0	5
Frankenthal et al. 49	1	1	1	0	0	1	1	1	6
García-Gollarte et al. 50	1	1	1	0	0	1	1	1	6
Gosch et al. 59	1	1	1	0	1	1	1	0	6
Hamilton et al. 23	1	1	1	0	0	1	1	0	5
Hill-Taylor et al. 51	1	1	1	0	0	1	1	0	5
Hyttinen et al. 60	1	1	1	0	1	1	0	0	5
Hyttinen et al. 61	1	1	1	1	1	1	1	1	8
Iaboni et al. 44	1	1	1	0	1	0	1	0	5
Ie et al. 24	1	1	1	0	1	1	1	1	7
Kersten et al. 8	1	1	1	0	1	1	1	1	7
Kose et al. 45	1	1	1	0	0	1	1	0	5
Kose et al. 46	1	1	1	1	1	1	1	0	7
Koyama et al. 38	1	1	1	0	1	1	1	0	6
Lu et al. 33	1	1	1	0	1	1	0	0	5
Manias et al. 52	1	1	1	0	0	1	0	0	4
McMahon et al. 25	1	1	1	1	1	1	0	0	6
Moriarty et al. 36	1	1	1	0	1	1	1	1	7
Nagai et al. 53	1	0	1	0	1	1	1	1	6
Nagai et al. 54	1	1	1	1	1	1	1	1	8
Naples et al.39	1	1	1	1	1	1	1	1	8
Narayan and Narayan 26	1	1	1	0	1	1	1	0	6
Ota et al. 27	1	1	1	1	1	1	1	1	8
Pasina et al. 65	1	1	1	0	1	1	1	0	6
Renom-Guiteras et al. 62	1	1	1	0	1	0	1	1	6
Schiek et al. 28	1	1	1	1	0	1	1	1	7
Sengul Aycicek et al. 40	1	1	1	1	1	1	1	0	7
Shibasaki et al. 47	1	1	1	1	1	1	1	0	7
Stockl et al. 29	1	1	1	1	1	1	0	0	6
Tosato et al. 37	1	1	1	0	2	1	1	0	7
Umit et al. 48	1	1	1	0	0	1	1	0	5
Walker et al. 30	1	1	1	1	1	1	1	1	8
Weeks et al. 55	1	1	1	0	1	1	1	0	6
Cross-sectional studies
Anson et al. 66	1	1	1	0	0	1	NA	NA	4