Table 2.

Methodological characteristics of eligible studies and quality score.

References	Representativeness of population	Sample size	Non-respondents	Ascertainment of the exposure (risk factor)	Comparability	Assessment of the outcome	Statistical test	Total stars
Bagley et al. (7)	*	*	*	**	*	*	*	8
Park et al. (31)	*	*	*	**	*	*	*	8
Kataoka et al. (32)	*	*	*	**	*	*	*	8
Rogado et al. (33)	*	—	*	**	*	*	*	7
Patil et al. (34)	*	*	*	**	*	*	*	8
Diem et al. (35)	*	—	*	**	*	*	*	7
Shiroyama et al. (36)	*	*	*	**	*	*	*	8
Zer et al. (37)	*	—	*	**	*	*	*	7
Mezquita et al. (38)	*	*	*	**	*	*	*	8
Fukui et al. (39)	*	—	*	**	*	*	*	7
Maymani et al. (40)	*	—	*	**	*	*	*	7
Petrova et al. (41)	*	*	*	**	*	*	*	8
Liu et al. (42)	*	—	*	**	*	*	*	7
Möller et al. (43)	*	—	*	**	*	*	*	7
Hasegawa et al. (44)	*	—	*	**	*	*	*	7
Dusselier et al. (45)	*	—	*	**	*	*	*	7
Russo et al. (46)	*	*	*	**	*	*	*	8

One “*” means one point.