Table 2.

The quality assessment of the included studies.

References	Representativeness of exposed cohort	Selection of non-exposed cohort	Ascertainment of exposure	Outcome not present before study	Comparability	Assessment of outcome	Follow-up long enough¶	Adequacy of follow up	Quality score
Zhang et al. (20)	⋆	⋆	⋆	⋆	⋆⋆	⋆	⋆	⋆	9
Lai et al. (21)	⋆	⋆	⋆	⋆	⋆⋆	⋆	⋆	⋆	9
Zhao et al. (22)	⋆	⋆	⋆	⋆	⋆⋆	⋆		⋆	8
Lee et al. (23)	⋆	⋆	⋆	⋆	⋆⋆	⋆	⋆	⋆	9
Li et al. (24)	⋆	⋆	⋆	⋆	⋆⋆	⋆		⋆	8
Maegawa et al. (25)	⋆	⋆	⋆	⋆	⋆⋆	⋆		⋆	8
Sonohara et al. (26)	⋆	⋆	⋆	⋆	⋆⋆	⋆		⋆	8
Yang et al. (27)	⋆	⋆	⋆	⋆	⋆⋆	⋆		⋆	8
Matsumoto et al. (28)	⋆	⋆	⋆	⋆	⋆⋆	⋆	⋆	⋆	9
Sarkar et al. (29)	⋆	⋆	⋆	⋆	⋆	⋆		⋆	7
Allenson et al. (30)	⋆	⋆	⋆	⋆	⋆⋆	⋆			7
Ji et al. (31)	⋆	⋆	⋆	⋆	⋆⋆	⋆		⋆	8
Zhu et al. (32)	⋆	⋆	⋆	⋆	⋆⋆	⋆		⋆	8
Tang et al. (33)	⋆	⋆	⋆	⋆	⋆	⋆		⋆	7
Chen et al. (34)	⋆	⋆	⋆	⋆	⋆	⋆		⋆	7
Jaruvongvanich et al. (35)	⋆	⋆	⋆	⋆	⋆⋆	⋆		⋆	8
Shen et al. (36)	⋆	⋆	⋆	⋆	⋆⋆	⋆		⋆	8
Hung et al. (37)	⋆	⋆	⋆	⋆	⋆	⋆	⋆	⋆	8
Toyoda et al. (38)	⋆	⋆	⋆	⋆	⋆	⋆	⋆	⋆	8
Choi et al. (39)	⋆	⋆	⋆	⋆	⋆	⋆		⋆	7
Okamura et al. (40)	⋆	⋆	⋆	⋆	⋆	⋆	⋆	⋆	8
Chung et al. (41)	⋆	⋆	⋆	⋆	⋆⋆	⋆		⋆	8
Kao et al. (42)	⋆	⋆	⋆	⋆	⋆⋆	⋆		⋆	8
Huang et al. (43)	⋆	⋆	⋆	⋆	⋆⋆	⋆		⋆	8
Pang et al. (44)	⋆	⋆	⋆	⋆	⋆⋆	⋆		⋆	8
Liu et al. (45)	⋆	⋆	⋆	⋆	⋆⋆	⋆		⋆	8
Peng et al. (46)	⋆	⋆	⋆	⋆	⋆⋆	⋆		⋆	8
Teng et al. (47)	⋆	⋆	⋆	⋆	⋆⋆	⋆		⋆	8

^¶The median/mean follow-up time ≥60 months or the longest follow-up time ≥120 months is acceptable.