TABLE 2.

The quality assessment of 31 included studies based on the Newcastle–Ottawa Scale (range 0–9).

References	Representativeness of the exposed cohort	Selection of the non-exposed cohort	Ascertainment of exposure	Demonstration that outcome of interest was not present at start of study	Comparability of cohorts on the basis of the design or analysis	Assessment of outcome	Was follow-up long enough for outcomes to occur	Adequacy of follow up of cohorts	Quality score
Abuabara et al. (20)	★	★	★	★	★	★	★	/	7
Ahlehoff et al. (4)	★	★	★	★	★★	★	★	/	8
Ahlehoff et al. (43)	★	★	★	★	★★	★	★	/	8
Ahlehoff et al. (42)	★	★	★	★	★★	★	★	/	8
Ahlehoff et al. (41)	★	★	★	★	★★	★	★	/	8
Brauchli et al. (37)	★	★	★	★	★★	★	★	/	8
Chiang et al. (21)	★	★	★	★	★★	★	★	/	8
Chiu et al. (22)	★	★	★	/	★★	★	★	★	8
Chiu et al. (23)	★	★	★	★	★★	★	★	/	8
Chung et al. (24)	★	★	★	★	★★	★	★	/	8
Dregan et al. (44)	★	★	★	★	★★	★	★	★	9
Egeberg et al. (45)	★	★	★	★	★★	★	★	/	8
Egeberg et al. (25)	★	★	★	★	★★	★	★	/	8
Gelfand et al. (39)	★	★	★	★	★★	★	★	/	8
Gelfand et al. (38)	★	★	★	★	★★	★	★	/	8
Jung et al. (26)	★	★	★	/	★★	★	★	★	8
Kaye et al. (40)	★	★	★	★	★★	★	★	/	8
Khalid et al. (27)	★	★	★	★	★★	★	★	/	8
Khalid et al. (46)	★	★	★	★	★★	★	★	/	8
Khalid et al. (47)	★	★	★	★	★★	★	★	/	8
Leisner et al. (28)	★	★	★	★	★	★	★	★	8
Levesque et al. (29)	★	★	★	/	★★	★	★	/	7
Lin et al. (30)	★	★	★	★	★★	★	★	/	7
Lin et al. (31)	★	★	★	★	★	★	★	/	7
Mehta et al. (12)	★	★	★	★	★★	★	★	★	9
Mehta et al. (32)	★	★	★	/	★★	★	★	★	8
Ogdie et al. (33)	★	★	★	★	★★	★	★	/	8
Parisi et al. (34)	★	★	★	/	★★	★	★	★	8
Rhee et al. (35)	★	★	★	★	★★	★	★	/	8
Wakkee et al. (36)	★	★	★	★	★★	★	★	/	8
Wu et al. (13)	★	★	★	★	★★	★	★	/	8