Table 7. Newcastle-Ottawa Quality Assessment Scale for Cohort Studies.

0 - 0 star, 1 - 1 star, and 2 - 2 stars according to Newcastle-Ottawa Scale.

Articles	Representativeness	Selection	Ascertainment	Demonstration that outcome of interest was not present at start of study	Comparability of cohorts	Assessment of outcome	Long follow-up	Adequacy of follow-up	Total score
Widerstrom et al [67]	1	1	0	1	0	1	1	1	6
Alhumaid et al. [68]	1	1	1	1	1	0	1	1	7
Zaha et al. [69]	1	1	0	1	1	1	0	0	5
Cantón et al. [70]	1	1	1	1	1	0	1	0	6
Puzniak et al. [71]	1	1	0	1	1	1	1	1	7
Wu et al. [72]	1	1	0	1	1	0	1	1	6
Mehl et al. [73]	1	0	1	1	0	1	1	1	6
Bai et al. [74]	1	1	1	1	1	1	1	0	7
Stagliano et al. [75]	1	1	1	0	1	1	1	1	7
Álvarez-Marín et al. [76]	1	1	0	1	0	1	1	1	6