. 2019 Dec 17;10:1294. doi: 10.3389/fneur.2019.01294

Table 1.

Results of quality assessment of the studies using the Newcastle—Ottawa Assessment Scale (According to, Newcastle Ottawa Quality assessment forms, observational studies can receive a maximum of 10 stars, whereas cohort and case-control studies can be attributed a maximum of 9 stars).

References	Study design	Selection	Comparability	Outcome/ exposure	Total Score
Sokolov et al. (40)	Cohort	^,0,^,^*	^*,0	^*,0,0	5/9
Raj and Gupta (21)	Cross sectional	0,^,0,^*	^,^	^**,0	7/10
Devroede et al. (41)	Cohort	^,^,0,0	^,^	^*,^	7/9
Corwin et al. (42)	Cohort	^,0^,0	^*,0	^,^,^*	6/9
Thierry et al. (24)	Cohort	0,0,^,^	^*,0	^*,0,0	4/9
Wolter et al. (43)	Case control	^,0,^,^*	^*,0	^,^,0	6/9
Akbarfahimi et al. (44)	Case-Control	^,^,^,^	^,^	^,^,^*	9/9
Mucha et al. (45)	Cross sectional	0,^,0,^^*	0,0	^^,0	5/10
Cushing et al. (46)	Cross sectional	^,^,^,^^*	^,^	^^,^*	10/10
Schwab and Kontorinis (47)	Case control	^*,0,0,0	^*,0	^,^,0	4/9
Jafari and Asad Malayeri (48)	Case Control	^,^,^,^	^,^	^,0,^^^	8/9
Zhou et al. (19)	Cohort	0,0,^*,0	^*,0	^*,0,0	3/9
Licameli et al. (13)	Cohort	0,^,^,^*	^,^	^,^,^*	8/9
Jacot et al. (25)	Cohort	^,^,^*,0	^,^	^,^,0	7/9
Cushing et al. (22)	Cross sectional	^,^,^,^^*	^,^	^^,^*	10/10
Shinjo et al. (49)	Cross sectional	0,0,0,^^	^,^	^^,0	6/10
Jin et al. (50)	Cross sectional	^,^,0,^^	^,^	^^,^*	9/10
Bouccara et al. (51)	Cohort	^,0,^,0	^*,0	^,^,0	5/9
Lisboa et al. (15)	Cohort	^,0,^,^*	^*,0	^,^,^*	7/9
Rine et al. (20)	Cross sectional	0,0,0,^^	^*,0	^^,0	5/10
Horak et al. (52)	Case Control	^,^,^*,0	^,^	^0,0,^	7/9
Vartiainen et al. (34)	Cohort	^,0,^,0	^,^	^,^,0	6/9
Potter and Silverman (53)	Case Control	^, 0, 0, ^	^*,0	^*,0,0	4/9
Rosenblüt et al. (54)	Case control	^,0,^,^*	^*,0	^,^,0	6/9