Tab 2.

Critical reading and assessment of methodological quality for cohort studies.

Main author, year and country	Study type	Question validity	Selection of subjects	Evaluation	Confounding factors	Statistic analysis	Overall rating of the study	Study description	Summary assessment
									Medium
Haynos, Et al, 2016, Spain (3, 4)	Cohort	A	A	A	A	A	B	A	Yes
Maezono, Et al, 2019, Japan / Finland (35)	Cohort	D	B	B	A	A	B	B	Yes
Batista, Et al, 2018, Croatia (36)	Cohort	B	A	B	A	A	B	B	Yes

Note. Cohort studies allow a direct determination of relative risk and allow calculation of the interval between exposure or risk factor and overall study disease (12). It was scored according to the validity of the question, selection of subjects, evaluation, confounding factors, statistical analysis, general assessment and description of the study. Rating: according to the author, the items were rated as follows: A: adequately; B: partially; C: improperly; D: I don’t know. For the purposes of this review, it was assumed that studies with adequate rating in 23-26 items were considered to be of high methodological level; medium level was attributed to studies with adequate rating in 19-22 items, and low methodological level was attributed to studies with adequate rating in 18 items or less.