Table 2.

Quality assessment of studies included in this systematic review according to the Newcastle Ottawa scale for Cohort, Case-Control and Cross Sectional Studies^a

Cohort studies	Representativeness of the exposed cohort	Sample Size	Response Rate	Ascertainment of Exposure	Study Controls for Relevant Confounders (Age, SES, Health)	Study Controls for Additional Factors (i.e. Stress)	Assessment of outcome	Was follow-up long enough for outcomes to occur (> 9 months)	Adequacy of follow up of cohorts (loss-to-follow-up < 20%)	Total score
Barha et al. 2018 [57]	-	*	-	*	*	-	*	*	*	6
Mitchel et al. 2018 [67]	*	*	-	**	*	*	*	*	-	8
Panelli et al. 2022 [69]	*	-	-	**	-	-	*	*	*	6
Saberi et al. 2019 [68]	-	*	*	**	-	-	*	*	*	7
Zota et al. 2019 [10]	-	*	-	**	*	-	*	*	*	7
Case-control studies	Adequate case definition	Representativeness of the cases	Selection of Controls	Definition of Controls	Study controls for most important factor	Study controls for an additional factor	Ascertainment of exposure	The same method of ascertainment for cases and controls	The same non-response rate for both groups	Total score
Michaeli et al. 2022 [62]	*	-	*	*	-	-	*	*	-	5
Cross-sectional studies	Representativeness of the sample	Sample size	Response rate	Ascertainment of the exposure	Study Controls for Relevant Confounders (Age, SES, Health)	Study Controls for Additional Factors (i.e. Stress)	Assessment of the outcome	Statistical test		Total score
Erdman et al. 2017 [63]	*	-	-	**	-	-	**	*		6
Flannagan et al. 2016 [64]	*	-	-	**	*	-	**	*		7
Kresovich et al. 2018 [58]	*	-	*	**	-	*	**	*		8
Latour et al. 2020 [65]	*	*	*	**	*		**	*		9
Lane Cordova et al. 2017 [59]	*	*	*	*	*	-	**	*		8
Parks et al. 2011 [66]	-	-	*	**	*	*	**	*		8
Pollack et al. 2018 [60]	*	*	*	**	*	-	**	*		9
Ryan et al. 2018 [61]	-	*	-	*	*	-	**	*		6

* = 1 score point in the Newcastle-Ottowa Scale

^aWells GA, Shea B, O’Connell D, Peterson J, Welch V, Losos M, et al. The Newcastle-Ottawa Scale (NOS) for assessing the quality of nonrandomized studies in meta-analyses. Oxford; 2000