Table 3. Quality assessment of cohort studies.

Questions	Luo et al. (2020) [30]	Irwin et al. (2018) [32]
1. Were the two groups similar and recruited from the same population?	Y	Y
2. Were the exposures measured similarly to assign people to both exposed and unexposed groups?	Y	Y
3. Was the exposure measured in a valid and reliable way?	Y	Y
4.Were confounding factors identified?	Y	Y
5. Were strategies to deal with confounding factors stated?	Y	Y
6. Were the groups/participants free of the outcome at the start of the study (or at the moment of exposure)?	Y	Y
7. Were the outcomes measured in a valid and reliable way?	Y	Y
8. Was the follow up time reported and sufficient to be long enough for outcomes to occur?	Y	Y
9. Was follow up complete, and if not, were the reasons to loss to follow up described and explored?	Y	N
10. Were strategies to address incomplete follow up utilized?	Y	U
11. Was appropriate statistical analysis used?	Y	Y
% Yes	100	83

Abbreviations: Y = Yes; N = No.