Table 6. Four cases of observational studies were selected after the quality appraisal phase.

	Representative of the population	Exposure of interest clearly defined	Comparison group clearly defined	Selection of the non-exposed	Confounding factors adjusted for in the analysis	Outcome of interest clearly defined	Follow-up periods similar across all participants	Ascertainment of exposure	Outcome was not known at the start of the study	Published in an indexed journal	Score
Park et al. (2018) [25]	Yes	Yes	No	No	No	Yes	Yes	Yes	No	Yes	6/10
Polewczyk et al. [26]	Yes	Yes	No	No	Yes	Yes	Yes	Yes	Unclear	Yes	7/10
Nowosielecka et al. (2022) [27]	Yes	Yes	No	No	Yes	Yes	Yes	Yes	No	Yes	7/10
Pecha et al.  (2021) [28]	Yes	Yes	Yes	Yes	No	Yes	Yes	Yes	No	Yes	8/10