Table 5. Two cases of case-control studies were selected after the quality appraisal phase.

	Zhou et al. (2021) [14]	Zabak et al. (2020) [24]
Case defined properly	Yes	Yes
Control defined properly	Yes	Yes
Exposure and outcome defined properly	Yes	Yes
Similarities between the groups	No	No
Chances of the groups being exposed to the exposure	Yes	Yes
The exposure and outcomes measured the same way in both groups	Yes	Yes
Follow-up done correctly	Yes	No
Is the study published in an indexed journal?	Yes	Yes
Score	7/8	6/8