Table 2.

Quality of cross-sectional studies included in this systematic review

	Zhao et al. 202026	Coelho et al. 202027	Çağlar et al. 202028	Tabah et al. 202029	Jiang et al. 202030	Hu et al. 202031	Ong et al. 202032	Metin et al. 202033	Guertler et al. 202034	Yildiz et al. 202035
1. Were the criteria for inclusion in the sample clearly defined?	Χ	X	X		X		X
2. Were the study subjects and the setting described in detail?	Χ	X	X	X	X		X	X	X	X
3. Was the exposure measured in a valid and reliable way?
4. Were objective, standard criteria used for measurement of the condition?
5. Were confounding factors identified?		X	X		X		X
6. Were strategies to deal with confounding factors stated?		X	X		X		X
7. Were the outcomes measured in a valid and reliable way?
8. Was appropriate statistical analysis used?	X	X	X	X	X	X	X	X	X	X
Total quality	Poor	Moderate	Moderate	Poor	Moderate	Poor	Moderate	Poor	Poor	Poor
	Singh et al. 202036	Battista et al. 202037	Lin et al. 202038	Zuo et el. 202039
1. Were the criteria for inclusion in the sample clearly defined?			X
2. Were the study subjects and the setting described in detail?	X	X	X
3. Was the exposure measured in a valid and reliable way?
4. Were objective, standard criteria used for measurement of the condition?
5. Were confounding factors identified?			X	Χ
6. Were strategies to deal with confounding factors stated?			X	Χ
7. Were the outcomes measured in a valid and reliable way?	X
8. Was appropriate statistical analysis used?	X	X	X	Χ
Total quality	Poor	Poor	Moderate	Poor