Table S2. Quality assessment of included studies using the EPHPP tool*.

Author/year	Overall quality assessment	Quality assessment for study components
		Selection bias	Study design	Data collection methods	Confounders
Sunnetcioglu 2018	Strong	Strong	Moderate	Strong	Moderate
Song 2016	Strong	Strong	Moderate	Strong	Moderate
Uygur 2016	Strong	Strong	Moderate	Strong	Moderate
Altintas 2015	Strong	Strong	Moderate	Moderate1	Strong
Korkmaz 2015	Strong	Strong	Moderate	Strong	Strong
Koseoglu 2015	Strong	Strong	Moderate	Strong	Moderate
Koseoglu 2015	Strong	Strong	Moderate	Strong	Strong
Yenigun 2015	Strong	Strong	Moderate	Strong	Strong
Sökücü 2014	Strong	Strong	Moderate	Strong	Moderate
Kanbay 2013	Strong	Strong	Moderate	Strong	Moderate
Karakas 2013	Strong	Strong	Moderate	Strong	Strong
Kurt 2013	Strong	Strong	Moderate	Strong	Moderate
Nena 2012	Strong	Strong	Moderate	Strong	Strong
Ozsu 2012	Strong	Strong	Moderate	Strong	Moderate
Varol2011	Strong	Strong	Moderate	Strong	Moderate
Varol2010	Strong	Strong	Moderate	Strong	Moderate
Choi 2006	Strong	Strong	Moderate	Strong	Strong

*, EPHPP: Effective Public Health Practice Project tool (Hamilton, Ontario, Canada); ¹, original data was based on median (Q25–Q75), and we changed it into mean ± SD, according to the Cochrane handbook.