Table 2.

Quality of included studies

	Selection				Comparability		Exposure
Author/year published	Adequate Case Definition	Representative of cases	Selection of controls	Definition of Controls	Age	Other factors	Ascertainment of exposure	Same ascertainment	Non-Response Rate	Total
Craig 2002 [26]	*	*		*	*	*	*	*	*	8
Diejomaoh 2007 [27]	*	*		*	*	*	*	*	*	8
Baban 2010 [23]	*			*			*	*	*	5
Celik 2011 [25]	*	*		*	*	*	*	*	*	8
Wang 2011 [38]	*			*			*	*	*	5
Maryam 2012 [36]	*			*	*	*	*	*	*	7
Hong 2013 [30]	*			*			*	*	*	5
Ispasoiu 2013 [31]	*			*			*	*	*	5
Kazerooni 2013 [34]	*				*	*	*	*	*	6
Ota 2014 [37]	*			*	*		*	*	*	6
El-Dorf 2016 [29]	*			*			*	*	*	5
Jiao 2016 [33]	*			*	*		*	*	*	6
Azizi 2019 [22]	*						*	*	*	4
Lin 2019 [35]	*			*			*	*	*	5
Bahia 2020 [24]	*		*	*	*	*	*	*	*	8
Edugbe 2020 [28]	*			*	*		*	*	*	6
Jiang 2021 [32]	*			*			*	*	*	5
Habets 2022 [39]	*			*			*	*	*	5
Singh 2022 [40]	*			*	*	*	*	*		6