Table 3.

Quality assessment of studies included in the meta-analysis

S. no	Study	Year	Is the case definition adequate?	Representativeness of the cases	Selection of controls	Definition of controls	Comparability of cases and controls on the basis of design or analysis	Ascertainment of exposure	Same method of ascertainment for both groups	Overall NOS scores
1	Uyanik	2002	*	*	*	*	**	*	*	8
2	Piskin	2003	*	*	*	*	*	*	*	7
3	Farshchian	2007	*	*	*	*	**	*	*	8
4	Akhyani	2007	*	*	*	*	**	*	*	8
5	Dreiher	2008	*	*	*	*	**	*	*	8
6	Choi	2010	*	*	*	*	*	*	*	7
7	Balci	2010	*	*	*	*	**	*	*	8
8	Langan	2012	*	*	*	*	**	*	*	8
9	Vaya	2013	*	*	*	*	**	*	*	8
10	Akcali	2014	*	*	*	*	**	*	*	8
11	Pehlevan	2014	*	*	*	*	**	*	*	8
12	Parodi	2014	*	*	*	*	**	*	*	8
13	Sarvtin	2014	*	*	*	*	**	*	*	8
14	Farshchian	2015	*	*	*	*	**	*	*	8
15	Irimie	2015	*	*	*	*	*	*	*	7
16	Coban	2016	*	*	*	*	**	*	*	8
17	Kothiwala	2016	*	*	*	*	*	*	*	7
18	Sharma	2016	*	*	*	*	**	*	*	8
19	Uday	2016	*	*	*	*	*	*	*	7
20	Djurovic	2016	*	*	*	*	**	*	*	8
21	Uczniak	2016	*	*	*	*	**	*	*	8
22	Barrea	2016	*	*	*	*	*	*	*	7
23	Singh	2017	*	*	*	*	*	*	*	7
24	Milcic	2017	*	*	*	*	**	*	*	8
25	Girisha	2017	*	*	*	*	**	*	*	8
26	Ganguly	2018	*	*	*	*	*	*	*	7