Table 2.

Quality of the included studies

No.	Author, year, reference number	Selection				Compatibility	Exposure			Total score (9)	Rating (High, moderate, low quality)
		Is the case definition adequate?	Representativeness of the cases	Selection of controls	Definition of controls		Ascertainment of exposure	Same method of ascertainment for cases and controls	Non-response rate
1.	Ahmad et al., 2016, [25]	✵	✵			✵✵	✵	✵	✵	7	High
2	Ahmad et al., 2019, [30]	✵	✵			✵✵	✵	✵	✵	7	High
3.	Assir et al., 2014, [26]	✵	✵			✵✵	✵	✵	✵	7	High
4.	Barua and Gill, 2016, [27]	✵	✵			✵✵	✵	✵	✵	7	High
5.	Carme et al., 2009, [28]	✵	✵			✵	✵	✵	✵	6	Adequate
6.	Epelboin et al., 2012, [11]	✵	✵			✵✵	✵	✵	✵	7	High
7.	Halsey et al., 2016, [29]	✵	✵			✵✵	✵	✵	✵	7	High
8.	Kamath et al., 2019, [31]	✵	✵			✵	✵	✵	✵	6	Adequate
9.	Magalhaes et al., 2012, [13]	✵	✵			✵	✵	✵	✵	6	Adequate
10.	Magalhaes et al., 2014, [14]	✵	✵			✵✵	✵	✵	✵	7	High
11.	Mohapatra et al., 2012, [15]	✵	✵			✵✵	✵	✵	✵	7	High
12.	Sonkar et al., 2019, [32]	✵	✵			✵	✵	✵	✵	6	Adequate
13.	Verma et al., 2016, [33]	✵	✵			✵✵	✵	✵	✵	7	High

✵ A star rating