Table 3.

The newcastle-ottawa scale (NOS) for quality assessment of the included studies in the meta-analysis.

S. No.		Selection				Comparability	Outcome		Total Quality Score	Overall Quality Assessment (AHRQ standards)
	Study ID	Representativeness of the sample	Sample Size	Non-respondents	Ascertainment of the exposure (risk factor)	Outcome groups are comparable	Assessment of outcomes	Statistical test
	[31]	0	1	1	2	0	1	1	6	Good
1.	[32]	1	0	1	0	0	1	1	4	Good
2.	[33]	1	1	1	1	2	1	1	8	Good
3.	[34]	1	0	1	1	1	1	1	6	Good
4.	[35]	1	1	1	2	2	1	1	9	Good
5.	[36]	1	1	1	2	2	1	1	9	Good
6.	[37]	1	1	1	2	2	1	1	9	Good
7.	[38]	1	1	1	1	1	1	1	7	Good
8.	[39]	1	1	1	1	1	1	1	7	Good
9.	[40]	1	1	1	1	1	1	1	7	Good
10.	[41]	1	1	0	1	1	1	1	6	Good
11.	[42]	1	1	1	2	2	1	1	9	Good
12.	[43]	1	1	1	1	2	1	1	8	Good
13.	[44]	1	1	1	2	2	1	1	9	Good
14.	[45]	1	0	1	2	2	1	1	8	Good
15.	[46]	1	1	1	2	1	1	1	8	Good
16.	[47]	0	0	0	2	1	1	1	5	Fair
17.	[48]	0	0	0	2	1	1	1	5	Fair
18.	[49]	1	1	1	2	2	1	1	9	Good
19.	[50]	0	0	1	2	2	1	1	7	Good
20.	[51]	1	1	1	2	2	1	1	9	Good
21.	[52]	0	0	1	1	2	1	1	6	Good
22.	[53]	1	1	0	1	2	1	1	7	Good
23.	[54]	0	0	0	2	0	1	1	4	Fair
24.	[55]	1	1	1	2	2	1	1	9	Good
25.	[56]	1	1	1	2	2	1	1	9	Good
26.	[57]	1	1	0	1	2	1	1	7	Good
27.	[58]	1	1	1	2	1	1	1	8	Good
28.	[59]	1	1	1	2	2	1	1	9	Good
29.	[60]	1	0	0	0	2	1	1	5	Fair
30.	[61]	1	1	1	1	2	1	1	8	Good
31.	[62]	1	0	0	2	2	1	1	7	Good
32.	[63]	1	1	1	2	2	1	1	9	Good
33.	[64]	1	1	1	1	2	1	1	8	Good
34.	[65]	1	1	0	1	2	1	1	7	Good
35.	[66]	1	1	1	2	2	1	1	9	Good
36.	[67]	1	1	0	2	2	1	1	8	Good
37.	[68]	1	0	1	2	1	1	1	7	Good
38.	[69]	1	1	1	2	2	1	1	9	Good
39.	[70]	1	0	0	1	1	1	1	5	Fair
40.	[71]	1	0	0	1	0	1	1	4	Fair
41.	[72]	1	1	0	0	2	1	1	6	Good
42.	[73]	1	0	0	2	2	1	1	7	Good
43.	[74]	1	1	1	2	2	1	1	9	Good
44.	[75]	0	0	0	2	1	1	1	5	Fair
45.	[76]	1	1	1	1	2	1	1	8	Good