Table 2.

Main results of this meta-analysis

	No. of studies	RR (95% CI)	P Value	I 2 (%)	P heterogeneity
Overall	24	1.29 (1.20-1.37)	< 0.00001	21	0.18
Man	11	1.35 (1.16-1.58)	0.0001	23	0.23
Women	12	1.29 (1.19-1.40)	< 0.00001	0	0.77
Adjusted for
Age	18	1.34 (1.24-1.44)	< 0.00001	3	0.42
Smoke	16	1.36 (1.22-1.52)	< 0.00001	37	0.07
Alcohol use	5	1.40 (1.15-1.71)	0.0009	64	0.02
History of benign thyroid disease	4	1.51 (1.24-1.83)	< 0.0001	0	0.75