Table 2.

Meta-Analysis of Studies Regarding the Relationship between Selenium and Prostate Cancer Based on Country, Type of study and sample of selenium. random effects model

Variable		Study(Na)	Case	Control	I2(%)	95% CIb	RRc
Country	USA	23	31,691	70,385	51.6	0.78,1.02	0.89
	Austria	1	70	80		0.21,2.60	0.74
	United Kingdim	1	300	300		0.73,2.10	1.24
	Hawaii	1	450	936		0.59,1.14	0.82
	Europe	1	959	1,059		0.22,4.15	0.96
	China	1	133	265		0.98,1.02	1
	Iran	1	62	68		0.06,0.45	0.16
	Finland	1	317	28,816		0.43,1.66	0.84
	Sweden	1	164	121		0.11,0.79	0.3
	Denmark	1	784	784		0.94,1.08	1.01
	Netherlands	2	540	1,211	84.4	0.27,0.92	0.5
Type of study	Case-control	19	8,639	16,967	59.1	0.80,1.00	0.89
	Cohort	6	3,786	66,682	85.5	0.52,1.14	0.77
	Randomized controlled trial	9	23,994	21,644	54.3	0.74,1.09	0.9
Sample of selenium	Serum	6	1,983	2,913	62.5	0.51,0.95	0.69
	Plasma	6	2,982	2,637	70.1	0.61,1.17	0.85
	Nail	6	2,189	3263	74.8	0.41,1.05	0.66
	Diet	7	5,206	74,814	0	0.98,1.02	1
	Selenium supplement and placebo	9	23,994	21,644	54.3	0.74,1.09	0.9

^a, Number ;

^b, Confidence interval ;

^c, Relative risk