Table 5.

Effect of vitamin E supplementation on risk of total, low-grade, and high-grade prostate cancer within quintiles of baseline toenail selenium concentration

Quintile	Supplementation effect			Quintiles	Supplementation effect
	Total	Low-grade	High-grade		Total	Low-grade	High-grade
	HR (95% CI)*	HR (95% CI)*	HR (95% CI)*		HR (95% CI)*	HR (95% CI)*	HR (95% CI)*
Vitamin E vs placebo
No. (subcohort, case patients)†
	(1569, 879)	(1569, 518)	(1569, 230)
Q1‡	1.39 (0.81 to 2.38)	1.20 (0.65 to 2.20)	1.63 (0.74 to 3.61)	Q1–Q2	1.63 (1.11 to 2.40)	1.46 (0.95 to 2.25)	2.11 (1.22 to 3.65)
Q2	1.92 (1.13 to 3.26)	1.77 (0.97 to 3.22)	2.79 (1.33 to 5.88)	Q3–Q5	0.96 (0.71 to 1.28)	0.90 (0.64 to 1.25)	0.90 (0.60 to 1.36)
Q3	0.93 (0.57 to 1.53)	0.94 (0.54 to 1.64)	0.74 (0.38 to 1.43)
Q4	0.97 (0.59 to 1.59)	0.76 (0.43 to 1.34)	1.19 (0.57 to 2.47)
Q5	0.98 (0.58 to 1.66)	1.00 (0.55 to 1.81)	0.85 (0.38 to 1.94)
P interaction§	.13	.24	.12		.03	.08	.02

* Adjusted for age and race by matching. Adjusted for family history of prostate cancer, diabetes, body mass index, and prostate-specific antigen in statistical model.

† Numbers in subcohort and of case patients within each table cell are given in Supplementary Appendix Table 1 (available online).

‡ Quintile cutpoints for toenail selenium (μg/g) are 0.758, 0.832, 0.901, and 1.003.

§ Two-Sided P value for Cox regression coefficients for the cross-product of treatment with a linear term for quintile of toenail selenium. In a posteriori contrasts for low vs high categories of baseline toenail Se, two-sided P value for Cox regression coefficients for the cross-product of treatment with categorized toenail selenium.