Table 5.

Hazard ratios (HR) and 95% confidence intervals (CIs) for the association between vitamin D–related exposures and breast cancer within 5 y (1,699 cases, 49,044 noncases).

Characteristic	Noncases $n$ (%)	Cases $n$ (%)	HR (95% CI)
Total vitamin D intake ($\text{supplement}+\text{diet}$)a
$<200\text{IU}$	15,370 (33)	507 (31)	1.00
$200–399\text{IU}$	8,095 (17)	283 (17)	1.01 (0.87, 1.17)b
$400–599\text{IU}$	14,621 (31)	540 (33)	0.99 (0.87, 1.12)b
$\ge 600\text{IU}$	8,999 (19)	312 (19)	0.90 (0.78–1.05)b
Per $100\text{IU}$			0.99 (0.97, 1.01)b
Regular vitamin D supplementationc,d
No	22,239 (47)	778 (47)	1.00
Yes	25,264 (53)	876 (53)	0.89 (0.81, 0.99)c
Hours per week doing any sports/exercise (including walking)e
0–2 h/wk	4,735 (10)	177 (11)	1.00
$>2–5\mathrm{h}/\mathrm{wk}$	9,570 (20)	315 (19)	0.87 (0.73, 1.05)
$>5–10\mathrm{h}/\mathrm{wk}$	17,720 (37)	627 (37)	0.93 (0.79, 1.10)
$>10\mathrm{h}/\mathrm{wk}$	16,463 (34)	562 (33)	0.90 (0.76, 1.08)
Per h/wk			1.00 (0.99, 1.01)
Latitude, current residencef
$\le 34°$	12,864 (26)	427 (25)	1.00
35–39°	12,885 (26)	457 (27)	1.05 (0.92, 1.20)
40–42°	14,380 (29)	499 (29)	1.03 (0.91, 1.18)
$>42°$	8,754 (18)	314 (19)	1.06 (0.91, 1.23)
Per degree			1.01 (1.00, 1.01)
Hours spent outdoors per yearg
0–320	12,498 (26)	452 (27)	1.00
321–530	11,195 (23)	404 (24)	1.02 (0.89, 1.16)
531–850	12,424 (26)	415 (25)	0.94 (0.82, 1.08)
$>850$	12,222 (25)	405 (24)	0.93 (0.81, 1.07)
Per 200 h/y			0.99 (0.97, 1.02)

Note: All covariates in the table were assessed during the baseline interview, unless otherwise specified. A total of 141 women were excluded because they were diagnosed with breast cancer before the completion of follow-up or because they provided no follow-up information beyond baseline. Numbers in columns are those with complete data for the specified analysis. IU, international units.

^aAdjusted for age, race, education, physical activity, body mass index (BMI), menopausal status, current birth control use, current hormone therapy type, current alcohol use, total energy intake, osteoporosis, parity, and a BMI × menopausal status interaction term. We excluded 1,137 women with missing dietary data (1,105 noncases, 32 cases) and 439 women with total energy intake $<400$ or $>4000\text{kcal}$ per day (427 noncases, 12 cases).

^bObserved a violation of the proportional hazards assumption ($p<0.05$) for likelihood ratio test of time interaction term.

^cAdjusted for age, race, education, physical activity, BMI, menopausal status, current birth control use, current hormone therapy type, current alcohol use, osteoporosis, parity, and a BMI × menopausal status interaction term.

^dWomen who took a multivitamin or separate vitamin D supplement $\ge 4$ times per week were considered regular users.

^eAdjusted for age, race, education, BMI, menopausal status, current birth control use, current hormone therapy type, current alcohol use, osteoporosis, parity, and a BMI × menopausal status interaction term.

^fAdjusted for age, race, education.

^gAdjusted for age, race, education, physical activity, hours walked per week, BMI, current birth control use, current hormone therapy type, current alcohol use, menopausal status, parity, osteoporosis, and a BMI × menopausal status interaction term.