Table 1. Baseline Characteristics.
| Baseline Characteristic | No. (%)a | ||
|---|---|---|---|
| All participants (N = 25 871) | Vitamin D | ||
| Active (n = 12 927) | Placebo (n = 12 944) | ||
| Female | 13 085 (51) | 6547 (51) | 6538 (51) |
| Age, mean (SD), y | 67.1 (7.1) | 67.1 (7.0) | 67.1 (7.1) |
| Race/ethnicityb | |||
| Non-Hispanic White | 18 046 (71) | 9013 (71) | 9033 (71) |
| Black | 5106 (20) | 2553 (20) | 2553 (20) |
| Nonblack Hispanic | 1013 (4) | 516 (4) | 497 (4) |
| Asian or Pacific Islander | 388 (2) | 188 (2) | 200 (2) |
| American Indian or Alaska Native | 228 (1) | 118 (1) | 110 (1) |
| Other or unknown | 523 (2) | 259 (2) | 264 (2) |
| Body mass index, mean (SD)c | 28.1 (5.7) | 28.1 (5.7) | 28.1 (5.8) |
| <25 | 7843 (31) | 3884 (31) | 3959 (31) |
| 25-<30 | 10 122 (40) | 5060 (40) | 5062 (40) |
| ≥30 | 7289 (29) | 3679 (29) | 3610 (29) |
| Current smoking | 1836 (7) | 921 (7) | 915 (7) |
| Diabetes | 3549 (14) | 1812 (14) | 1737 (13) |
| Any alcohol used | 17 443/25 437 (69) | 8726/12 703 (69) | 8717/12 734 (68) |
| Current use of supplemental vitamin D, ≤800 IU/de | 11 030 (43) | 5497 (43) | 5533 (43) |
| Baseline 25(OH)D, mean (SD), ng/mLf | 30.8 (10.0) | 30.9 (10.0) | 30.8 (10.0) |
| Cancer screening at baseline | |||
| Mammography or breast biopsy within past 10 y among women only | 12 212 (94) | 6089 (94) | 6123 (94) |
| Colonoscopy or other colon cancer screening within past 10 y | 23 055 (90) | 11 523 (90) | 11 532 (90) |
| PSA screening within past 10 y, among men only | 9586 (77) | 4771 (77) | 4815 (77) |
SI conversion factor: To convert 25(OH)D from ng/mL to nmol/L, multiply by 2.5.
a
Percentages may not sum to 100 because of rounding or because of missing values for cancer screening. There were no significant differences between the groups with regard to the baseline characteristics.
b
Race and ethnicity were reported by the participants.
c
Calculated as weight in kilograms divided by height in meters squared. Data were missing for 2.4% of the participants.
d
Includes any alcohol use, at least monthly.
e
From all supplemental sources of vitamin D combined (individual vitamin D supplements, calcium + vitamin D supplements, medications with vitamin D, and multivitamins).
f
N = 15 787 with measured values.