Table 1.
Characteristics of participants at baseline, according to random assignment to vitamin D or placebo groups
| Characteristic | Total (n = 25 871) | Vitamin D group (n = 12 927) | Placebo group (n = 12 944) | P |
|---|---|---|---|---|
| Female sex, No. (%) | 13085 (50.58) | 6547 (50.65) | 6538 (50.51) | .83 |
| Age, mean (SD), y | 67.14 (7.06) | 67.13 (7.05) | 67.14 (7.08) | .84 |
| Race or ethnic group, No. (%)a | .96 | |||
| Non-Hispanic white | 18046 (71.32) | 9013 (71.27) | 9033 (71.37) | |
| Black | 5106 (20.18) | 2553 (20.19) | 2553 (20.17) | |
| Nonblack Hispanic | 1013 (4.00) | 516 (4.08) | 497 (3.93) | |
| Asian | 388 (1.53) | 188 (1.49) | 200 (1.58) | |
| Native American or Alaskan native | 228 (0.90) | 118 (0.93) | 110 (0.87) | |
| Other or unknown | 523 (2.07) | 259 (2.05) | 264 (2.09) | |
| Falls in the past year, No. (%) | 0.08 | |||
| No falls | 13256 (66.74) | 6561 (66.71) | 6695 (67.32) | |
| One fall | 4138 (20.83) | 2095 (21.13) | 2043 (20.54) | |
| Two or more falls | 2467 (12.42) | 1260 (12.71) | 1207 (12.14) | |
| Body mass index, mean (SD), kg/m2 | 28.10 (5.74) | 28.12 (5.68) | 28.07 (5.79) | .50 |
| Body mass index, No. (%), kg/m2 | .24 | |||
| < 18.5 | 226 (0.89) | 113 (0.90) | 113 (0.89) | |
| 18.5-24.9 | 7482 (29.63) | 3703 (29.34) | 3779 (29.92) | |
| 25-29.9 | 10097 (39.98) | 5047 (39.98) | 5050 (39.98) | |
| 30-34.9 | 4669 (18.49) | 2352 (18.63) | 2317 (18.34) | |
| 35+ | 2780 (11.01) | 1408 (11.15) | 1372 (10.86) | |
| Parental history of hip fracture, No. (%) | 3186 (12.31) | 1549 (11.98) | 1637 (12.65) | .10 |
| History of fragility fracture, No. (%) | 2578 (9.96) | 1287 (9.96) | 1291 (9.97) | .96 |
| Diabetes history, No. (%) | 3549 (13.74) | 1812 (14.04) | 1737 (13.44) | .16 |
| Use of diabetic medication, No. (%) | 2728 (10.55) | 1386 (10.73) | 1342 (10.37) | .35 |
| Cataract history, No. (%) | 6377 (24.87) | 3225 (25.17) | 3152 (24.57) | .27 |
| Macular degeneration history, No. (%) | 686 (2.68) | 347 (2.71) | 339 (2.65) | .74 |
| Rheumatoid arthritis history, No. (%) | 1118 (4.38) | 556 (4.36) | 562 (4.40) | .87 |
| Multiple sclerosis history, No. (%) | 51 (0.20) | 24 (0.19) | 27 (0.21) | .68 |
| Parkinson disease history, No. (%) | 76 (0.30) | 45 (0.35) | 31 (0.24) | .11 |
| Use of antihypertensive medications, No. (%) | 13166 (51.23) | 6529 (50.87) | 6637 (51.59) | .25 |
| Current use of SSRIs, No. (%) | 1621 (6.39) | 821 (6.49) | 800 (6.30) | .55 |
| Taken an antidepressant or had counseling in past 2 y | 2856 (27.37) | 1419 (27.51) | 1437 (27.24) | .76 |
| Current smoking, No. (%) | 1836 (7.20) | 921 (7.24) | 915 (7.17) | .88 |
| Alcohol use, No. (%) | .99 | |||
| Never | 7994 (31.43) | 3977 (31.31) | 4017 (31.55) | |
| Rarely to weekly | 1909 (7.50) | 941 (7.41) | 968 (7.60) | |
| 1-6/wk | 8896 (34.97) | 4511 (35.51) | 4385 (34.44) | |
| Daily | 6638 (26.10) | 3274 (25.77) | 3364 (26.42) | |
| Baseline multivitamin use | 11406 (44.84) | 5750 (45.23) | 5656 (44.44) | .20 |
| Baseline calcium intake ≤ 1200 mg/d, No. (%)b | 5166 (19.97) | 2627 (20.32) | 2539 (19.62) | .16 |
| Baseline vitamin D intake ≤ 800 IU/d, No. (%)b | 11030 (42.63) | 5497 (42.52) | 5533 (42.75) | .72 |
| In general would you say your health is: | .95 | |||
| Excellent | 6991 (29.06) | 3507 (29.25) | 3484 (28.87) | |
| Very good | 10760 (44.72) | 5335 (44.49) | 5425 (44.95) | |
| Good | 5386 (22.39) | 2672 (22.28) | 2714 (22.49) | |
| Fair | 865 (3.60) | 451 (3.76) | 414 (3.43) | |
| Poor | 58 (0.24) | 26 (0.22) | 32 (0.27) | |
| Milk (servings/d), mean (SD) | 0.71 (0.91) | 0.71 (0.89) | 0.72 (0.92) | .23 |
| Dark meat fish and canned tuna (servings/d), mean (SD) | 0.15 (0.26) | 0.15 (0.28) | 0.15 (0.25) | .83 |
| Other fish and seafood (servings/d) | 0.16 (0.33) | 0.16 (0.35) | 0.16 (0.31) | .49 |
| Vitamin D fortified food (servings/d), mean (SD) | 0.63 (0.78) | 0.63 (0.79) | 0.64 (0.77) | .41 |
| Total 25(OH)D, (SD) (n = 16 757), nmol/L | 76.7 (25) | 76.8 (25) | 76.6(25) | .65 |
| Free 25(OH)D, (SD) (n = 5131), pmol/L | 15.04 (5.3) | 15.03 (5.35) | 15.05 (5.25) | .81 |
Abbreviations: 25(OH)D, 25-hydroxyvitamin D; SSRI, selective serotonin reuptake inhibitor.
aRace and ethnic groups self-reported by participants.
bCalcium supplement intake less than or equal to 1200 mg/d, vitamin D intake less than or equal to 800 IU/d.