Table 1.
Characteristics of participants at baseline by strata of achieved serum 25(OH)D concentration
| Level at 3 mo (ng/mL) | Absolute change from BL to 3 mo (FU-BL; ng/mL) | Relative change from BL to 3 mo (FU-BL)/BL; %) | |||||||
|---|---|---|---|---|---|---|---|---|---|
| ≤29 (N = 299) |
30-39 (N = 242) |
>40 (N = 96) |
Lower 25%: -9 to 2 (N = 147) |
Middle 50%: 3-14 (N = 350) |
Upper 25%: 15-66 (N = 140) |
Lower 25%: -36 to 10 (N = 159) |
Middle 50%: 11-70 (N = 320) |
Upper 25%: 71-455 (N = 158) |
|
| Age, mean ± SD, y | 77.1 ± 5.3 | 76.9 ± 5.2 | 77.8 ± 6.0 | 77.0 ± 5.2 | 77.1 ± 5.3 | 77.4 ± 5.5 | 77.2 ± 5.4 | 76.8 ± 5.3 | 77.8 ± 5.3 |
| Female, no. | 121 (40.5%) | 106 (43.8%) | 47 (49.0%) | 58 (39.5%) | 147 (42.0%) | 69 (49.3%) | 65 (40.9%) | 132 (41.3%) | 77 (48.7%) |
| Race/ethnicitya, no. | |||||||||
| White, non-Hispanic | 234 (79.6%) | 183 (76.9%) | 76 (80.9%) | 118 (81.4%) | 268 (78.1%) | 107 (77.5%) | 128 (81.5%) | 244 (78.0%) | 121 (77.6%) |
| Black | 50 (17.0%) | 47 (19.7%) | 12 (12.8%) | 21 (14.5%) | 62 (18.1) | 26 (18.8%) | 23 (14.6%) | 57 (18.2%) | 29 (18.6%) |
| Other | 10 (3.4%) | 8 (3.4%) | 6 (6.4%) | 6 (4.1%) | 13 (3.8%) | 5 (3.6%) | 6 (3.8%) | 12 (3.8%) | 6 (3.8%) |
| No. missing | 5 | 4 | 2 | 2 | 7 | 2 | 2 | 7 | 2 |
| High school graduate or less, no. | 51 (17.1%) | 47 (19.4%) | 20 (20.8%) | 16 (10.9%) | 66 (18.9%) | 36 (25.7%) | 17 (10.7%) | 55 (17.2%) | 46 (29.1%) |
| Married or like relationship, no. | 176 (58.9%) | 124 (51.2%) | 48 (50.0%) | 91 (61.9%) | 197 (56.3%) | 60 (42.9%) | 97 (61.0%) | 178 (55.6%) | 73 (46.2%) |
| BMI (kg/m2), mean ± SD | 31.2 ± 6.0 | 30.1 ± 5.6 | 30.2 ± 6.8 | 31.0 ± 6.0 | 30.6 ± 6.1 | 30.0 ± 5.8 | 30.8 ± 6.0 | 30.8 ± 6.1 | 29.9 ± 5.8 |
| No. missing | 1 | 0 | 0 | 0 | 1 | 0 | 0 | 1 | 0 |
| Current cigarette smoker, no. | 6 (2.0%) | 8 (3.3%) | 5 (5.2%) | 2 (1.4%) | 12 (3.4%) | 5 (3.6%) | 3 (1.9%) | 10 (3.1%) | 6 (3.8%) |
| Alcoholic drinks/wk, median (Q25, Q75) | 0 (0, 3) | 0 (0,4) | 0 (0, 5) | 0 (0, 4) | 0 (0, 3) | 0 (0, 4) | 0 (0, 4) | 0 (0, 3) | 0 (0, 4) |
| SPPBb score, median (Q25, Q75) | 9 (8, 10) | 9 (8,11) | 9 (7, 10) | 9 (8, 10) | 9 (8, 11) | 9 (7.5, 10) | 9 (8, 11) | 9 (8, 11) | 9 (7, 10) |
| Gait speed (m/s), mean ± SD | 0.86 ± 0.24 | 0.88 ± 0.22 | 0.86 ± 0.24 | 0.88 ± 0.23 | 0.87 ± 0.24 | 0.85 ± 0.23 | 0.88 ± 0.23 | 0.88 ± 0.24 | 0.84 ± 0.23 |
| No. missing | 1 | 1 | 0 | 0 | 1 | 1 | 0 | 1 | 1 |
| No. of morbid conditions, median (Q25, Q75)c | 3 (2, 4) | 3 (2, 4) | 3 (2, 4) | 3 (2, 4) | 3 (2, 4) | 3 (2, 4) | 3 (2, 4) | 3 (2, 4) | 3 (2, 4) |
| Frailty statusd, no. (%) | |||||||||
| Robust | 88 (29.5%) | 71 (29.3%) | 31 (32.3%) | 43 (29.3%) | 105 (30.1%) | 42 (30.0%) | 44 (27.7%) | 103 (32.3%) | 43 (27.2%) |
| Prefrail | 175 (58.7%) | 144 (59.5%) | 55 (57.3%) | 91 (61.9%) | 201 (57.6%) | 82 (58.6%) | 101 (63.5%) | 177 (55.5%) | 96 (60.8%) |
| Frail | 35 (11.7%) | 27 (11.2%) | 10 (10.4%) | 13 (8.8%) | 43 (12.3%) | 16 (11.4%) | 14 (8.8%) | 39 (12.2%) | 19 (12.0%) |
| No. missing | 1 | 0 | 0 | 0 | 1 | 0 | 0 | 1 | 0 |
| Study site location, no. | |||||||||
| Hagerstown, MD | 137 (45.8%) | 113 (46.7%) | 48 (50.0%) | 62 (42.2%) | 164 (46.9%) | 72 (51.4%) | 60 (37.7%) | 155 (48.4%) | 83 (52.5%) |
| Baltimore, MD | 162 (54.2%) | 129 (53.3%) | 48 (50.0%) | 85 (57.8%) | 186 (53.1%) | 68 (48.6%) | 99 (62.3%) | 165 (51.6%) | 75 (47.5%) |
| 25(OH)D (ng/mL) | |||||||||
| Median (Q25, Q75) | 22 (17, 25) | 24.5 (21, 28) | 23 (18.5, 27) | 25 (23, 27) | 23 (19, 26) | 20 (15, 24) | 26 (23, 28) | 23 (20, 26) | 17 (14, 21) |
| Mean ± SD | 20.9 ± 5.1 | 23.6 ± 4.6 | 22.3 ± 5.1 | 24.6 ± 3.5 | 22.1 ± 5.0 | 19.6 ± 5.4 | 25.1 ± 3.4 | 22.8 ± 4.4 | 17.9 ± 5.0 |
| Dietary vitamin De (IU/d), median (Q25, Q75) | 182 (118, 276) |
178 (104, 286) |
162 (108, 260) |
194 (126, 301) |
180.5 (103.5, 280.5) |
146 (101, 260) |
201 (127, 304) |
182.5 (106, 285) |
147 (95, 237) |
| No. missing | 2 | 0 | 1 | 0 | 2 | 1 | 0 | 2 | 1 |
| Personal supplemental vitamin D (IU/d) | |||||||||
| Any, no. | 93 (31.1%) | 113 (46.7%) | 33 (34.4%) | 69 (46.9%) | 134 (38.3%) | 36 (25.7%) | 78 (49.1%) | 128 (40.0%) | 33 (20.9%) |
| For those with any, median (Q25, Q75) | 700 (400, 1000) | 800 (500, 1000) | 600 (429, 1000) | 643 (400, 1000) | 800 (500, 1000) | 586 (400, 900) | 700 (400, 1000) | 800 (500, 1000) | 571 (400, 800) |
| Month randomized, no.f | |||||||||
| January, February, or March | 47 (15.7%) | 33 (13.6%) | 18 (18.8%) | 23 (15.7%) | 49 (14.0%) | 26 (18.6%) | 28 (17.6%) | 46 (14.4%) | 24 (15.2%) |
| April, May, June | 111 (37.1%) | 109 (45.0%) | 43 (44.8%) | 47 (32.0%) | 152 (43.4%) | 64 (45.7%) | 49 (30.8%) | 137 (42.8%) | 77 (48.7%) |
| July, August, September | 89 (29.8%) | 61 (25.2%) | 27 (28.1%) | 45 (30.6%) | 93 (26.6%) | 39 (27.9%) | 45 (28.3%) | 87 (27.2%) | 45 (28.5%) |
| October, November, December | 52 (17.4%) | 39 (16.1%) | 8 (8.3%) | 32 (21.8%) | 56 (16.0%) | 11 (7.9%) | 37 (23.3%) | 50 (15.6%) | 12 (7.6%) |
To convert 25(OH)D ng/ml to nmol/L, multiply ng/mL by 2.5.
Abbreviations: 25(OH)D, 25-hydroxyvitamin D; BL, baseline; BMI, body mass index; FU, follow-up; Q, quartile; SPPB, Short Physical Performance Battery.
a Race/ethnicity was self-reported.
b The SPPB is a 3-part assessment of physical functioning: balance testing, timed 4-m walk at usual pace, and demonstration of ability to complete 5 chair stands; each part is scored 0 to 4, and the total SPPB score (range, 0-12) is the sum of the 3 subscores. Higher scores indicate better physical function.
c Participant was asked about 14 morbid conditions (“have you ever been told by a physician that you had”): cancer other than basal cell skin cancer, heart disease, high cholesterol, hypertension, stroke, peripheral vascular disease, chronic lung disease, diabetes, kidney disease, liver disease, connective tissue disease, arthritis, Parkinson disease, multiple sclerosis.
d Physical frailty phenotype was determined using the criteria of Fried et al (2001); frailty status is determined based on conditions of weight loss, exhaustion, slow gait speed, low grip strength, and low physical activity; frail (3 conditions present), prefrail (1 or 2 conditions), and robust (no conditions).
e Dietary vitamin D intake was estimated from the modified Calcium and Vitamin D Frequency Questionnaire (Taylor et al, 2009).
f Counts of persons randomized are pooled over 3 mo; however, ≥ 2 persons in each stratum of each classification were randomized during each month.