Table 1.
Baseline Characteristics of Randomized Subjects
| All Subjects n=230 |
Placebo n= 76 |
Low-Dose Vitamin D n= 75 |
High-Dose Vitamin D n= 79 |
P
valuea |
|
|---|---|---|---|---|---|
| Demographic Characteristics | |||||
| Age, years | 61 ± 6 | 61 ± 6 | 60 ± 6 | 60 ± 5 | 0.78 |
| Weight, kg | 81 ± 18 | 81 ± 19 | 82 ± 18 | 80 ± 18 | 0.91 |
| Height, cm | 163 ± 6 | 163 ± 6 | 164 ± 6 | 162 ± 5 | 0.91 |
| Body Mass Index, kg/m2 | 30.8 ± 6.8 | 30.6 ± 6.6 | 31.2 ± 7.4 | 30.7 ± 6.5 | 0.91 |
| Race | |||||
| White | 207 (90%) | 68 (90%) | 67 (89%)b | 72 (91%) | |
| Black | 14 (6%) | 6 (8%) | 7 (9%) | 1 (1%) | |
| Asian | 5 (2%) | 1 (1%) | 1 (1%) | 3 (4%) | 0.74 |
| American Indian/Alaskan | 2 (1%) | 0 (0%) | 0 (0%) | 2 (3%) | |
| Hispanic/Latina | 2 (1%) | 1 (1%) | 0 (0%) | 1 (1%) | |
| Bone Mineral Density Measures | |||||
| Spine, g/cm2 | 1.155 (1.055, 1.286) | 1.143 (1.048, 1.228) |
1.145 (1.080, 1.275) |
1.163 (1.044, 1.280) |
0.91 |
| Spine T-Score | −0.2 (−1.1, +0.9) | −0.3 (−1.1, +0.9) | −0.3 (−0.8, +0.8) | −0.2 (−1.2, +0.9) | 0.91 |
| Hip, g/cm2 | 0.961 (0.900, 1.038) |
0.954 (0.882, 1.025) |
0.961 (0.905, 1.038) |
0.966 (0.911, 1.032) |
0.91 |
| Hip T-Score | −1.0 (−1.5, −0.5) | −1.0 (−1.7, −0.6) | −1.0 (−1.4, −0.4) | −1.1 (−1.6, −0.5) | 0.78 |
| Dietary Habits | |||||
| Kilocalories, kcal/day | 1842 (1539, 2198) | 1943 (1651, 2258) | 1782 (1558, 2045) |
1839 (1497, 2196) |
0.78 |
| Carbohydrates, g/day | 222 (175, 266) | 231 (194, 274) | 215 (171, 261) | 205 (171, 261) | 0.74 |
| Protein, g/day | 75 (62, 86) | 74 (59, 86) | 75 (65, 89) | 76 (64, 86) | 0.91 |
| Fat, g/day | 72 (60, 91) | 77 (58, 96) | 72 (60, 88) | 68 (61, 90) | 0.89 |
| Fiber, g/day | 19 (14, 25) | 21 (15, 28) | 19 (15, 24) | 17 (14, 24) | 0.74 |
| Dietary Calcium, mg/day | 905 (703, 1099) | 929 (777,1110) | 890 (678,1101) | 896 (706,1077) | 0.91 |
| Calcium Supplement, mg/day | 0 (0, 0) | 0 (0, 29) | 0 (0, 0) | 0 (0, 0) | 0.78 |
| All Calcium Intake, mg/day | 967 (752, 1215) | 1007 (808,1306) | 961 (699,1202) | 962 (739,1174) | 0.78 |
| Iron, mg/day | 13 (10, 16) | 14 (11, 16) | 12 (9, 16) | 13 (11, 16) | 0.78 |
| Magnesium, mg/day | 306 (247, 370) | 335 (261, 405) | 289 (244, 337) | 305 (247, 354) | 0.47 |
| Vitamin D, IU/day | 196 (115, 266) | 190 (138, 299) | 176 (115, 254) | 207 (107, 263) | 0.91 |
| Oxalate, servings/day | 0.9 (0.4, 1.8) | 1.1 (0.5, 2.1) | 0.9 (0.4, 1.9) | 0.6 (0.3, 1.4) | 0.46 |
| Serum Laboratory Measures | |||||
| Calcium, mg/dL | 9.1 ± 0.4 | 9.1 ± 0.3 | 9.2 ± 0.4 | 9.1 ± 0.4 | 0.91 |
| Albumin, g/dL | 3.9 ± 0.3 | 4.0 ± 0.3 | 3.9 ± 0.3 | 3.9 ± 0.3 | 0.78 |
| Creatinine, mg/dL | 0.8 ± 0.2 | 0.8 ± 0.2 | 0.8 ± 0.2 | 0.8 ± 0.1 | 0.78 |
| GFR, mL/minute | 79 ± 17 | 79 ± 17 | 77 ± 17 | 80 ± 16 | 0.78 |
| PTH, pg/dL | 41 (30, 54) | 40 (29, 53) | 42 (31, 56) | 42 (33, 52) | 0.78 |
| 25(OH)D, ng/mL | 21 ± 3 | 21 ± 3 | 21 ± 3 | 21 ± 3 | 0.91 |
| 1,25(OH)2D, pg/mLc | 41 (31, 54) | 41 (32, 51) | 42 (32, 55) | 40 (31, 53) | 0.91 |
| Estradiol, pg/mLc | 48 (40, 56) | 49 (40, 58) | 47 (42, 54) | 48 (39, 55) | 0.78 |
P-values were adjusted for multiple comparisons using the Benjamini and Hochberg method to control the false discovery rate.
Percentages do not equal 100 due to rounding.
Denotes measurement of laboratory studies at randomization rather than screening. Data with a normal distribution are summarized using mean and standard deviation, and analyzed using analysis of variance. Data with outliers are summarized using the median (1st, 3rd IQR) and analyzed using the Kruskal-Wallis test.
SI conversion factors: To convert calcium to mmol/L, multiply values by 025. To convert albumin to g/L, multiply values by 10. To convert creatinine to μmol/L, multiply values by 88.4. To convert PTH to ng/L, multiply values by 1. To convert 25(OH)D to nmol/L, multiply values by 2.496. To convert 1,25(OH)2D to pmol/L, multiply values by 2.6. To convert estradiol to pmol/L, multiply values by 3.671. At the UW Primate Center, serum 1,25(OH)2D was extracted, samples were evaporated and derivatized (Amplifex Diene, AB Sciex, Framington, MA) and 30 uL was injected for liquid chromatography-tandem mass spectrometry analysis using a Shimazdu LC system (Columbia, MD) coupled to a QTRAP 5500 equipped with a Turbo V Ion source (AB Sciex) as previously published with an intra and inter-assay variability of 9.3% and 14.1%, respectively. The UW Primate Center measured serum estradiol using an in-house assay. Samples were extracted with ethyl ether, the ether was evaporated and antibody (Holly Hill Biologicals) and trace (Perkin Elmer) were added with overnight incubation. The following day a charcoal solution was added, followed by incubation for 15 minutes, centrifugation, removal of the supernatant, addition of scintillation cocktail and then analysis using a beta counter. For lower estradiol levels typical of postmenopausal women, the intra and inter-assay variability for the assay is 4.5% and 5.8%, respectively. The UW Clinical Laboratory measured PTH using a chemiluminescent immunoassay performed on the Siemens ADIVA Centaur XP. The intra and inter-assay variability for the assay is 4.4% and 6.5%.