TABLE 2.
Effects of vitamin D3 compared with placebo on change in primary study outcomes and related measures of vitamin D metabolism1
| Placebo (n = 167) | Vitamin D3 (n = 499) | Difference in change from baseline2 | ||||||
|---|---|---|---|---|---|---|---|---|
| Baseline3 | After treatment3 | Change from baseline, mean (SD)4 | Baseline3 | After treatment3 | Change from baseline, mean (SD)4 | Mean difference (95% CI) | P 5 | |
| Primary study outcomes | ||||||||
| PTH, pg/mL | 44 (20) | 46 (24) | 2 (18) | 49 (29) | 46 (26) | –3 (16) | –5 (–8, –2) | <0.001 |
| Total 1,25(OH)2D, pg/mL | 50 (17) | 50 (15) | –1 (17) | 50 (19) | 52 (19) | 2 (16) | 2 (–1, 5) | 0.133 |
| Related measures of vitamin D metabolism | ||||||||
| Total 25(OH)D, ng/mL | 29 (10) | 28 (10) | –2 (6) | 30 (11) | 41 (11) | 11 (10) | 12 (10, 14) | <0.001 |
| Bioavailable 25(OH)D, ng/mL | 3.6 (1.2) | 3.3 (1.2) | –0.2 (0.7) | 3.7 (1.3) | 5.0 (1.4) | 1.3 (1.3) | 1.5 (1.3, 1.7) | <0.001 |
| 24,25(OH)2D3, pg/mL | 1.8 (1.0) | 1.6 (0.9) | –0.2 (0.6) | 1.9 (1.1) | 2.9 (1.6) | 1.1 (1.3) | 1.2 (1.0, 1.4) | <0.001 |
| VDMR, pg/ng | 62 (21) | 58 (21) | −3 (11) | 60 (23) | 72 (22) | 12 (16) | 15 (12, 17) | <0.001 |
| VDBP, μg/mL | 226 (31) | 227 (33) | 1 (19) | 223 (30) | 223 (36) | 0 (25) | 0 (-4, 4) | 0.965 |
| Albumin, mg/dL | 4.2 (0.3) | 4.1 (0.3) | 0 (0.2) | 4.2 (0.2) | 4.1 (0.2) | 0 (0.2) | 0 (0, 0) | 0.503 |
| Calcium, mg/dL | 9.4 (0.4) | 9.5 (0.4) | 0 (0.3) | 9.5 (0.4) | 9.5 (0.4) | 0 (0.3) | 0 (-0.1, 0.1) | 0.898 |
| Phosphorus, mg/dL | 3.3 (0.5) | 3.4 (0.5) | 0 (0.5) | 3.4 (0.4) | 3.4 (0.6) | 0.1 (0.5) | 0 (-0.1, 0.1) | 0.763 |
| Urine calcium/creatinine, mg/g | 76 (39, 114) | 68 (35, 126) | 1 (70) | 64 (32, 119) | 72 (34, 137) | 8 (83) | 7 (-8, 21) | 0.358 |
PTH, parathyroid hormone; VDBP, vitamin D binding protein; VDMR, vitamin D metabolite ratio [24,25(OH)2D3 to 25(OH)D3]; 1,25(OH)2D, 1,25-dihydroxyvitamin D; 25(OH)D, 25-hydroxyvitamin D; 24,25(OH)2D3, 24,25-dihydroxyvitamin D3.
Modeled differences compare participants randomly assigned to vitamin D3 with those randomly assigned to placebo, and account for missing data using multiple imputation.
Calculated using participants with complete case data and are shown as mean (SD) except for urine calcium/creatinine, which is median (IQR).
Change from baseline after 16 wk of treatment calculated using participants with complete case data.
Test of the difference in change in vitamin D metabolism measured from baseline after 16 wk of treatment.