TABLE 3.
Associations of baseline characteristics with change in PTH concentration (pg/mL) among participants assigned to vitamin D31
| Change in PTH from baseline, mean (95% CI)3 | Difference in change in PTH (95% CI)2 | ||||
|---|---|---|---|---|---|
| Variable | n | Unadjusted model | Adjusted model4 | P 5 | |
| Age (per decade) | 499 | 0 (–1, 2) | 0 (–2, 2) | 0.785 | |
| Sex | |||||
| Female | 272 | –3 (–5, –1) | Ref | Ref | 0.666 |
| Male | 227 | –3 (–5, –2) | –1 (–4, 2) | 0 (–2, 2) | |
| Race/ethnicity | |||||
| White | 169 | –3 (–6, 0) | Ref | Ref | 0.591 |
| Black | 184 | –4 (–6, –2) | –2 (–5, 2) | –1 (–5, 2) | |
| Hispanic | 82 | –1 (–4, 2) | 2 (–3, 6) | 2 (–3, 6) | |
| Chinese | 64 | –3 (–5, 0) | 0 (–5, 5) | 0 (–5, 5) | |
| BMI (kg/m2) | |||||
| <25 | 127 | –3 (–5, –1) | Ref | Ref | 0.307 |
| 25 to <30 | 189 | –1 (–4, 1) | 2 (–2, 6) | 2 (–2, 6) | |
| 30 to <35 | 107 | –5 (–9, –2) | –2 (–6, 2) | –2 (–6, 3) | |
| ≥35 | 76 | –4 (–7, 0) | 0 (–5, 4) | 0 (–5, 5) | |
| Creatinine (per 0.5 mg/dL) | 499 | –1 (–4, 2) | 0 (–3, 3) | 0.985 | |
| eGFR (per 10 mL/min/1.73m2) | 499 | 0 (–1, 1) | 0 (–1, 1) | 0.643 | |
| Bioavailable 25(OH)D (per 1-ng/mL decrement) | 499 | –3 (–4, –2) | –3 (–5, –2) | <0.001 | |
| 25(OH)D (ng/mL) | |||||
| <20 | 79 | –11 (-15, –6) | –10 (–14, –6) | –10 (–15, –6) | |
| 20 to <30 | 144 | –3 (–5, –1) | –2 (–5, 1) | –2 (–6, 1) | |
| ≥30 | 230 | –1 (–2, 1) | Ref | Ref | <0.001 |
| Per 10-ng/mL decrement | 499 | –4 (–5, –2) | –4 (–5, –3) | <0.001 | |
| VDBP (per 1-SD increment) | 499 | –1 (–2, 1) | –1 (–2, 1) | 0.380 | |
| VDMR tertiles6 | |||||
| Tertile 1 | 149 | –6 (–9, –3) | –4 (–8, –1) | –5 (–8, –1) | |
| Tertile 2 | 155 | –2 (–4, 0) | –1 (–4, 3) | –1 (–5, 3) | |
| Tertile 3 | 149 | –1 (–3, 1) | Ref | Ref | 0.030 |
| Per 1-SD decrement | 499 | –2 (–3, –1) | –2 (–4, –1) | 0.007 | |
eGFR, estimated glomerular filtration rate; PTH, parathyroid hormone; Ref, reference; VDBP, vitamin D binding protein; VDMR, vitamin D metabolite ratio [24,25-dihydroxyvitamin D3 to 25(OH)D3]; 25(OH)D, 25-hydroxyvitamin D.
Modeled estimates account for missing data using multiple imputation.
Change from baseline after 16 wk of vitamin D3 summarized over all participants (n = 499) using multiple imputation. The mean (95% CI) among all vitamin D3 participants was −3 (−4, −2) pg/mL.
Adjusted for age, sex, race/ethnicity, BMI, eGFR, and season at baseline exam, except for the model assessing serum creatinine, which was adjusted for age, sex, race/ethnicity, BMI, and season at baseline exam.
Test statistic for the covariate-adjusted model.
Tertile cutoffs are based on the full study population.