Table 5.
Association between plasma 25(OH)D stratified by VDBP, and between VDBP stratified by 25(OH)D, and risk of colorectal cancer in the Nurses' Health Study (1990–2011)
| Analysis | Quartile 1 | Quartile 2 | Quartile 3 | Quartile 4 |
P for trend |
P for interactiona |
|---|---|---|---|---|---|---|
| Total 25(OH)D | ||||||
| Low VDBP b | ||||||
| No. of cases/controls | 65/92 | 62/91 | 39/88 | 28/73 | ||
| Multivariable OR (95% CI)c | 1 (referent) | 0.96 (0.59–1.55) | 0.62 (0.37–1.05) | 0.57 (0.32–1.02) | 0.01 | 0.34 |
| High VDBP b | ||||||
| No. of cases/controls | 50/80 | 43/81 | 47/83 | 44/101 | ||
| Multivariable OR (95% CI)c | 1 (referent) | 0.84 (0.49–1.46) | 0.84 (0.49–1.46) | 0.84 (0.49–1.46) | 0.19 | |
| Free 25(OH)D | ||||||
| Low VDBP b | ||||||
| No. of cases/controls | 35/41 | 39/63 | 48/97 | 72/144 | ||
| Multivariable OR (95% CI)c | 1 (referent) | 0.70 (0.38–1.29) | 0.49 (0.27–0.91) | 0.57 (0.32–1.00) | 0.15 | 0.79 |
| High VDBP b | ||||||
| No. of cases/controls | 83/131 | 53/110 | 32/74 | 16/29 | ||
| Multivariable OR (95% CI)c | 1 (referent) | 0.74 (0.47–1.17) | 0.71 (0.43–1.20) | 0.88 (0.43–1.77) | 0.2 | |
| Bioavailable 25(OH)D | ||||||
| Low VDBP b | ||||||
| No. of cases/controls | 29/48 | 39/57 | 45/94 | 81/146 | ||
| Multivariable OR (95% CI)c | 1 (referent) | 1.21 (0.64–2.30) | 0.74 (0.39–1.38) | 0.97 (0.55–1.72) | 0.87 | 0.73 |
| High VDBP b | ||||||
| No. of cases/controls | 76/124 | 51/116 | 38/78 | 19/26 | ||
| Multivariable OR (95% CI)c | 1 (referent) | 0.67 (0.41–1.09) | 0.85 (0.50–1.43) | 1.27 (0.63–2.54) | 0.77 | |
| VDBP-bound 25(OH)D | ||||||
| Low VDBP b | ||||||
| No. of cases/controls | 76/106 | 59/91 | 40/81 | 19/67 | ||
| Multivariable OR (95% CI)c | 1 (referent) | 0.88 (0.55–1.39) | 0.69 (0.42–1.13) | 0.41 (0.22–0.76) | 0.007 | 0.33 |
| High VDBP b | ||||||
| No. of cases/controls | 46/67 | 38/80 | 53/92 | 47/105 | ||
| Multivariable OR (95% CI)c | 1 (referent) | 0.67 (0.38–1.19) | 0.82 (0.48–1.42) | 0.59 (0.33–1.06) | 0.14 | |
| VDBP | ||||||
| Low total 25(OH)D b | ||||||
| No. of cases/controls | 71/99 | 56/84 | 47/90 | 46/71 | ||
| Multivariable OR (95% CI)c | 1 (referent) | 1.00 (0.62–1.62) | 0.83 (0.51–1.35) | 0.95 (0.57–1.57) | 0.46 | 0.79 |
| High total 25(OH)D b | ||||||
| No. of cases/controls | 32/73 | 35/88 | 41/82 | 50/102 | ||
| Multivariable OR (95% CI)c | 1 (referent) | 0.95 (0.53–1.72) | 1.12 (0.63–2.00) | 1.12 (0.64–1.96) | 0.50 |
Abbreviations: 25(OH)D, 25-hydroxyvitamin D; CI, confidence interval; OR, odds ratio; VDBP, vitamin D binding protein.
Wald test was used for the product term between stratified variable (binary) and main exposure (continuous).
Low level was defined as ≤median concentration among control participants [279 mg/mL for VDBP, 27.5 ng/mL for total 25(OH)D], and high level otherwise.
Conditional logistic regression adjusted for matching factors (age and time of blood draw), family history of colorectal cancer, multivitamin use, pack-years of smoking (0, 0–9.9, 10–24.9, 25–49.9, ≥50), alcohol consumption (0, 0–5.0, 5.1–15.0, >15 g/d), body mass index (continuous), physical activity (≤5, 5.1–10, 10.1–20, >20 METs), regular aspirin/NSAID use, postmenopausal status and hormone use (premenopausal, never use of postmenopausal hormone, ever use of postmenopausal hormone), calcium intake (in quartiles), and Alternative Healthy Eating Index (in quartiles).