Table 4.
Observational Association of Baseline Serum 25-Hydroxyvitamin D Level and Dietary Calcium Intake with Risk of Colorectal Adenoma.
| Quartile of Level or Intake* | Baseline Serum 25-Hydroxyvitamin D Level† | Baseline Dietary Calcium Intake‡ | ||||
|---|---|---|---|---|---|---|
| No. of Patients/ Total No. (%) |
Adjusted Risk Ratio (95% CI)§ |
Adjusted Risk Ratio per 10 ng/ml (95% CI) |
No. of Patients/ Total No. (%) |
Adjusted Risk Ratio (95% CI)¶ |
Adjusted Risk Ratio per 200 mg (95% CI) |
|
|
Participants with one or more adenomas |
0.98 (0.90–1.07) |
0.99 (0.93–1.04) |
||||
| Quartile 1 | 108/256 (42.2) | Reference | 89/179 (49.7) | Reference | ||
| Quartile 2 | 115/271 (42.4) | 1.02 (0.83–1.25) |
94/170 (55.3) | 1.17 (0.95–1.46) |
||
| Quartile 3 | 117/257 (45.5) | 1.06 (0.86–1.30) |
69/170 (40.6) | 0.85 (0.65–1.08) |
||
| Quartile 4 | 102/251 (40.6) | 0.98 (0.79–1.21) |
84/184 (45.7) | 0.95 (0.75–1.19) |
||
|
Participants with one or more advanced adenomas║ |
0.91 (0.71–1.16) |
0.94 (0.80–1.10) |
||||
| Quartile 1 | 25/257 (9.7) | Reference | 21/176 (11.9) | Reference | ||
| Quartile 2 | 28/270 (10.4) | 1.11 (0.66–1.88) |
15/176 (8.5) | 0.72 (0.38–1.36) |
||
| Quartile 3 | 21/263 (8.0) | 0.83 (0.47–1.46) |
19/170 (11.2) | 0.96 (0.52–1.75) |
||
| Quartile 4 | 24/252 (9.5) | 1.06 (0.61–1.83) |
18/185 (9.7) | 0.82 (0.44–1.53) |
||
For 25-hydroxyvitamin D, quartiles of seasonally adjusted values were as follows: quartile 1, ≤18.411 IU; quartile 2, 18.412 to 23.178 IU; quartile 3, 23.179 to 29.326 IU; and quartile 4, ≥29.327 IU. For calcium intake, the quartiles were as follows: quartile 1, up to 435.7 mg; quartile 2, 437.8 to 596.7 mg; quartile 3, 596.8 to 831.2 mg; and quartile 4, ≥831.3 mg.
The analysis was restricted to participants who did not receive study vitamin D supplementation; risk ratios were adjusted for age, clinical center, anticipated surveillance interval (3 or 5 years), a three-level variable for sex and type of randomization (male, female and two-group randomization, female and full factorial randomization), number of baseline adenomas (one, two, or three or more), and calcium treatment assignment (participants who underwent two-group randomization are grouped with participants who underwent full factorial randomization and received calcium).
The analysis was restricted to participants who underwent full factorial randomization and did not receive study calcium supplementation; risk ratios were adjusted for age, clinical center, anticipated surveillance interval (3 or 5 years), sex, number of baseline adenomas (one, two, or three or more), and vitamin D treatment assignment; because of sparse data for advanced adenomas, clinical centers are grouped geographically into southeast (Georgia, North Carolina, South Carolina, and Puerto Rico), north (Ohio, New Hampshire, Iowa, and Minnesota), and west (Colorado, Texas, and California).
The P value for trend for adenomas was 0.86, and the P value for trend for advanced adenomas was 0.95.
The P value for trend for adenomas was 0.33, and the P value for trend for advanced adenomas was 0.99.
Denominators differ between adenomas and advanced adenomas because of missing data on lesion size and an assumption that small lesions (<6 mm) with missing pathological data are not advanced adenomas (see the Supplementary Appendix).