Table 2.
Odds ratios (ORs) and 95% confidence intervals (CIs) of prostate cancer by season- and batch-specific quartiles of plasma 25(OH)D
| Outcome | Quartile of plasma 25(OH)D |
Ptrend* | |||||||
| Q1 |
Q2 |
Q3 |
Q4 |
||||||
| No. of case patients/No. of control subjects | OR (95% CI) | No. of case patients/No. of control subjects | OR (95% CI) | No. of case patients/No. of control subjects | OR (95% CI) | No. of case patients/No. of control subjects | OR (95% CI) | ||
| Lethal prostate cancer | |||||||||
| Model 1† | 41/325 | 1.00 (referent) | 33/336 | 0.77 (0.47 to 1.28) | 21/334 | 0.50 (0.28 to 0.88) | 19/329 | 0.43 (0.24 to 0.76) | .001 |
| Model 2‡ | 41/325 | 1.00 (referent) | 33/336 | 0.78 (0.47 to 1.30) | 21/334 | 0.50 (0.28 to 0.88) | 19/329 | 0.44 (0.24 to 0.79) | .002 |
| Overall prostate cancer | |||||||||
| Model 1 | 310/325 | 1.00 (referent) | 298/336 | 0.93 (0.75 to 1.17) | 319/334 | 0.98 (0.78 to 1.22) | 333/329 | 1.05 (0.84 to 1.32) | .57 |
| Model 2 | 310/325 | 1.00 (referent) | 298/336 | 0.93 (0.74 to 1.17) | 319/334 | 0.99 (0.79 to 1.24) | 333/329 | 1.07 (0.86 to 1.34) | .45 |
| Advanced stage at diagnosis | |||||||||
| Model 1 | 51/325 | 1.00 (referent) | 43/336 | 0.88 (0.57 to 1.38) | 32/334 | 0.61 (0.38 to 0.97) | 40/329 | 0.78 (0.50 to 1.23) | .13 |
| Model 2 | 51/325 | 1.00 (referent) | 43/336 | 0.96 (0.61 to 1.52) | 32/334 | 0.63 (0.39 to 1.03) | 40/329 | 0.85 (0.53 to 1.35) | .22 |
| High-grade prostate cancer | |||||||||
| Model 1 | 69/325 | 1.00 (referent) | 55/336 | 0.79 (0.53 to 1.17) | 51/334 | 0.71 (0.48 to 1.05) | 64/329 | 0.92 (0.63 to 1.35) | .56 |
| Model 2 | 69/325 | 1.00 (referent) | 55/336 | 0.81 (0.54 to 1.21) | 51/334 | 0.75 (0.50 to 1.13) | 64/329 | 0.99 (0.67 to 1.46) | .87 |
P values for trend were calculated using unconditional logistic regression using an ordinal variable with values of 1–4 corresponding to the quartile of plasma 25(OH)D and were two-sided.
Model 1: adjusted for age at blood collection (year), prostate-specific antigen test before blood collection (yes or no), year of blood collection, timing of blood collection (midnight to 9 AM, 9 AM to before noon, noon to before 4 PM, 4 PM to before midnight), batch (blood collection [1993–1995]–1996, 1996–1998, 1998–2000, 2000–2004), season (winter, spring, summer, fall), and follow-up time.
Model 2: model 1 + prostate-specific antigen screening frequency (% of all possible recorded tests).