Factors associated with 25,OH vitamin D in the SERA case-control study, 2002–07.
| Characteristic | 25,OH Vitamin D, ng/ml, | Unadjusted p | Adjusted p† | |
|---|---|---|---|---|
| N (%) | Mean (SD) | |||
| Sex | ||||
| Male | 68 (30) | 25.04 (8.91) | Referent | Referent |
| Female | 162 (70) | 26.21 (9.51) | 0.37 | 0.31 |
| Taking a supplement containing vitamin D | ||||
| Yes | 157 (68) | 26.51 (8.8) | Referent | Referent |
| No | 73 (32) | 24.47 (10.34) | 0.14 | 0.15 |
| Body mass index (BMI) category (missing for 6 participants) | ||||
| Normal (18.5–24.9) | 100 (43) | 26.89 (9.75) | Referent | Referent |
| Overweight (25–29.9) | 70 (31) | 26.39 (8.88) | 0.57 | 0.52 |
| Obese (30+) | 44 (19) | 21.47 (8.19) | 0.001 | 0.003 |
| Smoking | ||||
| None | 151 (66) | 26.88 (9.41) | Referent | Referent |
| 1–19 pack-yrs | 69 (30) | 24.93 (8.72) | 0.10 | 0.08 |
| 20+ pack-yrs | 10 (4) | 17.17 (8.16) | 0.001 | 0.002 |
| Season of blood draw (%) | ||||
| Warm months (Apr–Sep) | 117 (51) | 27.92 (9.51) | Referent | Referent |
| Cold months (Oct–Mar) | 113 (49) | 23.70 (8.69) | 0.0005 | 0.0002 |
| Race/ethnicity (%) | ||||
| Non-Hispanic white | 200 (87) | 26.31 (9.26) | Referent | Referent |
| Black | 13 (6) | 21.23 (9.91) | 0.06 | 0.05 |
| Hispanic | 13 (6) | 27.00 (7.82) | 0.78 | 0.91 |
| Other | 4 (1) | 14.45 (7.66) | 0.01 | 0.03 |
| Site of recruitment (%) | ||||
| Denver | 185 (80) | 26.06 (9.08) | Referent | Referent |
| Los Angeles | 18 (8) | 29.06 (11.74) | 0.19 | 0.12 |
| Nebraska | 8 (2) | 26.50 (10.65) | 0.9 | 0.37 |
| Seattle | 19 (8) | 19.94 (7.76) | 0.007 | 0.04 |
↵† Adjusted for all other variables, in addition to case status. Vitamin D supplement included individuals taking a multivitamin supplement, vitamin D supplement, or vitamin D supplement with calcium.