TABLE 1.
Mean 25(OH)D concentrations by baseline subject characteristics and medication usage1
| Patients, n (%) | 25(OH)D concentration, ng/mL | P value | |
| All | 230 (100) | 21.8 ± 7.5 | |
| Sex | NS | ||
| Women | 107 (46.5) | 22.3 ± 7.4 | |
| Men | 123 (53.5) | 21.4 ± 7.6 | |
| Race | 0.003 | ||
| African American | 12 (5.2) | 15.9 ± 6.3 | |
| Caucasian | 208 (90.4) | 22.4 ± 7.4 | |
| Asian | 10 (4.3) | 17.2 ± 6.7 | |
| Ethnicity | 0.04 | ||
| Hispanic | 6 (2.6) | 15.8 ± 6.9 | |
| Not Hispanic | 224 (97.4) | 22.0 ± 7.5 | |
| Smoking history | NS | ||
| Never | 125 (54.3) | 22.1 ± 7.1 | |
| Former | 86 (37.4) | 21.8 ± 7.8 | |
| Current | 19 (8.3) | 19.6 ± 8.4 | |
| Family history of IBD | NS | ||
| No | 189 (82.2) | 21.7 ± 7.6 | |
| Yes | 41 (17.8) | 22.6 ± 6.8 | |
| Primary sclerosing cholangitis | NS | ||
| No | 216 (93.9) | 21.7 ± 7.5 | |
| Yes | 14 (6.1) | 23.4 ± 7.3 | |
| Disease extent | NS | ||
| Pancolitis | 152 (66.1) | 21.7 ± 6.7 | |
| Left-sided colitis | 60 (26.1) | 21.6 ± 8.5 | |
| Proctosigmoiditis | 18 (7.8) | 23.9 ± 9.6 | |
| BMI, kg/m2 | NS | ||
| <18.5 | 4 (1.8) | 21.3 ± 6.7 | |
| 18.5–25 | 92 (40.9) | 22.0 ± 8.1 | |
| >25–30 | 80 (35.6) | 22.0 ± 7.3 | |
| >30 | 49 (21.8) | 20.9 ± 7.2 | |
| Season of enrollment | NS | ||
| December–February | 62 (27.0) | 20.4 ± 6.8 | |
| March–May | 63 (27.4) | 21.2 ± 8.7 | |
| June–August | 47 (20.4) | 23.1 ± 7.3 | |
| September–November | 58 (25.2) | 22.9 ± 6.7 | |
| Any IBD medication | 0.09 | ||
| No | 16 (7.0) | 18.4 ± 7.3 | |
| Yes | 214 (93.0) | 22.1 ± 7.5 | |
| Oral 5-ASA | 0.03 | ||
| No | 67 (29.1) | 20.2 ± 7.6 | |
| Yes | 163 (70.9) | 22.5 ± 7.4 | |
| Rectal 5-ASA | 0.04 | ||
| No | 184 (80.0) | 21.2 ± 7.0 | |
| Yes | 46 (20.0) | 24.1 ± 8.9 | |
| Corticosteroids | NS | ||
| No | 195 (84.8) | 21.9 ± 7.6 | |
| Yes | 35 (15.2) | 21.5 ± 6.8 | |
| Thiopurine | 0.1 | ||
| No | 171 (74.3) | 21.4 ± 7.6 | |
| Yes | 59 (25.7) | 23.1 ± 7.0 | |
| Anti-TNF-α | NS | ||
| No | 191 (83) | 22.1 ± 7.6 | |
| Yes | 39 (17.0) | 20.3 ± 6.7 | |
| Supplemental vitamin D (any dose) | <0.001 | ||
| No | 98 (42.6) | 18.7 ± 6.6 | |
| Yes | 132 (57.4) | 24.8 ± 7.3 | |
| Supplemental vitamin D dose | <0.001 | ||
| None | 98 (49.0) | 18.7 ± 6.6 | |
| <2000 IU/d | 82 (41.0) | 23.6 ± 6.7 | |
| ≥2000 IU/d | 20 (10.0) | 27.3 ± 9.8 |
1
Mean ± SD 25(OH)D concentrations were compared, and P values were calculated with the use of the Kruskal-Wallis test. Five subjects did not have a height recorded at the time of enrollment to calculate BMI. Thirty subjects reported taking vitamin D supplementation daily, although their dose could not be confirmed. These subjects are reported as taking vitamin D in the analysis of patients taking any dose of supplemental vitamin D dose but are not included in the comparison of 25(OH)D concentration by vitamin D dose. IBD, inflammatory bowel disease; 25(OH)D, 25-hydroxyvitamin D; 5-ASA, 5-aminosalcylate.