The between-run CV was 4.6% at 53 nmol/L and 9.9% at 28 nmol/L. We defined 25OHD3

levels <50 nmol/L (20 ng/mL) as being vitamin D deficient. Statistical analyses Statistical analyses were performed using SPSS 17.0 (SPSS Inc., Chicago, IL, USA). For univariate comparison, 25OHD levels were stratified in two groups C188-9 ic50 (vitamin D deficiency, <50 nmol/L, and adequate vitamin D status, ≥50 nmol/L). Univariate statistical analyses were performed by using a parametric test (unpaired t test) when a normal distribution was present and, when in order, a non-parametric test (Mann–Whitney U) to assess significant associations between the stated continuous determinants and the various groups (CD patients vs. UC patients, and vitamin D deficiency vs. adequacy). Categorical determinants were analysed by using Pearson’s Chi-square test (or Fisher’s exact test when expected frequencies were low). Furthermore, quartiles according the 25OHD levels were stratified and assessed using a one-way ANOVA test with a Bonferroni post hoc test as parametric test when a normal distribution was present, and a non-parametric test (Kruskal–Wallis test) when in order to assess significant associations between the stated determinants

and 25OHD quartiles. Mean differences between 25OHD levels in summer and winter were calculated with the non-parametric Wilcoxon signed rank test. In order to identify PARP activity independent risk factors of vitamin D deficiency in summer and

winter, a logistic regression model was used with vitamin D deficiency as dependent factor. All p values >0.10 are noted in the tables as NS (non-significant). not All p DMXAA order values between 0.5 and 0.10 are noted in order to identify non-significant trends. All p values <0.05 were considered as statistically significant. Results In this study, 316 patients with a mean age (±SD) of 48.5 ± 14.8 years were included (Table 1). Fifty-seven percent of the included patients were women. Ninety-seven percent of the patients were of Caucasian ethnicity. The main group of IBD patients was diagnosed with UC (59%). The mean duration of IBD (±SD) was 11.0  ± 9.7 years. Table 1 Baseline characteristics and laboratory results of IBD patients   Total CD patients UC patients p valuea n = 316 n = 131 n = 185 Age, years (SD) 48.5 (14.8) 46.5 (14.7) 49.9 (14.8) 0.046 Women, n (%) 181 (57.3) 84 (64.1) 97 (52.4) 0.039 Postmenopausal state, n (% of women) 71 (39.2) 32 (38.1) 39 (40.2) NS Body mass index, kg/m2 (SD) 25.3 (4.5) 25.5 (4.8) 25.1 (4.3) NS Active IBD, n (%) 160 (50.6) 70 (53.4) 90 (48.6) NS Disease duration IBD, years (SD) 11.0 (9.7) 11.1 (10.0) 11.0 (9.6) NS Exacerbation IBD, episodes/year (SD) 2.7 (2.1) 2.8 (2.2) 2.7 (1.9) NS History of >7.5 mg daily corticosteroid usage for at least 6 months, n (%) 92 (29.1) 38 (29.0) 54 (29.2) NS Daily use of oral vitamin D supplementation, n (%) 106 (33.5) 42 (32.1) 64 (34.6) NS Low dietary calcium intake, n (%) 15 (4.8) 6 (4.6) 9 (4.