Influence of Severe Vitamin D Deficiency on the Clinical Course of Inflammatory Bowel Disease.

BACKGROUND: Previous studies have shown vitamin D status to be associated with disease activity in patients with inflammatory bowel disease (IBD), but its influence on the clinical course of IBD has not been established. AIMS: We aimed to analyze whether the serum 25-hydroxyvitamin D3 [25(OH)D] status is associated with clinical characteristics and affects the risk of surgery in patients with IBD. METHODS: From the IBD registry of the Asan Medical Center, we identified all patients who had at least one 25(OH)D measurement; we then analyzed the association between clinical factors and 25(OH)D status. 25(OH)D was considered borderline deficient, deficient, and severely deficient at levels of < 30, < 20, and < 10 ng/mL, respectively. RESULTS: We included 711 Crohn's disease (CD) and 764 ulcerative colitis (UC) patients who had not undergone surgery before 25(OH)D was measured. Both in CD and in UC patients, reduced 25(OH)D was associated with higher disease activity scores and CRP levels (p < 0.001). Severe 25(OH)D deficiency was associated with ileocolonic disease and complicated behavior in CD (p < 0.05) and was relevant to the disease extent in UC (p < 0.001). Additionally, severe 25(OH)D deficiency was associated with CMV colitis in patients with UC (p < 0.001). In multivariable analysis, severe deficiency of 25(OH)D was an independent risk factor for surgery in both CD (HR 1.93, 95% confidence interval [CI] 1.38-2.70) and UC (HR 2.77, 95% CI 1.14-6.74). CONCLUSION: Severe 25(OH)D deficiency may be a marker of a more aggressive clinical course of IBD.