Impact of vitamin D on the hospitalization rate of Crohn's disease patients seen at a tertiary care center

AIM To study the association between vitamin D level and hospitalization rate in Crohn's disease(CD) patients.METHODS We designed a retrospective cohort study using adult patients(> 19 years) with CD followed for at least one year at our inflammatory bowel disease center. Vitamin D levels were divided into: low mean vitamin D level(< 30 ng/m L) vs appropriate mean vitamin D level(30-100 ng/m L). Generalized Poisson Regression Models(GPR) for Rate Data were used to estimate partially adjusted and fully adjusted incidence rate ratios(IRR) of hospitalization among CD patients. We also examined IRRs for vitamin D level as a continuous variable.RESULTS Of the 880 CD patients, 196 patients with vitamin D level during the observation period were included. Partially adjusted model demonstrated that CD patients with a low mean vitamin D level were almost twice more likely to be admitted(IRR = 1.76, 95%CI: 1.38-2.24) compared to those with an appropriate vitamin D level. The fully adjusted model confirmed this association(IRR = 1.44, 95%CI: 1.11-1.87). Partially adjusted model with vitamin D level as a continuous variable demonstrated,higher mean vitamin D level was associated with a 3% lower likelihood of admission with every unit(ng/m L) rise in mean vitamin D level(IRR = 0.97, 95%CI: 0.96-0.98). The fully adjusted model confirmed this association(IRR = 0.98, 95%CI: 0.97-0.99). CONCLUSION Normal or adequate vitamin D stores may be protective in the clinical course of CD. However, this role needs to be further characterized and understood.