Retrospective Cohort Study
Copyright ©The Author(s) 2017. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Apr 14, 2017; 23(14): 2539-2544
Published online Apr 14, 2017. doi: 10.3748/wjg.v23.i14.2539
Impact of vitamin D on the hospitalization rate of Crohn's disease patients seen at a tertiary care center
Krishna V R Venkata, Sumant S Arora, Feng-Long Xie, Talha A Malik
Sumant S Arora, Krishna VR Venkata, Department of Internal Medicine, University of Alabama at Birmingham Montgomery Health Center, Montgomery, AL 36116, United States
Feng-Long Xie, Talha A Malik, Department of Medicine-Gastroenterology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
Author contributions: Venkata KVR, Arora SS and Malik TA conceptualized the study hypothesis, design and methodology; Venkata KVR and Arora SS collected data by retrospective chart review; Xie FL performed the statistical analysis; With regard to manuscript write up, Venkata KVR compiled the methods and results section, while Arora SS and Malik TA wrote the introduction and discussion section and all authors proof read for final manuscript edits.
Institutional review board statement: The study was reviewed and approved by the University Of Alabama Office Of Institutional Review Board.
Informed consent statement: Informed consent waiver was given by the IRB as the study is chart review.
Conflict-of-interest statement: The authors declare that they have no conflicts of interest.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Krishna VR Venkata, MD, Department of Internal Medicine, University of Alabama at Birmingham Montgomery Health Center, 2055 E. South Blvd, Suite 200, Montgomery, AL 36116, United States. klakshmi@uabmc.edu
Telephone: +1-713-8150946
Received: November 10, 2016
Peer-review started: November 13, 2016
First decision: December 19, 2016
Revised: March 7, 2017
Accepted: March 15, 2017
Article in press: March 15, 2017
Published online: April 14, 2017
Abstract
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/mL) vs appropriate mean vitamin D level (30-100 ng/mL). 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/mL) 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.

Keywords: Crohn’s disease, Vitamin D, Vitamin D deficiency, Hospitalization rate, Inflammatory bowel disease

Core tip: Growing body of epidemiological evidence supports a key role of vitamin D deficiency not just in inflammatory bowel disease development but also on Crohn’s disease (CD) severity. Our study sought to test the hypothesis that adequate vitamin D levels have a protective role in the clinical course of CD in terms of a decreased likelihood of hospitalization. Our results are clinically important as they suggest potentially worse outcomes in CD patients with low vitamin D levels as reflected by a numerically increased rate of hospitalization in this group.