Association Between Inflammatory Bowel Disease and Vitamin D Deficiency: A Systematic Review and Meta-analysis.
BACKGROUND
Vitamin D plays a role in several immune-mediated diseases, but its association with inflammatory bowel disease (IBD) is unclear. We conducted a systematic review and meta-analysis to assess the association between IBD and vitamin D deficiency.


METHODS
We searched electronic databases from inception to December 2014 for observational studies reporting the presence of vitamin D deficiency (defined as serum 25-hydroxycholecalciferol [25(OH)D] level of ≤20 ng/mL) in IBD patients and having a control group without IBD. Odds ratios (ORs) were combined using a random-effects model. Meta-regression was performed using latitude as a moderator. Study quality was assessed using the Newcastle-Ottawa scale.


RESULTS
Out of 816 citations, 14 eligible studies were identified, comprising 1891 participants (938 IBD cases and 953 controls). Meta-analysis showed that patients with IBD had 64% higher odds of vitamin D deficiency when compared with controls (OR = 1.64; 95% confidence interval, 1.30-2.08; I = 7%; P < 0.0001). Patients with ulcerative colitis had more than double the odds of vitamin D deficiency when compared with normal controls (OR = 2.28; 95% confidence interval, 1.18-4.41; I = 41%; P = 0.01). Latitude did not influence the association between IBD and vitamin D deficiency (P = 0.34). Generalizability of our results might be limited as we summarized unadjusted ORs, because of nonavailability of adjusted ORs in individual studies.


CONCLUSIONS
IBD is significantly associated with having higher odds of vitamin D deficiency. Well-designed randomized controlled trials and longitudinal studies are needed to further explain the role of vitamin D in IBD pathogenesis and its therapy.
*Division of Internal Medicine, Department of Life, Health and Environmental Sciences, San Salvatore Hospital, University of L'Aquila, L'Aquila, Italy; †Division of Gastroenterology and Liver Disease, Case Western Reserve University, Cleveland, Ohio; ‡Division of Dentistry, Department of Life, Health and Environmental Sciences, San Salvatore Hospital, University of L'Aquila, L'Aquila, Italy; and §Digestive Health Institute, University Hospitals Case Medical Center, Cleveland, Ohio.
Rita
R
Del Pinto
Davide
D
Pietropaoli
Apoorva K
AK
Chandar
Claudio
C
Ferri
Fabio
F
Cominelli
D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000453:epidemiology*; D064887:Observational Studies as Topic; D016017:Odds Ratio; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000453:epidemiology*
D014807:Vitamin D; C104450:25-hydroxyvitamin D