Abstract
Background
Vitamin D deficiency has been reported as highly prevalent among patients with inflammatory bowel disease (IBD) and current studies have demonstrated an association between low vitamin D status and an increased risk of clinically active disease, mucosal inflammation and clinical relapse. The aim of our study was to conduct a systematic review and meta-analysis exploring the effect of vitamin D supplementation in clinical and biochemical disease activity scores and relapse rate in patients with IBD.
Methods
We performed a search of major electronic databases (MEDLINE, EMBASE, Cochrane Library) and sources for grey literature (GreyNet international, Google Scholar, Web of Science) from inception to October 2019. Our search strategy was limited to the English and Spanish language. The results were supplemented by a manual search of the bibliographies of the shortlisted review and original study articles. Inclusion criteria: Adults (over 18 years old) with IBD (ulcerative colitis or Crohn’s disease); interventional (RCTs or non-RCTs) or observational studies; studies assessed the effect of vitamin D supplementation on disease activity scores and relapse rate. Exclusion criteria: Reviews, case reports, editorial, comment, letters; duplicates studies; insufficient data or unable to calculate outcome measures with available data. Mean difference was considered as the effect measure with 95% confidence interval (95% CI) and two sided P values. For relapse rate outcome, unadjusted OR were calculated using dichotomous data (events vs. total). Heterogeneity was assessed using χ2 test and I2 statistic. Review Manager software v.5.3 was used.
Results
A meta-analysis of five studies (n = 253) showed a lower relapse rate in vitamin D supplementation group compared with control group (OR: 0.33, 95% CI 0.18–0.61, p = 0.0004, I2: 0%) (Figure 1). Harvey Bradshaw Index improved by 1.52 points (95% CI: 0.14–2.90, p = 0.03, I2 51%) in vitamin D group compared with the score at baseline and C-reactive protein levels decreased compared with the levels at baseline (mean difference: 3.70 mg/l, 95% CI 0.10–7.29, p = 0.04, I2 0%) (Figures 2 and 3). Even though other studies reported different clinical remission tools such as SCCAI or CDAI, it was not possible to pool the results due to insufficient data to conduct a meta-analysis.
Conclusion
Our systematic review and meta-analysis provides evidence that vitamin D supplementation can improve clinical outcomes and reduce relapse rate in patients with IBD.
Managing vitamin D deficiency in inflammatory bowel disease