Circulating 25-hydroxyvitamin D concentration can predict bowel resection risk among individuals with inflammatory bowel disease in a longitudinal cohort with 13 years of follow-up.

BACKGROUND: Although the beneficial properties of vitamin D in anti-inflammation and immunity-modulation are promising in the management of inflammatory bowel disease (IBD), data were limited for the critical IBD prognosis. The association between serum vitamin D levels and the risk of bowel resection in individuals with IBD remains largely unknown.

MATERIALS AND METHODS: We performed a longitudinal cohort study among 5474 individuals with IBD in the UK Biobank. Serum 25-hydroxyvitamin D [25(OH)D] was measured using direct competitive chemiluminescent immunoassay. Bowel resection events were ascertained via national inpatient data. Multivariable-adjusted Cox proportional hazard regression was used to examine the association between serum 25(OH)D and bowel resection risk, presented with hazard ratios (HRs) and 95% confidence intervals (CIs). Restricted cubic spline (RCS) was used to evaluate dose-response associations.

RESULTS: During a mean follow-up of 13.1 years, we documented 513 incident bowel resection cases. Compared to participants with vitamin D deficiency, non-deficient participants showed a significantly reduced bowel resection risk in IBD (HR 0.72, 95% CI 0.59-0.87, P=0.001), Crohn's disease (CD, HR 0.74, 95% CI 0.56-0.98, P=0.038), and ulcerative colitis (UC, HR 0.73, 95% CI 0.57-0.95, P=0.020). When comparing extreme quintiles of 25(OH)D level, participants with IBD showed a 34% reduced risk of bowel resection (95% CI 11%-51%, P=0.007) and participants with UC showed a 46% reduced risk (95% CI 19%-64%, P=0.003), while this association was not significant in CD (HR 0.93, 95% CI 0.59-1.45, P=0.740). Linear dose-response associations were observed using the RCS curve (all P-nonlinearity>0.05).

CONCLUSION: Increased serum level of 25(OH)D is independently associated with reduced bowel resection risk in IBD. This association was significant in UC but may not be stable in CD. Vitamin D deficiency is a risk factor for bowel resection in individuals with IBD, and may be an effective metric in predicting and risk-screening surgical events.