Low vitamin D serum levels during periods of clinical remission increase the risk of relapse in patients with ulcerative colitis (UC), a new study shows.
The results indicate that patients with UC should be closely monitored for levels of vitamin D, and support the need for supplements in maintenance therapy if necessary.
The study, “Low Serum Vitamin D During Remission Increases Risk of Clinical Relapse in Patients With Ulcerative Colitis,” was published in the journal Clinical Gastroenterology and Hepatology.
“We showed that vitamin D levels are associated with baseline endoscopic and histologic inflammation severity during clinical remission, and are associated independently with the longitudinal risk of clinical relapse,” John Gubatan, MD, and colleagues from the Department of Medicine, division of gastroenterology and hepatology at Beth Israel Deaconess and Harvard Medical School in Boston, wrote, according to a news release.
“These results suggest that vitamin D status is linked not only to current disease severity, but also has an impact on future risk of clinical relapse,” he added.
Ulcerative colitis (UC) and Crohn’s disease (CD) are inflammatory bowel diseases (IBDs) that are chronic disorders of the gastrointestinal tract, believed to result from a complex interplay between genetic, environmental, immune, and microbial factors.
Vitamin D status has been implicated with disease severity, but the clinical significance of low vitamin D levels among UC patients in clinical remission has been unclear.
Gubatan and colleagues conducted a prospective analysis of 70 patients with UC in clinical remission (those with a score of 2 or less on the Simple Clinical Colitis Activity Index). All patients were recruited after a surveillance colonoscopy at the IBD Center at Beth Israel Deaconess.
During the colonoscopy procedures, serum samples were collected, and the levels of 25-hydroxy-vitamin D were measured using a specific assay. All patients were then followed for 12 months to assess the rate of clinical relapse. Sixty percent of patients reported taking vitamin D supplements.
The researchers found that the mean baseline vitamin D level was lower among patients who relapsed during the 12 months of follow-up — 29.5 ng/mL among patients who relapsed compared to 50.3 ng/mL among those who did not.
A level of vitamin D during disease remission of less than 35 ng/mL was associated with a risk of clinical relapse over 12 months, as 20% of patients with vitamin D levels of or less than 35 ng/mL at baseline had relapsed, while 9% of patients with a vitamin D level that exceeded that value did not relapse. In addition, a low level of vitamin D at baseline was associated with increased endoscopic and histologic inflammation.
The vitamin D serum level of 35 ng/mL or less had sensitivity of 70 percent and a specificity of 74 percent in predicting risk of clinical relapse.
“Our study provides evidence that low vitamin D levels … correlate with endoscopic and histologic inflammation and are associated with an increased risk of subsequent clinical relapse during periods of clinical remission,” researchers concluded.
“Vitamin D is an affordable, accessible, and relatively nontoxic supplement that may have protective effects in the maintenance of clinical remission in patients with ulcerative colitis,” they wrote. “Clinical trials of vitamin D therapy to obtain vitamin D levels above this threshold should be considered to definitively establish its impact on ulcerative colitis outcomes.”
While the findings from this study were robust, “more unknowns remain unknown that unmask residual uncertainties,” Stephen B. Hanauer, MD, of the Department of Medicine and the Digestive Health Center at Northwestern University Feinberg School of Medicine in Chicago, wrote in an editorial related to the study.
One of the major strengths of this study was the fact that researchers included the 35 ng/mL vitamin D cut-off mark, which falls between the normal range (20-40 ng/mL), as well as the “confidence intervals regarding the risk of relapse at lower or higher vitamin D levels, in which there does not appear to be a dose-response in the odds ratios according to levels,” he wrote, also highlighting the need for more prospective trials.