Investigating the relationship between vitamin D levels and immune-mediated colitis

Background The aim of this study was to evaluate the potential association between serum vitamin D levels and the incidence and severity of immune-mediated colitis (IMC), and to explore the potential role of vitamin D supplementation as a preventative or therapeutic intervention. Methods This was a single-center study in which we retrospectively reviewed patients who received immune checkpoint inhibitor (ICI) treatment, had serum vitamin D levels measured within 6 months before or after starting treatment, and subsequently developed IMC. Results A total of 179 patients were included in the study. Patients were stratified by serum vitamin D levels: 121 (67.6%) had levels ≤40 ng/mL, and 58 (32.4%) had levels >40 ng/mL. Individuals with vitamin D levels ≤40 ng/mL had more severe diarrhea (65.0%) and severe colitis (48.0%), both defined as common terminology criteria for adverse events grade ≥2, compared to those with vitamin D levels >40 ng/mL (45.6% and 28.6%, respectively; P=0.022 and P=0.034). Univariate analysis revealed that patients receiving vitamin D during ICI therapy had ~1.9 times higher odds of requiring steroid treatment (odds ratio [OR] 1.899, 95% confidence interval [CI] 1.0338-3.474; P=0.038). Patients with grade ≥2 diarrhea had 11 times higher odds of requiring steroids (OR 11.11, 95%CI 5.35-22.73; P<0.001). Patients with colitis grade ≥2 had 3 times higher odds of steroid use (OR 3.08, 95%CI 1.54-6.13; P=0.001). Conclusions This study suggests that there is a relationship between serum vitamin D levels and IMC. Vitamin D deficiency in those with IMC was associated with more severe disease, and those with more severe disease were more likely to require steroid therapy.