The Relevance of Vitamin D and Antinuclear Antibodies in Patients with Inflammatory Bowel Disease Under Anti-TNF Treatment: A Prospective Study.

BACKGROUND: The importance of vitamin D in inflammatory bowel disease (IBD) has been analyzed in former studies, namely concerning the severity of the disease and the efficacy of anti-tumor necrosis factor (TNF) medications. In several inflammatory conditions, biologics have been associated with an autoimmune response with formation of antinuclear antibodies (ANA). In addition, an inverse relationship between vitamin D levels and ANA has been documented. We aimed to evaluate the clinical importance of the link between vitamin D, ANA, and anti-TNF in patients with IBD. METHODS: Prospective study including patients with IBD with indication to start anti-TNF, between 2009 and 2014. Deficiency and extreme deficiency of vitamin D were defined as levels of 25-hydroxyvitamin D below 20 and 4 ng/mL, respectively. ANA titers were considered positive if higher or equal to 1/100. RESULTS: Among 68 patients (56 with Crohn's Disease, 12 with ulcerative colitis), vitamin D deficiency was detected in 93%. Pretreatment positivity for ANA was related to higher failure rates of anti-TNF treatment (P = 0.008). Pretreatment positivity for ANA and extreme vitamin D deficiency were significant risk factors for adverse events associated with anti-TNF therapy. A significant link was found between extreme deficiency of vitamin D and the presence of ANA. CONCLUSIONS: Our study highlights the association between vitamin D deficiency and pretreatment positivity for ANA with the risk for anti-TNF failure and adverse events, and the inverse relationship between vitamin D levels and ANA. Due to the high prevalence of vitamin D deficiency in IBD and the immune-mediated nature of the disease, these elements should be evaluated before starting biologics.