title: The Relevance of Vitamin D and Antinuclear Antibodies in Patients with Inflammatory Bowel Disease Under Anti-TNF Treatment: A Prospective Study.
abstract: 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.
authors.affiliation: Gastroenterology Department, Faculty of Medicine, Hospital de São João, Porto, Portugal.
authors.forename: João
authors.initials: J
authors.lastname: Santos-Antunes
authors.forename: Amadeu Corte-Real
authors.initials: AC
authors.lastname: Nunes
authors.forename: Susana
authors.initials: S
authors.lastname: Lopes
authors.forename: Guilherme
authors.initials: G
authors.lastname: Macedo
mesh_terms: D000293:Adolescent; D000328:Adult; D000974:Antibodies, Antinuclear / Q000097:blood* / Q000276:immunology; D005260:Female; D005500:Follow-Up Studies; D005765:Gastrointestinal Agents / Q000627:therapeutic use; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000097:blood / Q000150:complications / Q000188:drug therapy* / Q000276:immunology; D000069285:Infliximab / Q000627:therapeutic use*; D008297:Male; D011379:Prognosis; D011446:Prospective Studies; D012307:Risk Factors; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors*; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000175:diagnosis* / Q000209:etiology; D055815:Young Adult
chemical_list: D000974:Antibodies, Antinuclear; D005765:Gastrointestinal Agents; D014409:Tumor Necrosis Factor-alpha; D014807:Vitamin D; C104450:25-hydroxyvitamin D; D000069285:Infliximab