[Anti-neutrophil cytoplasmic antibodies in the diagnosis of ulcerative colitis and Crohn's disease]

Abstract

Background and objective: We assessed the prevalence and diagnostic value of antineutrophil cytoplasmic antibodies (ANCA) with a perinuclear pattern (pANCA) in patients with Crohn's disease (CD) and ulcerative colitis (UC).

Patients and method: pANCA were determined by indirect immunofluorescence and positive results were confirmed by ELISA.

Results: We included 117 patients with CD, 72 with UC and 2 with indeterminate colitis. One CD patient (0.9%) and 6 with UC (8.3%) had a positive pANCA result. Sensitivity, specificity, positive and negative predictive value, and positive and negative likehood ratio of pANCA for a diagnosis of UC (vs CD) were 8%, 99%, 86%, 64%, 8 and 0.9, respectively, thus indicating the need to standardize the methodology. No differences were observed with regard to age, tobacco consumption, localization and extension of UC and need of immunosuppressive agents according to pANCA.

Conclusions: In our setting, the prevalence of pANCA is very low (8%) in UC and exceptional (< 1%) in CD. As a result, pANCA sensitivity for a diagnosis of UC in patients with inflammatory bowel disease is also very low, yet the specificity is very high.