Clinical utility of serological markers in inflammatory bowel disease.

BACKGROUND/AIMS: The role of perinuclear antineutrophil cytoplasmic antibodies (pANCA) and anti-Saccharomyces cerevisiae antibodies (ASCA) assessment in inflammatory bowel disease (IBD) diagnosis and differentiating is still imprecise and controversial. The aim of the study was to determine the accuracy of pANCA and ASCA in patients with IBD subgroups. METHODOLOGY: The study was performed in 125 patients: 71 patients with ulcerative colitis (UC), 31 with Crohn's disease (CD) and 23 with indeterminate Colitis (IC). Control group consists of 45 patients with functional intestinal disorders. pANCA and ASCA (IgA and IgG) were measured with ELISA, using commercial antibody panel. RESULTS: In UC patients the prevalence of pANCA was 68%, which was significantly higher than in CD-29%. ASCA were found significantly more often in CD-80.6% than in UC patients-26.8%. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of pANCA for UC diagnosis was 68%, 84%, 75% and 78%; and ASCA for CD: 81%, 78%, 45,5% and 95%, respectively. The combined use of these two markers gave changes in diagnostic accuracy: pANCA+/ASCA- in UC: 42%, 100%, 100% and 43%, and for pANCA-/ASCA+ in CD: 52%, 98.6% 94% and 82%, respectively. CONCLUSIONS: The specificity of these combined markers tends to be higher than sensitivity, what made them more useful in the differentiation of the IBD subtypes rather than population screening. The characteristic IC serotype pANCA(-)ASCA(-) leads to further controversies about origin of this IBD subtype.