Diagnostic Value of ASCA and Atypical p-ANCA in Differential Diagnosis of Inflammatory Bowel Disease

BACKGROUND Worldwide, the incidence of inflammatory bowel disease (IBD) is increasing. This study aims to evaluate the diagnostic value of two serological markers, atypical perinuclear anti-neutrophil cytoplasmic antibodies (atypical-P-ANCA) and anti-Saccharomyces cerevisiae antibodies (ASCA), with the intent to determinetheir relationship to ulcerative colitis (UC) and Crohn’s disease (CD), in addition to the location and extent of bowel involvement. METHODS There were 97 patients enrolled in this study, 72 diagnosed with UC and 25 with CD.The control group consisted of 40 healthy individuals. ASCA was determined by enzyme-linked immunosorbent assay (ELISA) and atypical-P-ANCA by indirect immunofluorescence assay (IIF). For data analyses, we used the chi-square and independent t-tests. Significance was considered to be p<0.05. RESULTS For CD, the sensitivityof ASCA was 16% and its specificity was 97%.ASCA had a specifity of 90% in UC patients. The atypical P-ANCA test had a sensitivity of 44% and specificity of 86% for UC. The positive predictive value (PPV) for atypical P-ANCA in UC patients was 78% and for the negative predictive value (NPV), it was 58%.There was no correlation between ASCA and atypical P-ANCA results and the location of gastrointestinal (GI) involvement in CD (p=0.61) and UC (p=0.28) patients. CONCLUSION According to the results, ASCA and atypical P-ANCA markers are not useful for IBD screening. Our study suggests that atypical P-ANCA is a useful parameter to differentiate UC from CD. However, ASCA is of limited value for screening and differentiating UC from CD.