Diagnostic value and clinical significance of serological markers in Tunisian patients with inflammatory bowel diseases

The aim of our study was to evaluate the sensitivity, specificity and predictive values of isolated and combined ASCA and NANA assays in Tunisian inflammatory bowel diseases patients and to assess whether their presence is associated with particular clinical features of the disease. Methods: 128 patients (39 with ulcerative colitis, 25 with Crohn disease, and 64 healthy subjects) were enrolled in the study. ASCA and NANA were performed by ELISA and indirect immuno-fluorescence, respectively. Sensitivity, specificity, PPV and NPV of NANA for UC was: 56.4%, 88%, 88% and 56.4%; and ASCA for CD were: 56%, 82.1%, 54.5% and 75.6%, respectively. The combined use of these two markers modified diagnostic accuracy: NANA+/ASCA- in UC 53.8%, 88%, 87.5% and 55% and for NANA/ASCA+ in CD 52%, 94.9%, 86.7% and 75.5%. No significant association was found between the presence of a specific serological marker and patients' clinical features. In conclusion, 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.