SEROLOGICAL MARKERS TO DIFFERENTIATE BETWEEN ULCERATIVE-COLITIS AND CROHNS-DISEASE

Aim-To assess prospectively the value of three serological tests for d ifferentiating between ulcerative colitis and Crohn's disease, used ei ther alone or combined. Methods-Coded serum samples from 63 patients w ith ulcerative colitis and 67 patients with Crohn's disease were analy sed. Detection assays for the presence of perinuclear antineutrophil c ytoplasmic antibodies (pANCA), serum agglutinating antibodies to anaer obic coccoid rods, and specific IgG antibodies against a Kd-45/48 immu nological crossreactive mycobacterial antigen complex (ImCrAC) were st udied. Sensitivity, specificity, pre- and post-test probabilities, lik elihood ratios, and predictive values of each of these serological tes ts were determined. Results-The sensitivity and specificity of the pAN CA test for the diagnosis of ulcerative colitis were 61 and 79%, respe ctively. The serum agglutination test for anaerobic coccoid rods had a sensitivity of 42% and a specificity of 89% for a diagnosis of Crohn' s disease. The sensitivity of specific IgG antibodies against Kd-45/48 ImCrAC in diagnosing Crohn's disease was 70% and specificity 60%. Alt hough 100% specificity was achieved by combining all three tests in a small group of patients with Crohn's disease (n=20), combining two or more tests had no additive clinical value. No correlation was found be tween the presence of any one of these antibodies and disease activity , duration, or localisation of disease. Surgery or medical treatment d id not influence the presence of antibodies or the antibody titre. Con clusions-The value of these tests in the differential diagnosis betwee n ulcerative colitis and Crohn's disease is limited, but the high pred ictive values and specificities of different tests for both diseases s uggest that these tests may be of help in studying disease heterogenei ty and in defining different subgroups of patients with different path ogenesis.