Diagnostic value of anti-Saccharomyces cerevisiae and antineutrophil cytoplasmic autoantibodies in inflammatory bowel disease

OBJECTIVES: Correct diagnosis of inflammatory bowel disease (IBD), especial ly the differentiation between Crohn's disease (CD) and ulcerative colitis (UC), is highly important toward treatment and prognosis. Serological marke rs are noninvasive diagnostic tools that could be of value in differentiati ng CD from UC, in cases of indeterminate colitis, and in the identification of subgroups in IBD. The aim of this study was to evaluate the diagnostic accuracy of perinuclear antineutrophil cytoplasmic (pANCA) and anti-Sacchar omyces cerevisiae antibodies (ASCA) for IBD. METHODS: ASCA and pANCA were studied in a large cohort of consecutive IBD p atients (n = 582: 407 CD, 147 UC, and 28 indeterminate colitis), patients w ith non-IBD diarrheal illnesses (n = 74), and healthy controls (n = 157). A n indirect immunofluorescence technique and a standardized ELISA were perfo rmed for detection of pANCA and ASCA, respectively. RESULTS: prevalence of ASCA and pANCA was high in CD patients (59.7%) and U C (49.7%;) patients, respectively. Positivity for both markers was signific antly lower in healthy and non-IBD controls. Accuracy data (sensitivity, sp ecificity, PPV, and NPV, respectively) for differentiating IBD from control s are as follows: ASCA(+): 60% (243/407), 91% (345/378), 88% (243/276), and 68% (345/509); pANCA(+): 50% (73/147), 95% (605/638), 69% (73/106), and 89 % (605/679); ASCA(+)/pANCA(-): 56% (229/407), 94% (355/378), 91% (229/252), and 67% (355/533); and pANCA(+)/ASCA(-): 44% (65/147), 97% (620/638), 78% (65/83), and 88% (620/702). CONCLUSIONS: Specificity of serological markers for LED is high, but low se nsitivity makes them less useful as diagnostic tests. The combination of te sts is probably more powerful, although, clinical subgroups still need to b e defined. The usefulness of these markers in indeterminate colitis needs t o be studied prospectively. (C) 2001 by Am. Cell. of Gastroenterology.