Anti-Saccharomyces cerevisiae antibodies in Japanese patients with inflammatory bowel disease: diagnostic accuracy and clinical value

The diagnostic accuracy of the determination of anti-Saccharomyces cerevisiae antibodies (ASCA) and its clinical significance in Crohn's disease (CD) have been reported in Western countries, but scarcely reported in Japan, where the dietary habits of people differ markedly from those of Western countries. Th present study was undertaken to examine the diagnostic accuracy and clinical significance of ASCA determination in Japanese patients with CD or ulcerative colitis (UC). Methods: Seventy-five serum samples obtained from 68 patients with CD, 34 serum samples obtained from 30 patients with UC, 35 serum samples from 35 patients with liver cirrhosis, and 31 serum samples from 31 healthy controls were examined. The optical density of each sample was measured by an enzyme-linked immunosorbent assay (ELISA) method to quantify ASCA IgA and IgG. Results: The cutoff level, as determined by discriminant analysis of the data, was 0.1502 for ASCA IgA and 0.156 for ASCA IgG. Of the 68 patients with CD, 31 (45.6%) were ASCA-positive, and of the 30 patients with UC, 4 (13.3%) were ASCA-positive according to these cutoff levels. The sensitivity and specificity of ASCA determination for the differential diagnosis of CD from UC were 45.6% and 86.7%, respectively. When the relationship between ASCA and the clinical features of CD was analyzed, ASCA positivity was found to be correlated with duration of illness. Conclusions: The specificity of ASCA was high; however, the sensitivity was not. ASCA titers were generally low in the Japanese population examined. It would be desirable to determine cutoff levels for ASCA tailored to the Japanese people for the diagnosis of inflammatory bowel disease.