Anti-Saccharomyces cerevisiae antibody (ASCA) positivity is associated with increased risk for early surgery in Crohn's disease

Background: Anti-Saccharomyces cerevisiae antibodies (ASCA) are a specific but only moderately sensitive diagnostic marker for Crohn's disease. We sought to explore the role of ASCA as a prognostic marker for aggressive disease phenotype in Crohn's disease. Aims: To determine the role of ASCA status as a risk factor for early surgery in Crohn's disease. Subjects: We performed a case control study in a cohort of patients, newly diagnosed with Crohn's disease, between 1991 and 1999. All patients were followed for at least three years. Case subjects ( n = 35) included those who had major surgery for Crohn's disease within three years of diagnosis. Controls ( n = 35) included patients matched to cases for age, sex, disease location, and smoking status, and who did not undergo major surgery for Crohn's disease within three years of diagnosis. Methods: Blinded assays were performed on serum for ASCA ( immunoglobulin (Ig) A and IgG). A paired analysis of cases-controls was performed to test for the association between ASCA status and risk of early surgery. Results: ASCA IgA was strongly associated with early surgery (odds ratio (OR) 8.5 (95% confidence interval (CI) 2.0 - 75.9); p = 0.0013). ASCA IgG+ and ASCA IgG+/ IgA+ patients were also at increased risk for early surgery (OR 5.5 ( 95% CI 1.2 - 51.1), p = 0.0265; and OR 5.0 ( 95% CI 1.1 - 46.9), p = 0.0433, respectively). The association between ASCA and early surgery was evident in patients requiring surgery for ileal or ileocolonic disease. Conclusions: Patients with Crohn's disease who are positive for ASCA IgA, IgG, or both, may define a subset of patients with Crohn's disease at increased risk for early surgery.