PANCA AND ASCA - SCREENING TOOLS FOR INFLAMMATORY BOWEL DISEASE?

Abstract

Purpose: Serological markers have recently been developed for the characterization of inflammatory bowel disease (IBD). Perinuclear Anti-Neutrophil Cytoplasmic Antibody (pANCA) is generally associated with Ulcerative Colitis (UC), while Crohn's Disease (CD) is typically associated with Anti-Saccharomyces cerevisiae Antibody (ASCA). Overlapping serologies for different disease states have also been recognized. The role and reliability of serological markers as screening tools remains controversial. The ideal screening tool would minimize invasive tests and avoid delays in diagnosis. AIM To define the usefulness of serological markers for the diagnosis and characterization of IBD at our Children's Hospital. Methods: We conducted a retrospective chart review over a 5 year period. To be included in the study patients must have: 1) been <18 years old, 2) presented with symptoms suggestive of IBD, 3) undergone colonoscopy and biopsy, and 4) had IBD serological maker testing (pANCA, ASCA IgA, and ASCA IgG) by Prometheus Laboratories Inc. (San Diego, CA). The diagnosis of CD, UC, or Inderterminate Colitis (IC) was clinically established by a combination of historical, endoscopic, histological, and/or radiographic criteria. False negative results were defined as patients with a clinical diagnosis of IBD, but did not have any positive serologic marker. False positive results were defined as patients who did not have endoscopic and histologic findings suggestive of IBD but who had any serological marker positive. Results: Out of 148 patients who met inclusion criteria, 73 patients had clinical IBD. Twenty nine patients were diagnosed with CD, 22 patients were diagnosed with UC, and 22 patients were diagnosed with IC. In CD patients, 34% were ASCA positive, 28% were ANCA positive, and 38% were negative. In UC patients, 73% were ANCA positive, 18% were ASCA positive, and 23% were negative. In IC patients, 18% were ANCA positive, 32% were ASCA positive, and 54% were negative. Twenty eight of 73 (38%) patients with clinically diagnosed IBD had all serological markers negative (false negative). Of the 75 patients who did not have clinical IBD, 11 (15%) had positive serology (7% ANCA, 9% ASCA) (false positive). Conclusions: 1. Our findings suggest there are a significant number of false negative and positive results with ASCA and pANCA markers for IBD. 2. IBD serological markers should be applied with caution as a screening tool in pediatric patients with gastrointestinal symptoms to rule out IBD.