The importance of diagnostic accuracy in colonic inflammatory bowel disease

OBJECTIVE: Crohn's disease (CD) and ulcerative colitis (UC) may both affect the colon. However, in approximately 10-20% of these cases, it is impossib le to distinguish between these two entities either clinically or histologi cally, and a diagnosis of indeterminate colitis (IC) is made. Correct diagn osis is important because surgical treatment and long-term prognosis differ for UC and CD. The purpose of this study was to determine the extent of in terobserver agreement among board-certified pathologists and a specialist g astrointestinal (GI) pathologist regarding the histological diagnosis of co lonic inflammatory bowel disease (IBD). METHODS: A total of 24 university medical center pathologists from eight in stitutions evaluated 84 colectomy specimens and 35 sets of biopsy specimens from 1 19 consecutive patients with colonic IBD. A specialist GI pathologi st subsequently reviewed all cases without knowledge of clinical data and-p rior diagnosis. RESULTS: The GI pathologist's diagnoses differed from the initial diagnoses in 45% of surgical specimens and 54% of biopsy specimens. Of 70 cases init ially diagnosed as UC, 30 (43%) were changed to CD or IC, whereas 4 of 23 c ases (17%) initially diagnosed as CD were changed to UC or IC. The kappa co efficient for the overall agreement of initial diag noses with the speciali st GI pathologist's diagnoses was -0.01(p = 0.98). CONCLUSIONS: There is significant interobserver variation in the histologic al diagnosis of colonic LED. This may have a profound effect on clinical pa tient care and, especially, on the choice of operation. More accurate diagn ostic criteria are needed to facilitate patient care and to optimize treatm ent outcome. (C) 2000 by Am. Cell. of Gastroenterology).