OBSERVER VARIATION AND DISCRIMINATORY VALUE OF BIOPSY FEATURES IN INFLAMMATORY BOWEL-DISEASE

If skilled histopathologists disagree over the same biopsy specimen, a t least one must have an incorrect interpretation. Thus, disagreement is associated with, although not the cause of, diagnostic error. The p resent study aimed to determine the magnitude of variation among 10 ob servers with a special interest in gastrointestinal histopathology. Th ey independently interpreted the same biopsy specimens for morphologic al features which may discriminate between patients with Crohn's disea se and ulcerative colitis and normal subjects. Thirty of 41 features h ad agreement measures significantly better than expected by chance (p< 0.05). The range of agreement in the 45 observer pairs over the final diagnosis was 65-76%. There was good agreement in discriminating betwe en normal slides and those showing confirmed inflammatory bowel diseas e. For normal slides, however, the term nonspecific inflammation was o ften applied and without any consistency. In addition, true Crohn's di sease slides were often and consistently thought to be ulcerative coli tis. Having identified 11 important discriminatory morphological featu res, two multiple regression analyses were then carried out to produce a scoring system for inflammatory bowel disease. These results sugges t there is considerable room for improvement in the reliability of col onic biopsy specimen interpretation and that this could probably be ac hieved using more exact definitions of morphological features and dise ases.