Criteria of case definition in Crohn's disease and ulcerative colitis.

The diagnosis of inflammatory bowel disease is usually made on a combination of clinical, radiologic, endoscopic, and histologic grounds. In the differential diagnosis, endoscopy and histologic evaluation of biopsy specimens can help to make a specific diagnosis. Site of disease is important in documentation and can determine drug choice and clinical course. Disease activity indices are important to assess a patient objectively, particularly in multicentre studies. There is poor correlation between disease activity indices and macroscopic and histologic findings. The Severity Activity Index for Crohn's disease has both clinical and laboratory variables and is a valuable tool for the definition of Crohn's disease. An ulcerative colitis activity index that correlates significantly with microscopic and macroscopic scores, using both clinical symptoms and laboratory findings, is proposed.