Assessment of disease activity in inflammatory bowel disease; relevance for clinical trials.

In patients with inflammatory bowel disease, assessment of disease activity is important in order to monitor and adjust therapy. In individual patients, disease evaluation is largely based on subjective symptoms. However, for disease evaluation in clinical trials, an objective and reproducible disease activity index is needed. At present, a number of activity indices are available for Crohn's disease and for ulcerative colitis. These indices may be distinguished in more subjective clinical indices, more objective endoscopic and histological indices, and in indices with combinations of both subjective and objective parameters. In the design of a new clinical trial, an appropriate disease activity index should be selected which is based on the patient selection criteria and the aims of the study.