Development of a Crohn's Disease Activity Index

Needing a single index of degree of illness in Crohn's disease, the National Cooperative Crohn's Disease Study group collected data prospectively from 187 visits of 112 patients with Crohn's disease of the small bowel, colon, or both.Information on 18 predictor variables was gathered at each visit.In addition, the attending physician rated his over-all evaluation of how well the patient was doing and compared the patient's status with that at the previous visit.A multiple regression computer program was utilized to derive an equation for prediction of the physician's over-all ratings from a subset of the predictor variables fulfilling a combination of constraints.This equation, numerically simplified and utilizing eight selected variables, is the Crohn's Disease Activity Index .Index values of 150 and below are associated with quiescent disease; values above that indicate active disease, and values above 450 are seen with extremely severe disease.Crohn's disease is a chronic, destructive, inflammatory disease of the intestines of unknown cause, affecting both colon and small bowel, and often leading to severe disability and sometimes death.It is a national health problem, for there are now about 5 new cases per year per hundred thousand people l and expensive hospitalizations are frequently necessary.Its course is characterized by spontaneous exacerbations and remissions which make response to therapy difficult to evaluate.Uncontrolled studies and anecdotal evidence from many clinicians and medical centers report a favorable response of Crohn's disease to several different forms of medical therapy.Yet, the efficacy of each of these forms of therapy has been questioned by responsible and knowledgeable clinicians.Therefore, in 1970, a group of gastroenterologists and others interested in clinical trials met to plan a controlled trial of the relative efficacy of several such treatments, including placebo.Critically important to the design of the trial was a method of assessing the response or lack of response of the disease to the treatment regimen.A major component of the assessment method is quantification of what might be called "activity" of the disease in each patient