Uses and limitations of the Crohn's disease activity index.

The Crohn's Disease Activity Index (CDAI) proposed by a US Working Party was used in 39 Crohn's patients attending a combined medical and surgical gastrointestinal unit as out and inpatients. It proved easy to use and a range of values from 0 to 294 was obtained. Analysis of the contribution of its 8 components suggested a very considerable emphasis on well-being and haematocrit. No correlation with location of disease was found but there was a correlation with hospital admission and subjective assessment. Low values were found in several patients who, although known to have extensive disease were well on medical therapy. Therefore the Index measured the activity not the extent or presence of Crohn's disease. It is a very useful measure for clinical trials but in no way could replace full clinical assessment.