Comparison between prospective and retrospective evaluation of Crohn's disease activity index

The Crohn's disease activity index (CDAI) is the most widely used measure of clinical disease activity in patients entered into clinical trials. The prospective nature of the CDAI calculation precludes its use as a clinical assessment tool. We compared the retrospective evaluation of the CDAI with the prospective evaluation in a heterogeneous patient population of 100 patients with Crohn's disease. The correlation between the two assessment methods was good with an r-value of 0.84 (p < 0,0001). There was a tendency of patients with a high retrospective CDAI to have a lower prospective CDAI which is explained by intention to treat. This study shows that a retrospective assisted evaluation of the CDAI is as accurate as the traditional prospective evaluation.