Crohn's disease activity index does not correlate with endoscopic recurrence one year after ileocolonic resection

Crohn's disease clinical trials utilize the Crohn's Disease Activity Index (CDAI) to measure primary endpoint assessments of clinical recurrence and remission. We evaluated the extent of agreement between clinical recurrence/remission as defined by the CDAI and endoscopic recurrence 1 year after intestinal resection for Crohn's disease (CD).

Twenty-four CD patients who had been randomly assigned to a postoperative clinical trial had 1 year clinical, endoscopic, and histological assessment for disease recurrence. The primary endpoint was the extent of agreement between endoscopic recurrence and clinical recurrence 1 year after intestinal resection for CD. Secondary endpoints were extent of agreement between endoscopic recurrence and the surrogate markers of CD activity, i.e., histological activity, sedimentation rate, and C-reactive protein (CRP).

Twelve of the 24 patients (50%) were in endoscopic remission (i0, i1) and 12 (50%) had endoscopic recurrence (i2, i3, or i4). There was good agreement between endoscopy and histological activity scores (intraclass correlation coefficient = 0.53, kappa coefficient = 0.58). In contrast, there was little to no relationship between endoscopy and CDAI scores; median CDAI scores for endoscopy scores of i0/i1, i2, i3, and i4 were 118, 76, 156, and 78, respectively (P for trend = 0.88). The kappa coefficient (of agreement) between endoscopy score ± 2 and CDAI score ± 150 was 0.12 (exact P = 0.68), indicating poor agreement. Similarly, there was no consistent association observed between endoscopy scores and mean CRP and ESR values at week 54.

The CDAI shows poor agreement with endoscopic recurrence 1 year after intestinal resection. Endoscopic recurrence should be the primary endpoint of future postoperative studies and ileocolonoscopy the gold standard test to detect postoperative recurrence.