Pediatric Crohn Disease Activity Index: Responsive to Short-term Change

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Abstract
Despite documented feasibility, reliability, and validity, the Pediatric Crohn's Disease Activity Index (PCDAI) has yet to be demonstrated to be sensitive to change in the time frame of acute treatment trials. We evaluated short-term responsiveness and determined the minimal change in PCDAI score associated with a clinically meaningful improvement in disease activity. Standardized effect size (SES) and standardized response mean (SRM) were calculated as measures of responsiveness among pediatric patients being treated for acute exacerbations of Crohn disease 1) in a regular clinical practice setting and 2) as part of a multicenter, randomized controlled trial (RCT). Receiver operating characteristic (ROC) curves were constructed to determine the minimal PCDAI score change associated with significant clinical improvement used as the gold standard in 1) physician global assessment of change and in 2) change in adult Crohn disease activity index (CDAI). Among responders, the SES and SRM of the PCDAI were 1.78 and 1.41 (95% CI: 0.89–1.92) and 2.10 and 1.95 (95% CI: 1.70–2.20) in the clinical practice setting and RCT setting, respectively. The optimal minimal PCDAI change score associated with clinically significant change in physician global assessment was determined to be -12.5 (sensitivity 83.3%, specificity 92.3%). In the RCT setting a change in PCDAI of –10 corresponded to a change in CDAI of ≱ 70 points. The PCDAI is responsive to improvement in disease activity in Crohn disease patients over a short interval. As such, the PCDAI is an appropriate instrument to use in pediatric acute treatment trials.