Annual Meeting of the North American Society for Pediatric Gastroenterology and Nutrition; Orlando, October 22-24, 1998
LONGITUDINAL VALIDATION OF THE PCDAI
The Pediatric Crohn's Disease Activity Index (PCDAI) is a simple quantitative instrument designed to aid in the classification of children with Crohn's disease (CD) (J Pediatr Gastro Nutr 1991;12:439). It has high correlation with a physician's global assessment and the Harvey-Bradshaw (HB) score. It has been proposed as a tool for multicenter protocols due to its low interobserver variability. However, PCDAI validity has not been studied longitudinally, and so it has not yet been accepted as an index on which to base future therapeutic trials. We report longitudinal PCDAI measurements obtained during the course of a prospective, multicenter 18 month clinical trial. Methods: 55 children (ages 13±2 yrs) with moderate-severe CD activity were enrolled in a placebo-controlled trial of the effects of 6MP + prednisone in children with newly diagnosed CD. Both PCDAI and HB scores were calculated at entry into the study, and at months 1, 2, 6, 12, and 18. Correlation between PCDAI and HB was determined by Spearman coefficients. Disease severity was defined by HB score (inactive 0-2, mild 3-4, moderate-severe ≥5). Corresponding PCDAI scores for these disease severity categories were determined, and compared by Wilcoxin scores and Kruskal-Wallis test. Differences were considered significant for p<0.05. Results: 187 paired observations were made in the 55 subjects. Correlation between HB and PCDAI scores was identical in both treatment groups and so the groups were combined for analysis. The PCDAI and HB scores during the first 6 months of study (141 paired observations) revealed a correlation coefficient of R=0.90. Additional observations to 18 months of study (total 187 pairs) resulted in R=0.89. Based on HB definitions, 112 observations revealed inactive disease, 14 mild, and 61 moderate-severe disease activity. The corresponding PCDAI scores for each group (mean/std.dev/median) were: inactive 5.7/6.1/5.0; mild 16.8/6.1/16.3; moderate-severe 41.1/12.9/42.5. Differences between PCDAI categories were highly significant (p=0.0001). Conclusions: PCDAI is a useful quantitative tool for assessing changes of CD activity over time. Longitudinal PCDAI scores can be used as a numerical measure of response in future pediatric therapeutic trials.
Abdominal Pain/IBD/Outcomes© 1998 Lippincott Williams & Wilkins, Inc.