Assessing disease activity using the pediatric Crohn's disease activity index: Can we use subjective or objective parameters alone?

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BACKGROUNDThe pediatric Crohn’s disease activity index (PCDAI) is used as a standard tool to assess disease activity in clinical trials for pediatric Crohn’s disease. AIMTo examine which items on the PCDAI drive assessment of disease activity, and how subgroups of subjective and objective items reflect change in disease state over time.METHODSSelective raw data from three prospectively collected datasets were combined, including 703 children with full PCDAI data at baseline, at 3-mo (Q1, n = 670), and 1-year (Q4, n = 474). Change in individual PCDAI scores from baseline to Q1 and to Q4 were examined using the non-weighted PCDAI. RESULTSAbdominal pain, well-being, weight, and stooling had the highest change scores over time. Objective indicators including albumin, abdominal exam, and height velocity followed. Change scores for well-being and abdominal exam did not explain significant variance at Q1 but were significant predictors at Q4 (P < 0.001 and P < 0.05). Subjective and objective subgroups of items predicted less variance (18% and 22%) on total PCDAI scores at Q1 and Q4 compared to the full PCDAI, or a composite scale (both 32%) containing significant predictors. CONCLUSIONAlthough subjective items on the PCDAI change the most over time, the full PCDAI or a smaller composite of items including a combination of subjective and objective components classifies disease activity better than a subgroup of either subjective or objective items alone. Reliance on subjective or objective items as stand-alone proxies for disease activity measurement could result in misclassification of disease state.