Pediatric Crohn Disease Clinical Outcome Assessments and Biomarkers: Current State and Path Forward for Global Collaboration

Developmental Pharmacodynamics and Modeling in Pediatric Drug Development

Challenges in pediatric drug development include small patient numbers, limited outcomes research, ethical barriers, and sparse biosamples. Increasingly, pediatric drug development is focusing on extrapolation: leveraging knowledge about adult disease and drug responses to inform projections of drug and clinical trial performance in pediatric subpopulations. Pharmacokinetic-pharmacodynamic (PK-PD) modeling and extrapolation aim to reduce the numbers of patients and data points needed to establish efficacy. Planning for PK-PD and biomarker studies should begin early in the adult drug development program. Extrapolation relies on the assumption that both the underlying disease and the mechanism of action of the drug used to treat that disease are similar in adults and pediatric subpopulations. Clearly, developmental changes in PK and PD need to be considered to enhance the quality of PK-PD modeling and, therefore, increase the success of extrapolation. This article focuses on the influence of differences in PD between adults and pediatric subpopulations that are highly relevant for the use of extrapolation.

Do Children and Adolescents With Inflammatory Bowel Disease Complete Clinical Disease Indices Similar to Physicians?

OBJECTIVES

The degree to which children and adolescents with inflammatory bowel disease (IBD) complete clinical disease activity indices in accordance with their physician is indefinite. Therefore, we investigated the agreement between patient- and physician-based clinical indices in children and adolescents with a previous diagnosis of IBD.

METHODS

In this cross-sectional study, IBD patients (8-18 years) were included prospectively. Patients completed a patient-based short Pediatric Crohn's Disease Activity Index (shPCDAI) for Crohn disease or the Pediatric Ulcerative Colitis Activity Index (PUCAI) for ulcerative or indeterminate colitis. Physicians completed the original physician-based shPCDAI or PUCAI. Agreement was calculated with linear weighted kappa.

RESULTS

In total, 154 pairs of clinical indices were collected: 89 pairs of shPCDAI's (median age at assessment 15.6 years, 61% men) and 55 pairs of PUCAI's (median age at assessment 14.0 years, 44% men). The shPCDAI disease activity category only fairly agreed between patient- and physician-based indices (kappa: 0.40 [95% confidence interval 0.24-0.55], P < 0.001), with perfect agreement in 58% of pairs. In the majority of disagreement (81%), patients scored in a higher shPCDAI disease activity category. The PUCAI disease activity category substantially agreed between patient- and physician-based indices (kappa: 0.64 [95% confidence interval 0.45-0.83], P < 0.001), with perfect agreement in 78% of pairs. In the majority of disagreement (75%), patients scored in a higher PUCAI disease activity category.

CONCLUSIONS

Patient- and physician-based shPCDAI and PUCAI do not always agree, particularly the shPCDAI, and therefore, should not be interpreted equivalently in management and research on children and adolescents with IBD.