Unintended consequences of evolution of the Common Terminology Criteria for Adverse Events

Background Adverse events (AEs) on Children's Oncology Group (COG) trials are reported manually by clinical research assistants (CRAs). The Common Terminology Criteria for Adverse Events (CTCAE) was developed to provide standardized definitions for identifying and grading AEs. The CTCAE has expanded significantly over its five versions, but the impact of CTCAE definitional changes has not been examined. Procedure This study compared AE number and ascertainment among the first four CTCAE versions using a case vignette. Each CTCAE version was used to create a list of AEs and grades by two separate CRAs. Results The CTCAE expanded from 9 categories and 49 AEs in v1.0 to 26 categories and 790 AEs in v4.0. CRAs independently selected different approaches to AE ascertainment-comprehensive and parsimonious. The number of AEs identified in the parsimonious approach was stable with 10-14 in each CTC version. The comprehensive approach identified 9, 20, 29, and 37 AEs in CTC versions 1.0, 2.0, 3.0, and 4.0, respectively. Only approximately 65% of AEs were conclusively graded in versions 2.0 to 4.0 using the comprehensive approach. Conclusions CTCAE has increased in complexity. Although this increased complexity allows for more granular AE reporting, these data demonstrate potential unintended negative consequences of increasing CTC AE complexity, including the risk of varying approaches to AE capture. A comprehensive evaluation of CTC AE definitions and CRA reporting practices across COG institutions and AEs are needed to improve the accuracy and efficiency of AE reporting.