T-32: Development of a Cognitive Assessment Score Transformation (CAST) System to Support the TOMMORROW Study
Alexandra S. Atkins
Senior Scientific Director
NeuroCog Trials United States
Describe collaborative development of the Cognitive Assessment Score Transformation (CAST) system designed to reduce site burden and improve interpretation of cognitive tests administered in the TOMMORROW study to delay onset of mild cognitive impairment (MCI) due to Alzheimer’s disease (AD).
Published normative tables for individual neurocognitive tests were integrated into a single CAST system to allow automated calculation of and seamless access to standardized test scores (z scores) needed to determine subject eligibility and subsequently to evaluate potential conversion to MCI-AD.
Development and implementation of the CAST system represents a broad collaboration of sponsor and vendor representatives with expertise in neurocognitive evaluation, the use of normative data, statistics, data management, and clinical trial operations. The CAST system supports accurate and efficient transformation of raw neurocognitive test scores to standardized scores based on normative data that is demographically appropriate for each subject enrolled in the Phase 3 TOMMORROW trial. To date, the CAST system has been successfully implemented for more than 15,000 administrations of the neurocognitive battery collected within the trial. Each assessment includes the following measures: California Verbal Learning Test – 2nd Edition (CVLT-II); Brief Visuospatial Memory Test – Revised (BVMT-R); WAIS-III Digit Span; Trail Making Test – Parts A and B; Multilingual Naming Test (MINT); Semantic Fluency; Lexical Fluency; Clock Drawing Test (CDT). After data quality review and circumscribed central scoring (BVMT measures), raw test scores for each cognitive measure are entered into the electronic data capture (EDC) database by the cognitive vendor within 2 days of test administration. The CAST system provides standardized z scores based on normative data matched to the demographic characteristics of each subject. These z scores are automatically evaluated against predefined cut-off criteria for subject eligibility (baseline visit) or operationalized ‘trigger’ criteria for decline in cognitive performance (follow-up). Standardized scores are transferred back to the EDC database for clinical interpretation by site principal investigators and neuropsychologists. Compared with traditional methods used to calculate normative scores for tests (manual table look-up, individualized scoring programs), the CAST system provides substantial improvements in the transparency, efficiency, and accuracy of normative score transformations, while significantly reducing site burden.
The need for timely clinical interpretation of standardized test scores for cognitive test batteries that have been assembled from multiple instruments can represent a challenge for time-to-event trials in MCI-AD. Investment of time and expertise in the development of utilities such as the CAST system can substantially reduce the burden of reliance on standardized scores by providing streamlined access to both raw and standard scores that are critical to clinical decision making and diagnosis. Such utilities can improve overall data quality while dramatically reducing burden on investigational sites participating in large-scale clinical trials.