Category: Huntington's Disease
Objective: To assess the impact of task repetition on performance in digital assessments on Huntington’s disease (HD) and establish the number of practice test iterations required to accurately estimate true performance changes.
Background: Digital monitoring tools enable remote assessment of HD signs and symptoms in patients’ daily lives at a higher frequency than clinician-administered tests. Studies have shown that most gold-standard tests are influenced by practice effects; i.e. the improvement in performance over time resulting from the repetition of a task. During initial digital testing sessions, changes in performance may be confounded by test-taking strategies, initial difference in manual dexterity or test/device knowledge. It is key to distinguish between a participant’s short familiarisation period with the test, and subsequent longitudinal changes related to disease progression and continued practice. Practice-induced changes might be larger than true functional alterations during the learning phase, confounding the interpretation of clinical results which use a change from baseline approach.
Method: Seven motor and cognitive smartphone-based assessments were completed daily or weekly by individuals with manifest HD (n=36), premanifest HD (n=20) and healthy controls (n=20) in the Digital-HD study. A two-phase learning curve model characterised individual practice and longitudinal effects. Based on the model’s estimation of familiarisation period duration and performance changes, the impact on each task and disease group performance was established.
Results: While subjects experienced practice effects for cognitive tasks (e.g. the Symbol Digit Modalities Test), some motor tasks (e.g. the 2-Minute Walk Test) were free of such effects. When practice did take place, less than 10 test iterations were required for the subject to reach a stable test performance.
Conclusion: Practice effects can be characterised using high-frequency remote patient monitoring, and mitigation strategies implemented as part of the study design to facilitate accurate interpretation of clinical trial results.
To cite this abstract in AMA style:A. Wolfer, F. Lipsmeier, R. Tortelli, F.B Rodrigues, L.M Byrne, C. Simillion, T. Kilchenmann, A. Bamdadian, S.A Schobel, E.J Wild, M. Lindemann. Remote and frequent assessment of Huntington’s disease in clinical trials: Strategies for assessing and accounting for the practice effect [abstract]. Mov Disord. 2020; 35 (suppl 1). https://www.mdsabstracts.org/abstract/remote-and-frequent-assessment-of-huntingtons-disease-in-clinical-trials-strategies-for-assessing-and-accounting-for-the-practice-effect/. Accessed December 10, 2023.
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