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Lookup NU author(s): Professor John-Paul TaylorORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© The Author(s), 2025. Published by Cambridge University Press. Background: Hallucinations are common and distressing symptoms in Parkinson's disease (PD). Treatment response in clinical trials is measured using validated questionnaires, including the Scale for Assessment of Positive Symptoms-Hallucinations (SAPS-H) and University of Miami PD Hallucinations Questionnaire (UM-PDHQ). The minimum clinically important difference (MCID) has not been determined for either scale. This study aimed to estimate a range of MCIDs for SAPS-H and UM-PDHQ using both consensus-based and statistical approaches. Methods A Delphi survey was used to seek opinions of researchers, clinicians, and people with lived experience. We defined consensus as agreement ≥75%. Statistical approaches used blinded data from the first 100 PD participants in the Trial for Ondansetron as Parkinson's Hallucinations Treatment (TOP HAT, NCT04167813). The distribution-based approach defined the MCID as 0.5 of the standard deviation of change in scores from baseline at 12 weeks. The anchor-based approach defined the MCID as the average change in scores corresponding to a 1-point improvement in clinical global impression-severity scale (CGI-S). Results: Fifty-one researchers and clinicians contributed to three rounds of the Delphi survey and reached consensus that the MCID was 2 points on both scales. Sixteen experts with lived experience reached the same consensus. Distribution-defined MCIDs were 2.6 points for SAPS-H and 1.3 points for UM-PDHQ, whereas anchor-based MCIDs were 2.1 and 1.3 points, respectively. Conclusions: We used triangulation from multiple methodologies to derive the range of MCID estimates for the two rating scales, which was between 2 and 2.7 points for SAPS-H and 1.3 and 2 points for UM-PDHQ.
Author(s): Reeves S, Mahdi J, Appleby M, Zubko O, Lee T, Barber JA, Liu KY, Taylor J-P, Henderson EJ, Schrag A, Howard R, Weil RS
Publication type: Article
Publication status: Published
Journal: Psychological Medicine
Year: 2025
Volume: 55
Online publication date: 24/03/2025
Acceptance date: 18/02/2025
Date deposited: 14/04/2025
ISSN (print): 0033-2917
ISSN (electronic): 1469-8978
Publisher: Cambridge University Press
URL: https://doi.org/10.1017/S0033291725000534
DOI: 10.1017/S0033291725000534
Data Access Statement: Data are not available for sharing as recruitment to the TOP HAT trial is ongoing.
PubMed id: 40125723
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