Category: Parkinson's Disease (Other)
Objective: To evaluate the inter-rater reliability (IRR) of the MDS-PDPRS in a pilot clinimetric cohort.
Background: No validated outcome assessment exists to measure the functional impact of Parkinson’s Disease Psychosis (PDP) (1). The MDS-PDPRS is a clinician-reported outcome evaluating PDP severity and daily activity effects, comprising a 13-item, two-part inventory: Part 1. PDP Screening Questionnaire – Diagnosis (3 items), Complexity, and Frequency (2 items), which determine whether the individual meets the criteria for PDP; and Part 2. Functional Impact (8 items)(2). Strong IRR is a key clinimetric requirement.
Method: Dyads of participants with PDP (PwPDP) and care partners were independently assessed by two trained raters, a clinician and a nurse with more than 3 years of experience in PD. IRR was quantified using intraclass correlation (ICC), two-way random effects, for summary scores, and linear-weighted Cohen’s kappa (κ) for individual ordinal items and unweighted κ for binary items.
Results: The cohort included 19 PwPDP (57.9% male; age range 64–81, mean age=72.0 years, SD±4.9; MoCA range 10–29, median=24; H&Y stage range 1–4, median=2) and 16 care partners (68.4% female; age range 61–80, mean=69.8, SD±5.2; MoCA range 23–30, median=27.5). Agreement was excellent for the Total Score (ICC=0.922), Part I (ICC=0.943), Part II (ICC=0.917), and Part I–Frequency (ICC=0.982); Part I–Complexity was moderate (ICC=0.659). Near-perfect agreement was observed for sense of passage, sense of presence, hallucinations, and PDP criteria (all κ=1.000), and for sleep (κ=0.937) and illusions (κ=0.894). Substantial agreement was observed in the following items: household activities (κ=0.737), self-care (κ=0.733), cognition (κ=0.704), recreational activities (κ=0.673), and personal close relations (κ=0.623). Going outside the house showed moderate agreement (κ=0.526). Items related to delusions were not analyzed as they were present in only 5 patients. In the additional research question (not part of the MDS-PDPRS), raters also showed substantial agreement that patients are the most reliable source of information (κ=0.723).
Conclusion: These preliminary findings demonstrate excellent-to-good IRR across scores and most items, providing a basis for completing further MDS-PDPRS validation.
References: Acknowledgments: The MDS-PDPRS program is supported by a grant from Acadia Pharmaceuticals to the International Parkinson and Movement Disorders Society.
References:
1. Mangone G, Tosin MHS, Goetz CG, Stebbins GT, Mestre TA. Unveiling Assessment Gaps in Parkinson’s Disease Psychosis: A Scoping Review. Mov Disord. 2024. Epub ahead of print. PMID: 38291860.
2. Tosin MHS, Mestre TA, Stebbins GT, Mangone G, Videmsky S, Ali S, Aarsland D, Goldman J, Khoo T, Lewis S, Martinez-Martin P, Ojo O, Pagonabarraga J, Schrag A, Weintraub D, Goetz CG. Conceptualization of the MDS Parkinson’s Disease Psychosis Rating Scale (MDS-PDPRS) prototype. [abstract]. Mov Disord. 2024; 39 (suppl 1).
To cite this abstract in AMA style:
M. Tosin, T. Mestre, G. Stebbins, L. Montoya-Quinchia, S. Videmsky, S. Ali, D. Aarsland, J. Goldman, T. Khoo, S. Lewis, P. Martinez-Martin, O. Ojo, J. Pagonabarraga, A. Schrag, D. Weintraub, C. Goetz. Toward a Standardized Measure of Parkinson’s Disease Psychosis: Preliminary Inter-Rater Reliability of the MDS Parkinson’s Disease Psychosis Rating Scale (MDS-PDPRS) [abstract]. Mov Disord. 2026; 41 (suppl 1). https://www.mdsabstracts.org/abstract/toward-a-standardized-measure-of-parkinsons-disease-psychosis-preliminary-inter-rater-reliability-of-the-mds-parkinsons-disease-psychosis-rating-scale-mds-pdprs/. Accessed October 1, 2026.« Back to 2026 International Congress
MDS Abstracts - https://www.mdsabstracts.org/abstract/toward-a-standardized-measure-of-parkinsons-disease-psychosis-preliminary-inter-rater-reliability-of-the-mds-parkinsons-disease-psychosis-rating-scale-mds-pdprs/