Objective: To examine the association between time to Parkinson Disease (PD) health administrative data milestones and a one-year change in the Movement Disorders Society – Unified Parkinson Disease Rating Scale Motor Subscore (MDS-UPDRS III).
Background: The change in MDS-UPDRS III is a commonly used measure of PD progression in clinical trials of disease-modifying therapies and a key assumption is that smaller changes in MDS-UPDRS III over time indicate slower PD progression. However, it is unclear if this measure correlates with long-term progression. Time to health administrative data milestones such as time to dementia, long-term care or death have been used in observational studies but have not been tested for their correlation with the MDS-UPDRS III.
Method: We designed a retrospective cohort study using clinical data from the Toronto Western Hospital Movement Disorders Clinic linked to milestones measured in health administrative data. The cohort included 197 consecutive individuals living with PD aged ≥ 40 years old who had MDS-UPDRS III measures collected one year apart. PD milestones included time to home care services, falls, dementia, nursing homes and death. The index date was the first MDS-UPDRS III measure date. The observation window ended upon death, end of healthcare coverage or June 30, 2024. Unadjusted and adjusted Fine-Gray models evaluated the association between changes in MDS-UPDRS III scores and the hazard ratios (HR) of PD milestones, accounting competing risks of death.
Results: Individuals were aged 66.2 (9.9) years (mean (SD)) and included 64.5% males. Individuals had symptoms for an average of 3.27 years before index date and were followed for 11.2 years. The mean MDS-UPDRS III score was 25.3 (12.0) at baseline and 24.5 (12.6) at one year. The change in MDS-UPDRS III scores at 1 year was not associated with the incidence of PD milestones including time to home care services (adjusted HR=1.02, 95% CI: 1.00, 1,03), time to falls (HR=1.00, 0.98, 1.02), time to dementia (HR=1.00, 0.98, 1.02), time to nursing home (HR=1.02, 0.99, 1.05) and death (HR=0.99, 0.97, 1.00).
Conclusion: A change in MDS-UPDRS III measured early in PD did not correlate with the incidence of PD milestones captured in health administrative data. Trials in PD may consider additional measures of PD progression.
To cite this abstract in AMA style:
P. Gros, S. Bronskill, S. Dorrance, X. Wang, M. Chiu, M. Farkouh, C. Marras. The Movement Disorders Society Unified Parkinson Disease Rating Scale Motor Subscore Is Not Associated With Future Parkinson Disease Milestones – an observational study using linked health administrative data [abstract]. Mov Disord. 2025; 40 (suppl 1). https://www.mdsabstracts.org/abstract/the-movement-disorders-society-unified-parkinson-disease-rating-scale-motor-subscore-is-not-associated-with-future-parkinson-disease-milestones-an-observational-study-using-linked-health-adm/. Accessed October 5, 2025.« Back to 2025 International Congress
MDS Abstracts - https://www.mdsabstracts.org/abstract/the-movement-disorders-society-unified-parkinson-disease-rating-scale-motor-subscore-is-not-associated-with-future-parkinson-disease-milestones-an-observational-study-using-linked-health-adm/