Embedding Patient Input in Outcome Measures for Long-Term Disease-Modifying Parkinson Disease Trials

Background: Clinical trials of disease-modifying therapies in PD require valid and responsive primary outcome measures that are relevant to patients. Objectives: The objective is to select a patient-centered primary outcome measure for disease-modification trials over three or more years. Methods: Experts in Parkinson's disease (PD), statistics, and health economics and patient and public involvement and engagement (PPIE) representatives reviewed and discussed potential outcome measures. A larger PPIE group provided input on their key considerations for such an endpoint. Feasibility, clinimetric properties, and relevance to patients were assessed and synthesized. Results: Although initial considerations favored the Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part III in Off, feasibility, PPIE input, and clinimetric properties supported the MDS-UPDRS Part II. However, PPIE input also highlighted the importance of nonmotor symptoms, especially in the longer term, leading to the selection of the MDS-UPDRS Parts I + II sum score. Conclusions: The MDS-UPDRS Parts I + II sum score was chosen as the primary outcome for large 3-year disease-modification trials.