Tracking Emergence of New Motor and Non-Motor Symptoms Using the MDS-UPDRS: A Novel Outcome Measure for Early Parkinson's Disease?

Background: Summary scores of current clinical rating scales do not appear sensitive enough to quantify changes in disease progression in early Parkinson's disease (PD) clinical trials. An alternate approach might be to track the appearance of new or emergent symptoms (ES) over time as a measure of disease progression. Objective: Explore the potential utility of patient reported ES as an outcome measure during the early phase of PD. Methods: We analyzed data from the MDS-UPDRS Parts IB (non-motor) and II (motor) Experiences of Daily Living scales over two years in the STEADY-PD3 study. We assessed the number of ES reported in each part of the scale in both participants who started symptomatic treatment and those who did not (STx-yes/no) in two periods: between 0 and 12-months (Year 1), and 13 and 24-months (Year 2). Results: Of 331 participants, 87% developed ES, and 55% started STx in Year 1. The median number of Part IB ES did not significantly differ between STx groups, but ES in Part II were significantly more frequent in the STx-yes group. Of 148 participants who remained STx-no into Year 2, 77% developed ES, and 42% started STx. Again, Part II, but not Part IB ES were more frequent the STx-yes group. Using these results, a sample size of similar to 90 per group would be required to detect a 30% reduction in combined Part IB and II ES over 12 months. Conclusion: Assessing ES of patient-reported experiences of daily living may provide a useful marker for tracking PD progression.