OBJECTIVES: Prior Parkinson’s disease (PD) studies are limited by short follow-up and have not reported on events associated with PD progression. The purpose of this study was to characterize PD progression-related events over time among PD cases and compare to PD controls.

METHODS: This retrospective cohort study utilized administrative medical and pharmacy claims data from 2005 to 2015 for Medicare beneficiaries represented in the Medicare Chronic Condition Data Warehouse (CCW) 5% sample. We matched cases to controls based on age, race, gender and comorbidities. Cases and controls were required to have at least 7 years of follow-up. We captured the presence of mental health disorders, autonomic dysfunction, falls or fractures (FoF), and fatigue in each year of follow-up. We compared these progression-related events between cases and controls using Pearson’s chi-square tests.

RESULTS: The matched sample consisted of 3,570 individuals with 7 years of follow-up. The occurrence of events among cases in years 1, 3, 5 and 7 was as follows. Autonomic dysfunction: 69%, 68%, 73%, 75%; mental health disorders: 53%, 52%, 59%, 66%; FoF: 21%, 18% 20%, 22%; fatigue: 41%, 35%, 36%, 38%, respectively. The occurrence of all four events was higher among cases compared to controls in each year. The largest difference between cases and controls was observed in year 1: autonomic dysfunction (69% vs. 45%, p<0.01); mental health disorders (53% vs. 18%, p<0.01); FoF (21% vs. 9%, p<0.01); fatigue (41% vs. 23%, p<0.01). The differences between cases and controls dropped in year 3, but increased in years 5 and 7.

CONCLUSIONS: Progression-related events occurred at significantly higher rates among PD cases compared to controls in each year of follow-up. The differences between cases and controls were highest in year 1. Among cases, the largest increase in autonomic dysfunction and mental health disorders occurred between years 3 and 5.