Using Downgaze Palsy Progression Rate to Model Survival in Progressive Supranuclear Palsy–Richardson Syndrome

ABSTRACT Background Rapid development of downgaze palsy, the most specific symptom of progressive supranuclear palsy (PSP), has been associated with shorter survival in small studies. Objective We hypothesized that the progression rate of downgaze palsy and other disease features could predict survival if assessed soon after the onset of downgaze palsy in a large data set. Methods We used a longitudinal database of 414 patients with probable PSP‐Richardson syndrome from 1994 to 2020. The data set comprised demographics and, for each visit, 28 PSP Rating Scale (PSPRS) items and PSP stage scores. We calculated the rate of progression of each PSPRS item as its item score when the downgaze item first reached 1 or more (on a 0–4 scale) divided by disease duration at that point. Multivariate Cox regression was applied to identify variables independently associated with survival. We also explored the progression pattern of total PSPRS and downgaze palsy scores with disease course. Results Independently associated with shorter survival were older onset age and faster progression of downgaze palsy, dysphagia for liquids, difficulty in returning to seat, and PSP stage. Patients with survival duration within 1 year of the median survival (6.58 years) showed approximately linear progression of the PSPRS score and downgaze palsy score during years 2 through 6 of the disease course. Conclusions Older onset age and faster progression of downgaze palsy and several axial features are associated with shorter survival. The disease typically progresses in approximately linear fashion during years 2 through 6. These results may aid study design and patient counseling. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society. In progressive supranuclear palsy (PSP)–Richardson syndrome (N = 414), we found that older onset age and faster progression of downgaze palsy and several axial features in the PSP Rating Scale (PSPRS) are associated with shorter survival. PSPRS and downgaze palsy scores progress in approximately linear fashion through year 6. These results aid study design and patient counseling.