Objective: To determine the sensitivity to change within 12 months as well as completion time of the Progressive Supranuclear Palsy Functional Disability Scale (PSPFDS).

Background: Progressive Supranuclear Palsy (PSP) is a debilitating disease, affecting a broad spectrum of functional domains to variable degrees. The PSP Rating Scale (PSPRS) is an established disease-specific 28-item tool to rate the broad range of symptoms, providing reproducible progression rates of PSP-Richardson’s syndrome (PSP-RS) within 12 months in multi-centric trials. However, it is used mainly by experts in research contexts. Therefore, we aimed to develop a short and simple scale for use in clinical care and research to monitor the presence and progression of the deficits in the seven functional domains (akinesia-rigidity, bradyphrenia, communication, dysphagia, eye movements, finger dexterity, gait & balance) relevant to all clinical phenotypes of PSP. All domains are rated with a score ranging from 0 to 3 (no, mild, moderate, or severe deficits).

Method: Patients fulfilling the MDS-PSP diagnostic criteria were recruited in the prospective DescribePSP multi-center observational study. The information required for PSPFDS rating was collected through a semi-structured interview with the patient and a reliable caregiver and a short structured clinical examination at baseline and 12-months follow-up examination.

Results: N=23 patients had baseline and 12-months follow-up ratings (N=16 PSP-RS, N= 7 variant phenotypes; N=17 males; age at baseline 68.9±6.5 years). Mean completion time of the PSPFDS by experienced raters was 4.37 minutes, vs. 16.03 minutes for the PSPRS. PSFDS showed significant 1-year change (baseline 6.9±2.1; follow-up 9.7±3.0; annualized difference 3.5±3.3;P<0.001). The standardized effect size for the PSPFDS (1.05) was similar to that of the PSPRS (1.27). The sample sizes required per arm for a 2-arm, 1-year follow-up therapeutic trial to detect 50% change was estimated to be 59 (2-sided, 2-sample t test).

Conclusion: Although based on a small cohort, these findings provide evidence that the PSPFDS is sensitive to detect disease progression in PSP within a 12-months period. Prospective collection of data with a larger sample size and longer duration in PSP-RS and variant PSP-phenotypes is ongoing.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-progressive-supranuclear-palsy-functional-disability-scale-sensitivity-to-change/