A Retrospective Study on Functional Outcome Measures in Patients with Stiff-Person Syndrome
Mallory Lowe1, Kelli Money2, Tyler Borko1, Paul Crane3, Kunbin Qu4, Stefan Sillau1, Eric Engebretson1, Sham Dholakia4, James Chung4, Esther Nie4, Kavita Nair1, Aaron Carlson1, Amanda Piquet1
1University of Colorado, 2UCHealth Neurology Clinic- Memorial Hospital North, 3University of Utah, 4Kyverna
Objective:
The objective of this study is to retrospectively analyze change in the timed 25-feet walk (T25FW) and modified Rankin Scale (mRS) for established SPSD patients.
Background:
Stiff Person Syndrome Spectrum Disorder (SPSD) is a rare autoimmune disorder characterized by progressive muscle stiffness and painful spasms.
Design/Methods:
We queried Health Data Compass (HDC), from 2012 through 2022 for all patients ≥ 18-year-old with ICD-10 codes pertaining to SPSD in a recent epidemiology to define incidence and prevalence of SPSD (in press). 273 records were reviewed for diagnostic confirmation using the proposed Mayo Clinic and Johns Hopkins clinical criteria. Only antibody-positive patients were included in this retrospective outcome study. All statistical analyses were conducted in R statistical computing software. We grouped all the patients and the measurements together within each year. Linear regression and Mixed Model for Repeated Measures (MMRM) were used to analyze the T25FW change from baseline. MMRM models patient-specific random effects to account for intra-patient variability.
Results:
32 patients met inclusion criteria. 18 patients had T25FW data with 69 measurements, and 27 patients had retrospective mRS with 368 measurements. Average baseline T25FW was 9.4 ± 4.0 seconds. The change from baseline in the T25FW in the first year was -1.7 seconds, followed by a gradual increase with a positive change of 2.5 seconds at year 6, modeled by linear regression and MMRM. Average baseline mRS was 2.7 ± 1.3, with no apparent change over an average observation period of 3.3 ± 2.7 year (median = 0).
Conclusions:
This retrospective analysis using the T25FW shows that SPSD is a chronic and progressive disease, even under active treatment. T25FW has value in understanding disease severity and progression and may be useful to monitor therapy response. mRS is insensitive to disease progression in mild-moderate disability SPSD patients.
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