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Updated: Jul 16, 2026
The Multiple Sclerosis Performance Test MSPT: An iPad-Based Disability Assessment Tool
Published on: June 30, 2014
Middle-range scores from the patient determined disease steps scale reflect varying levels of walking dysfunction in
Robert Motl1, Whitney Neal2, Deborah Backus3
1Department of Kinesiology and Nutrition, University of Illinois at Chicago, 1919 West Taylor St, Applied Health Sciences Building, Room 506J, Chicago, IL, 60612, USA. robmotl@uic.edu.
Background:
Multiple sclerosis (MS) is a leading cause of neurological disability among young and middle-aged adults worldwide, and disability is measured using a variety of approaches, including patient reported outcome measures (PROMs) such as the Patient Determined Disease Steps (PDDS) scale. There is limited evidence for the validity of inferences from the middle-range of scores on the PDDS (i.e., 3 "gait disability" - 6 "bilateral support"), but that range of scores seemingly represents moderate disability characterized by varying levels of walking dysfunction.
Purpose:
The current study examined whether the middle-range of scores from the PDDS reflect varying levels of walking dysfunction among people with MS.
Method:
Participants (N = 374) completed the Patient Determined Disease Steps (PDDS) scale, Multiple Sclerosis Walking Scale-12 (MSWS-12), timed 25-foot walk (T25FW), six-minute walk (6 MW), Modified Fatigue Impact Scale (MFIS), and Multiple Sclerosis Impact Scale-29 (MSIS-29), and underwent a neurological exam for generating an Expanded Disability Status Scale (EDSS) score as part of screening and baseline data collection for a clinical trial of exercise training in MS. We undertook a series of linear trend analyses that examined differences in the outcomes of EDSS, T25FW, 6 MW, MSWS-12, MFIS subscales, and MSIS-29 subscales across the 4 levels of PDDS scores (i.e., 3-6).
Results:
There were statistically significant and strong linear trends for EDSS (F1,370 = 306.1, p < .0001, η2 = 0.48), T25FW (F1,370 = 161.0, p < .0001, η2 = 0.32), 6 MW (F1,370 = 178.9, p < .0001, η2 = 0.34), and MSWS-12 (F1,370 = 97.0, p < .0001, η2 = 0.24). There was a strong correlation between PDDS and EDSS scores (rs = 0.695, 95% CI = 0.643, 0.748). Both PDDS and EDSS scores had strong correlations with walking outcomes, yet weaker correlations with measures of fatigue and QOL.
Conclusion:
The PDDS could serve as a simple, inexpensive, and rapidly administered PROM for remote screening and early detection of walking dysfunction for initial eligibility into clinical trials and practice for managing mobility-specific disability in MS.
Registration:
The study was registered on ClinicalTrials.gov on March 19, 2018 (NCT03468868).
