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Updated: Jul 19, 2025
The Multiple Sclerosis Performance Test MSPT: An iPad-Based Disability Assessment Tool
Published on: June 30, 2014
The Patient-Determined Disease Steps scale is not interchangeable with the Expanded Disease Status Scale in mild to
Yi Chao Foong1,2,3,4, Daniel Merlo1,3, Melissa Gresle1,2,5
1Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia.
Background And Purpose:
The validity, reliability, and longitudinal performance of the Patient-Determined Disease Steps (PDDS) scale is unknown in people with multiple sclerosis (MS) with mild to moderate disability. We aimed to examine the psychometric properties and longitudinal performance of the PDDS.
Methods:
We included relapsing-remitting MS patients with an Expanded Disability Status Scale (EDSS) score of less than 4. Validity and test-retest reliability was examined. Longitudinal data were analysed with mixed-effect modelling and Cohen's kappa for concordance in confirmed disability progression (CDP).
Results:
We recruited a total of 1093 participants, of whom 904 had complete baseline data. The baseline correlation between PDDS and EDSS was weak (ρ = 0.45, p < 0.001). PDDS had stronger correlations with patient-reported outcomes (PROs). Conversely, EDSS had stronger correlations with age, disease duration, Kurtzke's functional systems and processing speed test. PDDS test-retest reliability was good to excellent (concordance correlation coefficient = 0.73-0.89). Longitudinally, PDDS was associated with EDSS, age and depression. A higher EDSS score was associated with greater PDSS progression. The magnitude of these associations was small. There was no concordance in CDP as assessed by PDDS and EDSS.
Conclusion:
The PDDS has greater correlation with other PROs but less correlation with other MS-related outcome measures compared to the EDSS. There was little correlation between PDDS and EDSS longitudinally. Our findings suggest that the PDDS scale is not interchangeable with the EDSS.
Insights
The Patient-Determined Disease Steps (PDDS) scale shows good reliability in multiple sclerosis (MS) patients but does not correlate well with the Expanded Disability Status Scale (EDSS) over time. PDDS is not interchangeable with EDSS for assessing MS progression.
Area of Science:
- Neurology
- Clinical Research
- Patient-Reported Outcomes
Background:
- The validity and reliability of the Patient-Determined Disease Steps (PDDS) scale are unknown in multiple sclerosis (MS) patients with mild to moderate disability.
- Assessing disease progression in MS is crucial for treatment decisions and requires reliable outcome measures.
Purpose of the Study:
- To examine the psychometric properties, including validity and test-retest reliability, of the PDDS scale in MS patients.
- To evaluate the longitudinal performance of the PDDS scale and its correlation with the Expanded Disability Status Scale (EDSS).
Main Methods:
- Included relapsing-remitting MS patients with an EDSS score < 4.
- Assessed validity and test-retest reliability of PDDS.
- Analyzed longitudinal data using mixed-effect modeling and Cohen's kappa for confirmed disability progression (CDP).
Main Results:
- PDDS showed a weak baseline correlation with EDSS (ρ=0.45) but stronger correlations with patient-reported outcomes (PROs).
- PDDS demonstrated good to excellent test-retest reliability (CCC=0.73-0.89).
- Longitudinally, PDDS correlated weakly with EDSS, age, and depression, with no concordance in CDP between PDDS and EDSS.
Conclusions:
- PDDS correlates better with PROs than EDSS but shows limited correlation with other MS outcome measures.
- PDDS and EDSS are not interchangeable for assessing MS disability and progression.
- The PDDS scale may offer a valuable patient-centered perspective but should not replace established clinical measures like EDSS.
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