Minimally clinically important decline in the parkinsonian variant of multiple system atrophy
Florian Krismer1, Klaus Seppi1, Gregor K Wenning1
1Department of Neurology, Medical University Innsbruck, Innsbruck, Austria.
Introduction:
We provide the first characterization of the minimally clinically important difference on the Unified Multiple System Atrophy Rating Scale in patients with the parkinsonian variant of early MSA.
Methods:
Data from a randomized controlled trial of rasagiline were analyzed using clinical global impression as an anchor. Because too few patients improved with treatment, analyses were limited to defining scale cutoffs that discriminated between minimal worsening and no change.
Results:
Based on receiver operating characteristic curves, minimally clinically important differences were 1.5 points on the activities of daily living scale, 1.5 points on the motor scale, and 3.5 points on the total scale.
Conclusions:
Appreciation of the minimally clinically important difference is important when deciding if statistically significant effects should influence practice. For the Unified Multiple System Atrophy Rating Scale, further work is required to establish cutoffs for improvement, extend relevance to cerebellar-predominant disease, and characterize progression rates at different disease stages. © 2016 International Parkinson and Movement Disorder Society.
Insights
This study defines the minimally clinically important difference for the Unified Multiple System Atrophy Rating Scale in early Parkinsonian MSA. Key differences were established for daily living, motor, and total scales to guide clinical practice.
Area of Science:
- Neurology
- Clinical Neuroscience
- Movement Disorders
Background:
- Multiple System Atrophy (MSA) is a progressive neurodegenerative disorder.
- The parkinsonian variant of MSA presents with motor symptoms similar to Parkinson's disease.
- Objective measurement of clinical change is crucial for evaluating treatments in MSA.
Purpose of the Study:
- To characterize the minimally clinically important difference (MCID) for the Unified Multiple System Atrophy Rating Scale (UMSARS).
- To establish scale cutoffs that differentiate minimal worsening from no change in early parkinsonian MSA.
- To provide a basis for interpreting treatment effects in clinical trials and practice.
Main Methods:
- Analysis of data from a randomized controlled trial of rasagiline in early MSA patients.
- Utilized Clinical Global Impression as an anchor for assessing change.
- Employed receiver operating characteristic (ROC) curves to determine scale cutoffs.
Main Results:
- Identified an MCID of 1.5 points on the UMSARS Activities of Daily Living (ADL) scale.
- Established an MCID of 1.5 points on the UMSARS Motor Scale.
- Determined an MCID of 3.5 points on the UMSARS Total Scale.
Conclusions:
- The identified MCID values are essential for interpreting statistically significant changes in clinical practice.
- Further research is needed to establish MCID cutoffs for improvement in MSA.
- Future studies should extend these findings to cerebellar-predominant MSA and characterize progression rates.
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