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Redefining the Multiple Sclerosis Severity Score (MSSS): The effect of sex and onset phenotype
Yuan Zhou1, Suzi B Claflin1, Jim Stankovich2
1Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS, Australia.
Background:
The Multiple Sclerosis Severity Score (MSSS) is a widely used measure of the disability progression rate. However, the global MSSS may not be the best basis for comparison between all patient groups.
Objective:
We evaluated sex-specific and onset phenotype-specific MSSS matrices to determine if they were more effective than the global MSSS as a basis for comparison within these subsets.
Methods:
Using a large international dataset of multiple sclerosis (MS) patient records and the original MSSS algorithm, we constructed global, sex-specific and onset phenotype-specific MSSS matrices. We compared matrices using permutation analysis.
Results:
Our final dataset included 30,203 MS cases, with 28.9% males and 6.5% progressive-onset cases. Our global MSSS matrix did not differ from previously published data (p > 0.05). The progressive-onset-specific matrix differed significantly from the relapsing-onset-specific matrix (p < 0.001), with lower MSSS attributed to cases with the same Expanded Disability Status Score (EDSS) and disease duration. When evaluated with a simulation, using an onset-specific MSSS improved statistical power in mixed cohorts. There were no significant differences by sex.
Conclusion:
The differences in the disability accrual rate between progressive- and relapsing-onset MS have a significant effect on MSSS. An onset-specific MSSS should be used when comparing the rate of disability progression among progressive-onset cases and for mixed cohorts.
Insights
The Multiple Sclerosis Severity Score (MSSS) is a disability progression measure. An onset-specific MSSS is more effective for comparing progressive-onset multiple sclerosis (MS) cases and mixed cohorts than a global MSSS.
Area of Science:
- Neurology
- Clinical Research
- Biostatistics
Background:
- The Multiple Sclerosis Severity Score (MSSS) is a standard metric for assessing disability progression in multiple sclerosis (MS).
- Global MSSS may limit accurate comparisons across diverse MS patient subgroups.
Purpose of the Study:
- To evaluate the efficacy of sex-specific and onset phenotype-specific MSSS matrices compared to the global MSSS.
- To determine if tailored MSSS matrices offer a better basis for comparison within specific MS patient subsets.
Main Methods:
- Construction of global, sex-specific, and onset phenotype-specific MSSS matrices using a large international MS patient dataset and the original MSSS algorithm.
- Comparison of constructed MSSS matrices via permutation analysis.
Main Results:
- The progressive-onset-specific MSSS matrix significantly differed from the relapsing-onset-specific matrix (p < 0.001).
- Onset-specific MSSS demonstrated improved statistical power in mixed cohorts during simulation.
- No significant differences in MSSS were observed between sexes.
Conclusions:
- Disability accrual rates differ significantly between progressive- and relapsing-onset MS, impacting MSSS.
- Onset-specific MSSS is recommended for comparing disability progression rates in progressive-onset MS and mixed cohorts.
