Multiple Sclerosis Severity Score

TLDR

There is no consensus method for determining progression of disability in multiple sclerosis patients when only a single assessment is available. Using two large longitudinal databases, the authors devised the Multiple Sclerosis Severity Score (MSSS), an algorithm that maps EDSS to the distribution of disability among patients with comparable disease durations, applied it to nearly 10,000 patients from 11 countries to create a Global MSSS, and simulated genetic effects to compare methods. Cross‑sectional EDSS measurements taken after the first year accurately reflect overall disease severity, and the MSSS outperforms other methods in detecting differing progression rates, enabling group comparisons via a Global MSSS reference table, though disease fluctuation limits its use as a predictor for individual future disability.

Abstract

<b>Background: </b> There is no consensus method for determining progression of disability in patients with multiple sclerosis (MS) when each patient has had only a single assessment in the course of the disease. <b>Methods: </b> Using data from two large longitudinal databases, the authors tested whether cross-sectional disability assessments are representative of disease severity as a whole. An algorithm, the Multiple Sclerosis Severity Score (MSSS), which relates scores on the Expanded Disability Status Scale (EDSS) to the distribution of disability in patients with comparable disease durations, was devised and then applied to a collection of 9,892 patients from 11 countries to create the Global MSSS. In order to compare different methods of detecting such effects the authors simulated the effects of a genetic factor on disability. <b>Results: </b> Cross-sectional EDSS measurements made after the first year were representative of overall disease severity. The MSSS was more powerful than the other methods the authors tested for detecting different rates of disease progression. <b>Conclusion: </b> The Multiple Sclerosis Severity Score (MSSS) is a powerful method for comparing disease progression using single assessment data. The Global MSSS can be used as a reference table for future disability comparisons. While useful for comparing groups of patients, disease fluctuation precludes its use as a predictor of future disability in an individual.