Disability Expectancy Table Useful for Patients and Clinicians

Patients with multiple sclerosis do not have access to easy-to-use references of disability outcomes that would allow them to compare their disability to others with similar duration of disease. The Global Multiple Sclerosis Severity Score (MSSS), a representation of disability outcomes as a table of mean ranks of Expanded Disability Status Scale (EDSS) scores in patients with comparable disease duration, is useful for epidemiologic studies. However, as a reference for patients and clinicians, the utility of the MSSS is limited by the requirement for assessment of EDSS score by trained clinicians as well as a lack of a simple, intuitive interpretation, according to researchers.

To develop a patient- and clinician-friendly reference table of disability outcomes in MS, the researchers created the Disability Expectancy Table (DET). They reported on their efforts in Neurology^®, the official scientific journal of the American Academy of Neurology [published online ahead of print on February 20, 2013, 10.1212/wnl.0b013e3182872855].

The DET was created utilizing the North American Research Committee on Multiple Sclerosis (NARCOMS) Registry that collects disability data from patients with MS. The registry uses a validated, 9-point Patient-Determined Disease Steps (PDDS) scale. The DET displays maximum ranks of PDDS scores for disease duration of 0 to 45 years and allows easy determination of how a patient’s disability compares to others with the same duration of disease.

The DET also tabulates mean ranks of PDDS scores for each year of disease, making the DET more relevant for clinical researchers, the authors said. “The mean ranks, Patient-Determined Multiple Sclerosis Severity Scores (P-MSSS) stand in the same relation to PDDS as MSSS does to EDSS. P-MSSS does not require clinician input and could become a practical and cost-effective alternative outcome measure for epidemiologic research,” they noted.

In June 2011, the NARCOMS Registry included records on 35,930 participants from the United States. After applying exclusion criteria, the reference cohort consisted of 27,918 NARCOMS registrants, each contributing only their enrollment PDDS score to the analysis. Of the final cohort, 72.7% were female, 90.1% were white, mean age at symptom onset was 30.1 years, age at diagnosis was 37.3 years, and 52.0% (of 11,790 respondents who answered the question) were taking immunomodulatory therapies.

The DET and P-MSSS provide a detailed overview of disability outcomes in a large cohort of patients with MS over a 45-year period. In the first year of disease, 15% of patients reported need of ambulatory aid and 4% needed bilateral assistance or worse. After 45 years, 76% of patients required ambulatory aid and 52% needed bilateral assistance or worse.

The proportion of patients who reported minimal or no interference in daily activities (PDDS £1) declined from 63% in the first year to 8% after 45 years of disease.

In conclusion, the researchers stated, “The DET represents a uniquely detailed overview of disability outcomes in a large MS cohort over several decades of disease. For patients with MS, the DET affords an opportunity to determine how their disability compares to others with similar disease duration and so provides context for more informed treatment decision-making, which is becoming increasingly complex with expansion of the therapeutic armamentarium in MS. For the clinical researcher, P-MSSS may prove useful as a practical and cost-effective outcome measure for comparing disability across different populations, and tracking disease progression and response to treatments in patient cohorts.”