Disability measurement in Multiple Sclerosis patients 55 years and older: What is the Expanded Disability Status Scale really telling clinicians?

Abstract Background The Expanded Disability Status Scale (EDSS) measures disease progression in Multiple Sclerosis (MS). EDSS changes are assumed to be due to worsening MS-related disability. Strict interpretation of this premise may include some normal findings as abnormal, inflating the disability score. Further, determining the cause of neurological symptoms can be difficult in an older population with comorbid illness and polypharmacy. Objective To examine the association between EDSS, age, comorbidities and polypharmacy. Methods 106 people, 55 years and older, with and without MS were administered the EDSS and a validated comorbidity questionnaire. Polypharmacy was also assessed. Results Median EDSS scores were 6.0 in people with MS and 3.0 in people without MS. No participant in our cohort had an EDSS of 0. Higher EDSS scores were associated with older age and more polypharmacy. Pyramidal and cerebellar functional systems accounted for the largest percentage of unique variance between groups. Conclusion Older individuals with and without MS demonstrated significant disability on the EDSS. These findings indicate that EDSS scores may be partially due to factors other than MS. Our understanding of disease course and disability may benefit from the development of normative EDSS scores to correct for these factors.