Cost of multiple sclerosis by level of disability: a review of literature.

We performed a review of the economic literature to identify what is known about the relationship between Expanded Disability Status Scale (EDSS) categories and cost of multiple sclerosis (MS). We sought cohort studies of patients with multiple sclerosis that described the costs attributed to each EDSS score and utilized specific inclusion criteria for the selection of 10 studies. We found that both direct and indirect costs rise continuously with increasing EDSS category, and this rise is qualitatively exponential. The rise in indirect costs appears at lower EDSS scores. The cost of a relapse occurring in any given EDSS category exceeds that associated with that particular EDSS category. Few studies comprehensively assessed the entire spectrum of the costs, and much of the literature is based on EDSS categories in coarse groupings. In spite of several variations between studies, one important conclusion that we can draw is that rise in cost is positively correlated to scores on the EDSS categories, and therefore agents with a capacity to prevent or arrest the rate of MS progression may affect the overall cost of MS.