Population Dynamics of the Disability Status Scales for Multiple Sclerosis

Abstract

The Kurtzke Extended Disability Status Scale (EDSS) is commonly used to classify the severity of multiple sclerosis. It could also be used as a measure of treatment outcomes, but that would require a published database of the natural history of the disease with respect to rates of change among EDSS categories. We analyzed the cur rent literature and found only eleven reports documenting the rates of change of EDSS scores for individual patients. This time-dependent data did not correlate well with twenty-two reports of static distributions of patients along the series of EDSS categories. We conclude that the natural history of multiple sclerosis as measured by EDSS scores is not yet sufficiently documented to provide standards for uncon trolled studies of outcomes. Key Words: Kurtzke scale—EDSS—Multiple sclerosis— Population dynamics—Grading systems.