Clinical scoring methods for multiple sclerosis.

Multiple sclerosis (MS) clinical rating scales are used to classify the degree of neurological dysfunction and to plan treatment measures. In clinical trials, rating scales are used to monitor clinical course and response to experimental therapies. Selection of the appropriate clinical rating scale is determined by the nature of the research question (e.g., disability, impairment, handicap). The Expanded Disability Status Scale (EDSS, an impairment scale) has been the most widely used clinical rating method in natural history studies and clinical trials. The EDSS has the advantage of familiarity, yet is difficult to use consistently between evaluators. In the mid and higher ranges, the EDSS is relatively insensitive to clinical changes that do not impair gait. Evaluator unblinding may invalidate the clinical assessment of response to treatment. Additional work is needed to develop clinical and laboratory (imaging) measures of MS disease activity that will be objective, reliable, sensitive, responsive, and valid. Recent comparative studies have demonstrated that serial magnetic resonance imaging (MRI) studies are 7- to 10-fold more sensitive than clinical methods in detecting subclinical evidence of apparent MS disease activity. Widespread acceptance of MRI as a primary trial outcome measure awaits the results of studies designed to determine whether MRI findings accurately reflect irreversible pathological changes and predict future disability.