ABSTRACT
Measuring impairment and disability for the purpose of patient care differs from evaluating the impact of therapies in clinical trials. In the former, we are focused on the individual patient, with the goal of good care to prevent problems, alleviate suffering, and to have an impact on the course of disease. For these purposes, clinical assessments are needed to identify problems, document the course of the disease, provide etiological clues, and evaluate therapeutic efficacy. Because of complexity of the disease process in multiple sclerosis (MS) and the breadth of clinical consequences, clinical tools for MS can be effectively applied only by a skilled and experienced clinician. Good clinical care can be viewed as a series of informal clinical trials by an astute clinician using single patients as the study population. Individualized treatment is central to patient care, and successful response is the goal for each and every patient. This continual ongoing trial is appropriate at the individual level but is generally not appropriate for experimental studies. Rather, for the purpose of evaluating the impact of therapies on impairment and disability, clinical measurements derived from a population of patients under a common protocol are needed with predefined outcomes. This chapter describes the measurement of impairment and disability for use in MS clinical trials from a population, rather than from a patient care perspective. Many concepts discussed here are relevant at the patient level, but the reader should be cognizant that optimal measures for clinical trials may differ significantly from evaluative methods for individual patient care.
