© 2001 by Taylor & Francis Group, LLC. I. INTRODUCTION Quantifying the clinical impact of multiple sclerosis (MS) is necessary for a number of reasons. Clinical assessment tools are needed for patient care. If not for clinical outcome assessments, how would a neurologist determine disease severity or the effect of treatment? Clinical assessment tools are also indispensable for judging experimental therapies. If not for clinical assessment tools, how would investigators measure the effectiveness of an intervention?.