The Sonya Slifka Longitudinal Multiple Sclerosis Study: methods and sample characteristics.

The Sonya Slifka Longitudinal Multiple Sclerosis Study follows a population-based cohort of approximately 2000 people with multiple sclerosis (MS) to study demographic and clinical characteristics, course of illness, utilization and cost of health services, provider characteristics, use of MS specialists and disease modifying agents, and neurologic, economic and psychosocial outcomes. This report describes the study methodology, presents baseline demographic and clinical data, and evaluates the representativeness of the sample. A stratified random sample of persons with established and recently-diagnosed MS selected from the National Multiple Sclerosis Society (NMSS) mailing lists was supplemented with recently-diagnosed patients recruited through systematic nationwide outreach.