1. From the Departments of Neurology, Epidemiology, and Social Medicine, Albert Einstein College of Medicine, Bronx, NY
2. Innovative Medical Research, Stamford, Conn and Hunt Valley, Md
3. Department of Epidemiology, Johns Hopkins School of Public Health, Baltimore, Md
4. Diamond Headache Clinic, Chicago, Ill
5. Strategic Insights, Inc, Chapel Hill, NC