1. Department of Neurology; Washington University School of Medicine; 660 South Euclid Avenue, Campus Box 8111 St. Louis Missouri 63110
2. School of Public Health; Faculty of Health Sciences; University of the Witwatersrand; 7 York Road Parktown 2193 South Africa
3. Center for Health Outcomes Research and Education; Department of Pharmacy Practice; St. Louis College of Pharmacy; 4588 Parkview Place St. Louis Missouri 63110
4. Department of Neurology; University of Pennsylvania Perelman School of Medicine; 423 Guardian Drive Philadelphia Pennsylvania 19104
5. Department of Biostatistics, Epidemiology and Informatics; University of Pennsylvania Perelman School of Medicine; 423 Guardian Drive Philadelphia Pennsylvania 19104
6. The Center for Pharmacoepidemiology Research and Training; University of Pennsylvania Perelman School of Medicine; 423 Guardian Drive Philadelphia Pennsylvania 19104