1. Department of Neurology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
2. Parkinson’s Disease Research, Education and Clinical Center, Philadelphia VA Medical Center, Philadelphia, PA, USA
3. Department of Biostatistics and Epidemiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
4. Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
5. Leonard Davis Institute of Health Economics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA