1. From the Department of Biostatistics and Epidemiology (D.N.K., D.J.W., C.C.B.), Leonard Davis Institute of Health Economics (D.J.W., C.C.B., M.T.M.), and Department of Neurology (M.T.M.), University of Pennsylvania, Philadelphia; Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA (B.G.C.); and Duke University School of Medicine, Duke University, Durham, NC (C.S.W.).