1. From the Department of Emergency Medicine, School of Medicine (D.L.M.), and the Department of Epidemiology, School of Public Health (W.R.), University of North Carolina, Chapel Hill; Marshfield, Clinic (K.M.), Marshfield, Wis; the Department of Emergency Medicine, School of Medicine (C.S.), University of Michigan, Ann Arbor; and Genentech Inc (S.H.), South San Francisco, Calif.