1. Department of Emergency Medicine, Massachusetts General Hospital, Boston, MA (REC, CAC);
2. National Registry of Emergency Medical Technicians, Columbus, OH (REC, MKR, ARP);
3. Division of Epidemiology, The Ohio State University College of Public Health, Columbus, OH (REC, SEA, KEL, ARP);
4. Division of Biostatistics, The Ohio State University College of Public Health, Columbus, OH (BL);
5. Division of Health Behavior and Health Promotion, The Ohio State University College of Public Health, Columbus, OH (MKR);
6. Department of Emergency Medicine, The Ohio State University Wexner Medical Center, Columbus, OH (ARP)