1. From the Division of Pediatric Emergency Medicine, Department of Pediatrics, Emory University School of Medicine and the Children's Healthcare of Atlanta, Atlanta, Georgia;
2. Division of Pediatric Emergency Medicine, Department of Pediatrics, University of Pennsylvania School of Medicine and Children's Hospital of Philadelphia, Philadelphia, Pennsylvania; and
3. Center for Injury Control, Rollins School of Public Health, and the Department of Emergency Medicine, Emory University School of Medicine, Atlanta, Georgia.