1. Department of Epidemiology, Brown University School of Public Health, Providence, RI, USA
2. Division of Epidemiology, University of California Berkeley School of Public Health, Berkeley, CA, USA
3. Department of Emergency Medicine, Boston Medical Center Injury Prevention Center and Boston University School of Medicine, Boston, MA, USA
4. Department of Emergency Medicine, The Warren Alpert School of Medicine of Brown University, Rhode Island Hospital, Providence, RI, USA
5. Department of Pediatrics, Boston Medical Center, Boston, MA, USA
6. Department of Pediatrics, Division of General Pediatrics, Boston University School of Medicine, Boston, MA, USA