1. Department of Pediatrics, Boston Medical Center, Boston University School of Medicine, Boston, Massachusetts, USA.
2. Department of Emergency Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
3. Department of Emergency Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.
4. Department of Emergency Medicine, Boston Medical Center, Boston, Massachusetts, USA.
5. Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA.
6. Department of Health Law, Policy and Management, Boston University School of Public Health, Boston, Massachusetts, USA.