1. Department of Pediatrics and
2. Division of Neonatology, Department of Pediatrics,
3. Center for Outcomes Research, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania;
4. Senior Scholar, Leonard Davis Institute of Health Economics, University of Pennsylvania, Philadelphia, Pennsylvania
5. Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania; and
6. Department of Emergency Medicine, and