1. Center for Injury Research and Prevention, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
2. Division of Emergency Medicine, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
3. Department of Biostatistics, Epidemiology, and Informatics, University of Pennsylvania, Philadelphia, Pennsylvania, USA
4. School of Nursing, University of Pennsylvania, Philadelphia, Pennsylvania, USA
5. Sports Medicine and Performance Center, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA