1. University of Iowa, Department of Emergency Medicine, Carver College of Medicine, 200 Hawkins Drive, 1008 RCP, Iowa City, IA 52242, USA
2. University of Iowa, Department of Epidemiology, College of Public Health, 145 N. Riverside Drive, 400 CPHB, Iowa City, IA 52242, USA
3. Nationwide Children's, Center for Injury Research and Policy, 700 Children's Dr., RBIII-WB5403, Columbus, OH 43205, USA
4. University of Iowa, Injury Prevention Research Center, 2190 Westlawn, Iowa City, IA 52242, USA
5. University of Iowa, College of Public Health, Department of Occupational and Environmental Health, 145 N. Riverside Drive, S143 CPHB, Iowa City, IA 52242, USA