1. Department of Emergency Medicine, University of Iowa, Iowa City, IA, USA
2. Department of Epidemiology, Colleges of Medicine and Public Health, University of Iowa, Iowa City, IA, USA
3. Department of Health Management and Policy, College of Public Health, University of Iowa, Iowa City, IA, USA
4. Department of Anesthesia, Division of Critical Care, University of Iowa, Iowa City, IA, USA