1. Department of Health Management and Policy and College of Public Health, University of Iowa, Iowa City, Iowa, USA.
2. Department of Biostatistics, College of Public Health, University of Iowa, Iowa City, Iowa, USA.
3. Department of Health Services Policy & Management, Arnold School of Public Health, University of South Carolina, Columbia, South Carolina, USA.
4. Office of Rural Health Policy, Health Resources and Services Administration, Rockville, Maryland, USA.
5. Department of Epidemiology, College of Public Health, University of Iowa, Iowa City, Iowa, USA.
6. Department of Emergency Medicine and Division of Critical Care, College of Medicine, University of Iowa, Iowa City, Iowa, USA.
7. Department of Anesthesia, Division of Critical Care, College of Medicine, University of Iowa, Iowa City, Iowa, USA.