1. Department of Health Services Policy and Management, Arnold School of Public Health, University of South Carolina, Columbia, South Carolina, USA.
2. Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, Columbia, South Carolina, USA.
3. Rural and Minority Health Research Center, Columbia, South Carolina, USA.
4. Department of Health Services Research and Administration, College of Public Health, University of Nebraska Medical Center, Omaha, Nebraska, USA.