1. Department of Preventive Medicine and Biometrics, University of Colorado at Denver and Health Sciences Center, Denver, Colorado.
2. Division of Health Care Policy and Research, Department of Medicine, University of Colorado at Denver and Health Sciences Center, Aurora, Colorado.
3. Nebraska Center for Rural Health Research, and Department of Preventive and Societal Medicine, University of Nebraska Medical Center, Omaha, Nebraska.
4. Department of Anthropology and Sociology, Eastern Oregon University, LaGrande, Oregon.