1. Division of Emergency Medicine, Duke University School of Medicine, Durham, North Carolina
2. Kaiser Permanente South San Francisco, South San Francisco, California
3. Department of Medicine, Durham VA Medical Center, Durham, North Carolina
4. Department of Medicine, Duke University Health System, Durham, North Carolina
5. Department of Emergency Medicine and Rocky Mountain Poison and Drug Center, Denver Health, Denver, Colorado
6. Department of Emergency Medicine, University of Colorado School of Medicine, Aurora