1. Department of Medicine, Keck School of Medicine, University of Southern California , Los Angeles, California , USA
2. Department of Population and Public Health Sciences, Keck School of Medicine, University of Southern California , Los Angeles, California , USA
3. Department of Medical Education, Keck School of Medicine, University of Southern California , Los Angeles, California , USA
4. LAC+USC Medical Center, Department of Health Services of Los Angeles County , Los Angeles, California , USA