1. California Pacific Medical Center Research Institute, San Francisco, CA, USA
2. Department of Epidemiology, School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
3. Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
4. Geriatric Research Education and Clinical Center (GRECC), VA Health Care System, Palo Alto, CA, USA
5. Center for Care Delivery and Outcomes Research, VA Health Care System, Minneapolis, MN, USA
6. Department of Medicine, University of Minnesota, USA
7. Oregon Health and Science University, Portland, OR, USA
8. Department of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA