1. Division of Primary Care and Population Health, Stanford University School of Medicine, Stanford, CA 94305, USA
2. Division of Endocrinology, Gerontology and Metabolism, Stanford University School of Medicine, Stanford, CA 94305, USA
3. Division of Hematology, Stanford University School of Medicine, Stanford, CA 94305, USA
4. Veterans Affairs Palo Alto Health Care System, 3801 Miranda Avenue, Palo Alto, CA 94304, USA
5. Quantitative Sciences Unit, Stanford University School of Medicine, Stanford, CA 94305, USA
6. Division of General Medical Disciplines, Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA