| Affiliation: | 1. Division of General Internal Medicine, The Johns Hopkins University School of Medicine, , Baltimore, Maryland, USA;2. Department of Epidemiology, The Johns Hopkins Bloomberg School of Public Health, , Baltimore, Maryland, USA;3. Department of Obstetrics and Gynecology, University of North Carolina School of Medicine, , Chapel Hill, North Carolina, USA;4. Division of Research, Kaiser Permanente Northern California, , Oakland, California, USA;5. Division of Preventive Medicine, University of Alabama School of Medicine, , Birmingham, Alabama, USA |
