1. Department of General Internal Medicine, University of Colorado Anschutz School of Medicine, Aurora, Colorado , USA
2. School of Social and Behavioral Sciences, Mercy College, Dobbs Ferry, New York , USA
3. University of Southern California, Leonard David School of Gerontology, Los Angeles, California , USA
4. Department of OB-GYN, New York University Grossman School of Medicine, New York, New York , USA
5. Department of Sociology and Gerontology, Miami University, Oxford, Ohio , USA