1. Department of Epidemiology; University of Pittsburgh; Pittsburgh PA USA
2. Centers for Disease Control and Prevention; Atlanta GA USA
3. California Pacific Medical Centre; San Francisco CA USA
4. Department of Medicine; University of Minnesota; Minneapolis MN USA
5. Division of Epidemiology and Community Health, School of Public Health; University of Minnesota; Minneapolis MN USA
6. Center for Chronic Disease Outcomes Research; VA Health Care System; Minneapolis MN USA
7. Geriatric Education and Clinical Center; VA Health Care System; Minneapolis MN USA
8. Bone and Mineral Unit; Oregon Health and Science University; Portland OR USA