Axial Bone Mass in Older Women

Axial Bone Mass in Older Women

For the Study of Osteoporotic Fractures Research Group* From the Portland Veterans Affairs Medical Center and Kaiser Permanente Center for Health Research, Portland, Oregon; University of California, San Francisco, Prevention Sciences Group, San Francisco, California; and University of Maryland, Baltimore, Maryland. Acknowledgments: The authors thank Kathy Linton for outstanding biostatistical support and Nancy Black for excellent manuscript preparation. Grant Support: By Public Health Service grants RO1-AG605407, RO1-AR35582, RO1-AG053904, RO1-AM35584, and RO1-AR35583. Requests for Reprints: Eric Orwoll, MD, Bone and Mineral Research Unit, Medical Service (111), Portland Veterans Affairs Medical Center, PO Box 1034, Portland, OR 97207. Current Author Addresses: Dr. Orwoll: Portland Veterans Affairs Medical Center, PO Box 1034, Portland, OR 97207

Abstract

Objective: To determine the anthropometric, historical, and lifestyle factors associated with bone mineral density (BMD) of the spine and proximal femur in older women.

Design: Cross-sectional analyses.

Setting: Four clinical centers in Baltimore, Maryland; Minneapolis, Minnesota; Portland, Oregon; and the Monongahela Valley, Pennsylvania.

Participants: 7963 ambulatory, nonblack women 65 years of age or older.

Measurements: Medical history was obtained by questionnaire and interview, and physical and anthropometric data were obtained by examination. Lumbar spine and proximal femoral BMDs were measured using dual-energy x-ray absorptiometry.

Results: The multivariable models could predict 21% and 25% of the difference between participants in BMD at the femoral neck and lumbar spine, respectively. Weight was most highly associated with BMD. Postmenopausal estrogen use and other indicators of total estrogen exposure were strongly associated with increased BMD. Use of diuretics (both thiazide and nonthiazide), activity levels and muscle strength, alcohol intake, and dietary calcium intake were associated with higher BMD. A family history of osteoporotic fracture was strongly associated with low BMD. European ancestry and blond hair, childbirth or breast feeding, a history of hyperthyroidism, and progestin use were not associated with axial BMD.

Conclusions: Weight is strongly associated with BMD. Estrogen exposure, physical activity, and calcium intake are also positively associated with BMD, whereas a family history of osteoporosis is associated with reduced BMD. These associations suggest ways to better identify risk for fracture.

*For members of the Study of Osteoporotic Fractures Research Group, see the Appendix.