Intentional and Unintentional Weight Loss Increase Bone Loss and Hip Fracture Risk in Older Women

Authors

  • Kristine E. Ensrud MD, Mph,

    1. From theDepartment of Medicine and Center for Chronic Disease Outcomes Research, VA Medical Center, Minneapolis, Minnesota
    2. Division of Epidemiology, School of Public Health, University of Minnesota, Minneapolis, Minnesota
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  • Susan K. Ewing MS,

    1. Department of Epidemiology and Biostatistics, University of California at San Francisco, San Francisco, California
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  • Katie L. Stone PhD,

    1. Department of Epidemiology and Biostatistics, University of California at San Francisco, San Francisco, California
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  • Jane A. Cauley DrPH,

    1. Department of Epidemiology, University of Pittsburgh, Pittsburgh, Pennsylvania.
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  • Paula J. Bowman MPH,

    1. Division of Epidemiology, School of Public Health, University of Minnesota, Minneapolis, Minnesota
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  • Steven R. Cummings MD,

    1. Department of Epidemiology and Biostatistics, University of California at San Francisco, San Francisco, California
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  • for the Study of Osteoporotic Fractures Research Group

    1. From theDepartment of Medicine and Center for Chronic Disease Outcomes Research, VA Medical Center, Minneapolis, Minnesota
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  • Supported by Grants AG05407, AR35582, AG05394, AR35584, and AR35583 from the Public Health Service. Funded by the National Institutes of Health, which had no role in the collection, analysis, or interpretation of the data or in the decision to submit the paper for publication.

Address correspondence to Kristine E. Ensrud, MD, MPH, Department of Medicine (111–0), VA Medical Center, One Veterans Drive, Minneapolis, MN 55417. E-mail: ensru001@tc.umn.edu

Abstract

Objectives: To test the hypothesis that unintentional weight loss increases the rate of bone loss and risk of hip fracture more than intentional weight loss.

Design: Prospective cohort study.

Setting: Four communities within the United States.

Participants: Six thousand seven hundred eighty-five elderly white women with measurement of weight change and assessment of intention to lose weight.

Measurements: Weight change between baseline and fourth examinations (average 5.7 years between examinations) and assessment of intention to lose weight. Weight loss was defined as a decrease of 5% or more from baseline weight, stable weight was defined as less than a 5% change from baseline weight, and weight gain was defined as an increase of 5% or more from baseline weight. Rate of change in bone mineral density at the hip between fourth and sixth examinations (average 4.4 years between examinations) was measured using dual-energy x-ray absorptiometry. Incident hip fractures occurring after the fourth examination until June 1, 2001 (average follow-up 6.6 years) was confirmed using radiographic reports.

Results: The adjusted average rate of decline in total hipbone density steadily increased from −0.52% per year in women with weight gain to −0.68% per year in women with stable weight to −0.92% per year in women with weight loss (P-value for trend <.001). Higher rates of hip-bone loss were observed in women with weight loss irrespective of body mass index (BMI) or intention to lose weight. During follow-up of an average 6.6 years after the fourth examination, 400 (6%) of the cohort suffered a first hip fracture. Women with weight loss had 1.8 times the risk (95% confidence interval (CI)=1.43–2.24) of subsequent hip fracture as those with stable or increasing weight. The association between weight loss and increased risk of hip fracture was consistent across categories of BMI and intention to lose weight. Even voluntary weight loss in overweight women with a BMI of 25.9 kg/m2 (median) or greater increased the risk of hip fracture (multivariate hazard ratio=2.48, 95% CI=1.33–4.62).

Conclusion: Older women who experience weight loss in later years have increased rates of hip-bone loss and a two-fold greater risk of subsequent hip fracture, irrespective of current weight or intention to lose weight. These findings indicate that even voluntary weight loss in overweight elderly women increases hip fracture risk.

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