Abstract | CONTEXT: We hypothesize that endogenous sex steroids are associated with fracture risk independent of race/ethnicity.

DESIGN AND SETTING: We performed a nested case-control study within the prospective Women’s Health Initiative Observational Study (WHI-OS). Incident non-spine fractures were identified in 381 Black, 192 Hispanic, 112 Asian, and 46 Native American women over an average of 8.6 years. A random sample of 400 White women who experienced an incident fracture was chosen. One control was selected per case and matched on age, race/ethnicity, and blood draw date. Bioavailable estradiol (BioE2), testosterone (BioT) and sex hormone-binding globulin (SHBG) were measured using baseline fasting serum. Conditional logistic regression models calculated the odds ratio (OR) and 95% confidence interval (CI) of fracture across tertiles of hormone.

RESULTS: In multivariable and race/ethnicity adjusted models, higher BioE2 (>8.25 pg/ml) and higher BioT (>13.3 pg/ml) were associated with decreased risk of fracture, OR=0.65 (0.50-0.85), p trend=0.001 and OR=0.76 (0.60-0.96), p trend=0.02, respectively. The interaction term between race/ethnicity and either BioE2 or BioT was not significant. There was no association between SHBG and fracture risk. In models stratifying by race/ethnicity, higher BioE2 was associated with a lower risk of fracture in both White women, OR=0.56 (0.36-0.87) and Black women, OR=0.61 (0.39, 0.96). Higher BioT was associated with a significantly lower fracture risk in only Black women, OR=0.65 (0.43-0.97).

CONCLUSION: Serum BioE2 and BioT are associated with fracture risk in older women irrespective of race/ethnicity, independent of established risk factors for fracture.

Jane A. Cauley Michelle E. Danielson Guru Rajesh Jammy Doug C. Bauer Rebecca Jackson Jean Wactawski-Wende Rowan T. Chlebowski Kristine E. Ensrud Robert Boudreau

(2017) jc.2016-3589. DOI: https://doi.org/10.1210/jc.2016-3589

Published: 25 January 2017

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