Fracture Risk AssessmentAdjusting Hip Fracture Probability in Men and Women Using Hip Axis Length: the Manitoba Bone Density Database
Introduction
Hip fractures are associated with decreased quality of life, excess mortality that exceeds 20% in the initial year, and a large societal economic burden 1, 2, 3, 4. Accurately identifying individuals at greatest risk for hip fracture should optimally lead to targeted intervention to reduce that risk. In addition to nonpharmacological interventions, such as falls prevention, optimization of calcium and vitamin D intake, and exercise programs that promote strength and balance (5), approved pharmacological agents have been shown to reduce hip fractures by about 40% in appropriately selected individuals (6).
Bone mineral density (BMD) measured from dual-energy X-ray absorptiometry (DXA) is widely used to assess hip fracture risk as meta-analyses have shown that each standard deviation (SD) reduction in femoral neck BMD increases hip fracture risk by approximately 2.6-fold 7, 8. Accordingly, BMD of the proximal femur measured by DXA has been designated the reference methodology for the densitometric diagnosis of osteoporosis based on a T-score of −2.5 or lower (9). Notwithstanding the strength of the BMD-fracture relationship, DXA does not capture all aspects of femoral strength or hip fracture risk, and most hip fractures occur in individuals who have a BMD above the osteoporotic threshold 8, 10, 11, 12. The World Health Organization Collaborating Centre Fracture Risk Assessment Tool (FRAX) estimates individual 10-yr probability of hip fracture and major osteoporotic fracture using clinical risk factors derived from meta-analyses and (optionally) femoral neck BMD (13). FRAX has been shown to improve fracture risk assessment over BMD alone in derivation and validation cohorts (14). However, FRAX does not consider non-BMD parameters related to skeletal geometry and strength 15, 16.
Hip axis length (HAL) is conventionally defined as the distance from the base of the greater trochanter to the inner pelvic brim. This measure is associated with hip fracture risk in women; comparable data in men are sparse 17, 18, 19, 21. We have previously shown that longer HAL was an independent risk factor for hip fracture in women after adjustment for BMD and FRAX hip fracture probability (21). The present study was performed to test if HAL had a similar independent effect on hip fracture risk in men and to derive a simple adjustment for FRAX hip fracture probability using HAL to improve clinical risk assessment.
Section snippets
Study Population
We identified all men and women aged 40 yr and older with health care coverage in the province of Manitoba, Canada, who underwent baseline bone density measurement of the proximal femur with a single fan-beam scanner configuration (Prodigy; GE Healthcare, Madison, WI, USA). For those with more than 1 eligible set of measurements, only the first record was included. In Manitoba, health services are provided to virtually all residents and recorded through a single public health care system. DXA
Results
Baseline characteristics of the cohort, comprising 4738 men and 50,420 women aged 40 yr and older, are summarized in Table 1. Men were slightly older than women (mean age: 66.0 vs 64.3 yr, p < 0.001), femoral neck BMD was higher for men (mean: −1.1 vs −1.4 for women, p < 0.001), whereas hip fracture probability was similar (p = 0.827). Mean HAL was greater in men than women (121.3 vs 104.7 mm, p < 0.001).
During mean follow-up of 6.2 yr, 70 (1.5%) men and 1020 (2.0%) women developed incident hip
Discussion
We have previously shown that longer HAL was a BMD and FRAX-independent risk factor for hip fracture in women (21). The present study provides complementary data in men and confirms that longer HAL is also a risk factor for hip fracture in men. Furthermore, this risk is independent of hip fracture probability estimated with the FRAX algorithm and does not differ according to sex. As a result, a simple bilinear adjustment for FRAX hip fracture probability based on HAL applicable to both men and
Acknowledgments
We are indebted to Manitoba Health for providing data (HIPC File No. 2011/2012-31). The results and conclusions are those of the authors, and no official endorsement by Manitoba Health is intended or should be inferred. This article has been reviewed and approved by the members of the Manitoba Bone Density Program Committee.
Details of contributors and guarantor: Authors substantially contributed to: conception, design, and analysis (William D. Leslie) and interpretation of data (all authors);
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2021, Endocrinology and Metabolism Clinics of North AmericaCitation Excerpt :The ISCD has determined that longer HAL is associated with greater hip fracture risk in postmenopausal women, and that other hip geometry parameters (eg, cross-sectional area, cross-sectional moment of inertia, neck shaft angle) should not be used to assess hip fracture risk.58 An analysis of the Manitoba Bone Density Database found a relative increase in hip fracture probability of 4.7% for every millimeter that HAL is above the sex-specific average for both men and women.59 This risk is independent of BMD and FRAX probability.
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2019, Journal of Clinical DensitometryCitation Excerpt :Prolonged glucocorticoid use (≥3 mo in the year prior to BMD test) was captured in the province-wide retail pharmacy database system. We also considered HAL since this is a geometric measurement derived from hip DXA that predicts hip fracture risk independent of BMD and FRAX score (27,28). Continuous variables were reported as means with standard deviations, and counts with percentages.
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Disclosure: The authors have nothing to disclose related to this work.