Mixed Race Studies

Taking race out of the equation in measuring women’s risk of osteoporosis and fractures

UCLA Newsroom
University of California, Los Angeles
2012-10-18

Enrique Rivero

For women of mixed racial or ethnic backgrounds, a new method for measuring bone health may improve the odds of correctly diagnosing their risk of osteoporosis and bone fractures, according to a UCLA-led study.

Currently, assessing osteoporosis and the risk of fractures from small accidents like falls requires a bone density scan. But because these scans don’t provide other relevant fracture-related information, such as bone size and the amount of force a bone is subjected to during a fall, each patient’s bone density is examined against a national database of people with the same age and race or ethnicity.

This approach, however, doesn’t work for people of mixed race or ethnicity because comparison databases can’t account for mixed heritage. A similar problem exists for those from smaller racial or ethnic groups for which there are not comparison databases.

“All the current ways of determining your risk for fractures require knowing your race and ethnicity correctly, and they ignore the fact that racial and ethnic groups are not homogenous,” said study co-author Dr. Arun Karlamangla, a professor of medicine in the geriatrics division at the David Geffen School of Medicine at UCLA. “It also flies in the face of the current reality in Southern California, where so many people are of mixed ethnicity.”

Given that osteoporosis and hip fractures are leading causes of injury in older people, alternative means of measuring risk are needed. Now, a UCLA-led team of researchers has found a way of assessing risk without knowledge of a person’s race or ethnicity. The method involves combining bone mineral density measures with body size and bone size to create composite bone strength indices.

The findings are published in the October issue of the Journal of Clinical Endocrinology and Metabolism…

…”The importance of bone size to fracture risk has been recognized by engineers and radiologists for some years now,” said the study’s lead investigator, Dr. Shinya Ishii, who started the research while a fellow in the UCLA Division of Geriatrics and is now at the University of Tokyo. “But no one, until now, has combined bone density, which is the traditional measure of osteoporosis, with bone size and body size to get at a more uniform way of assessing osteoporosis that applies across racial lines and does away with the need to know the person’s race or racial mixture.“…

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Fracture Risk Assessment without Race/Ethnicity Information

The Journal of Clinical Endocrinology & Metabolism
Volume 97, Number 10 (2012-10-01)
pages 3593-3602
DOI: 10.1210/jc.2012-1997

Shinya Ishii
Department of Geriatric Medicine (S.I.)
Graduate School of Medicine
University of Tokyo

Gail A. Greendale
David Geffen School of Medicine
University of California, Los Angeles

Jane A. Caule
Graduate School of Public Health
University of Pittsburgh

Carolyn J. Crandall
David Geffen School of Medicine
University of California, Los Angeles

Mei-Hua Huang
David Geffen School of Medicine
University of California, Los Angeles

Michelle E. Danielson
Graduate School of Public Health
University of Pittsburgh

Arun S. Karlamangla
David Geffen School of Medicine
University of California, Los Angeles

Context: Dual-energy x-ray absorptiometry-derived bone mineral density (BMD) does not explain interracial differences in fracture risk; thus, BMD-based fracture risk assessment requires patient race/ethnicity information and ethnicity-specific BMD reference databases.

Objective: The objective of the study was to investigate whether composite femoral neck strength indices, which integrate dual-energy x-ray absorptiometry-derived femoral neck size, femoral neck BMD, and body size, will allow fracture risk assessment without requiring race/ethnicity information.

Design: This was a prospective cohort study.

Setting and Participants: A total of 1940 community-dwelling women aged 42–53 yr from four race/ethnicity groups (968 Caucasian, 512 African-American, 239 Japanese, and 221 Chinese) were followed up for 9 yr.

Outcome Measurements: Self-reported, nondigital, noncraniofacial fractures were measured.

Results: Two hundred and two women (10.4%) sustained fractures and 82 (4.3%) had minimum-trauma fractures. Each sd increment in any of the strength indices was associated with a 34–41% reduction in fracture hazard over 9 yr (each P < 0.001). Race/ethnicity predicted fracture hazard independent of BMD (P = 0.02) but did not predict fracture hazard independent of any of the composite indices (P = 0.11–0.22). Addition of race/ethnicity did not improve risk discrimination ability of the strength indices, but did significantly improve the discrimination ability of BMD. The discrimination ability of BMD with race/ethnicity was not statistically different from that of any of the strength indices without race/ethnicity.

Conclusions: Composite strength indices of the femoral neck can predict fracture risk without race/ethnicity information as accurately as bone mineral density does in combination with race/ethnicity information and therefore would allow risk prediction in people of mixed race/ethnicity and in groups without a BMD reference database.

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