When to get your bone density measured -- that is the question

A new study provides doctors with guidelines on when to repeat bone mineral density (BMD) tests for their patients.

13 may 2009--International clinical guidelines on the matter are hazy, with different practices followed in different countries. For a serious condition like osteoporosis, affecting millions, it is important to establish clear protocols.

Professor Tuan Nguyen and Dr Nguyen Nguyen from the Garvan Institute of Medical Research, with PhD student Steve Frost from The University of Western Sydney, have updated fracture risk algorithms and created simple tables to guide clinicians. Their findings are now online in the prestigious Journal of Bone and Mineral Research.

"More than 50% of women and 60% of men who suffer a fracture do not have osteoporosis," said Professor Nguyen, who led the study.

"Fracture prevention treatment usually relies on the diagnosis of osteoporosis by bone density measurement. This does not help the people who are not osteoporotic but are at risk of fracture based on a combination of other risk factors, including age, history of personal fracture, and history of falls."

"There are varying opinions around the world on whether or not repeat bone density measurements can help prognosis of fracture. Our research suggests they can."

"Bone density is an important predictor of fracture, and it declines with advancing age. Each year, people lose 0.6 – 1.0% of their bone density."

"If someone has a BMD T score of -2.5 or lower, they have osteoporosis. If someone has a BMD T score of -2.4, they don't have osteoporosis now, but they could develop it within a year."

"So if a 70 year old woman showed a BMD T score of -2.4, it's logical that you would not re-schedule her for testing in 2 years."

"We think that it's vital to reschedule bone density measurements based on age and initial BMD."

The data for the work come from the world-renowned Dubbo Osteoporosis Epidemiology Study, where the bone health of a group of non-osteoporotic men and women was tracked for 18 years to see how many of them developed osteoporosis or sustained fractures.

Professor Nguyen and team developed a web-based fracture risk calculator last year, also based on Dubbo data.

"Our current model of prognoses, which predicts the risk of osteoporosis or fracture based on an individual's age and initial BMD, will eventually be incorporated into the online calculator and this additional element will make it even more powerful," said Nguyen.

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Paper nomograms and tables, incorporating the new calculations, are available to GPs from the Osteoporosis and Bone Biology Program by request.

Study finds link between hot flashes and lower bone density in women

07 may 2009 : UCLA researchers and colleagues analyzed data for 2,213 women between the ages of 42 and 52 who participated in the bone sub-study of the Study of Women's Health Across the Nation to determine whether women with vasomotor symptoms (VMS) — which include hot flashes and night sweats — had lower bone mineral density.

The researchers found that postmenopausal women with VMS had lower lumbar and total hip bone mineral density than those without VMS. Premenopausal women and early perimenopausal women who had VMS were found to have lower femoral neck bone mineral density than those without VMS.

AUTHORS: UCLA study co-authors Dr. Carolyn J. Crandall, associate clinical professor of general internal medicine and health services research; Gail A. Greendale, professor of medicine in geriatrics; and Yan Zheng, of the division of general internal medicine and health services research, are available for interviews.

JOURNAL: The research appeared in the March/April 2009 issue of the journal Menopause.

FUNDING: The National Institute on Aging, the U.S. Department of Health and Human Services' National Institutes of Health, the National Institute of Nursing Research, and the NIH Office of Research on Women's Health supported this study.

Bone Density of Hip Connected to Breast Cancer Risk After Menopause

By Crystal Phend
TUSCON, Ariz., 29 july 2008 -- Strong bones in postmenopausal women may correlate with higher breast cancer risk, researchers said.
Each unit increase in total hip bone mineral density T-score was linked to a 25% greater risk of developing breast cancer, Zhao Chen, Ph.D., M.P.H., of the University of Arizona, and colleagues, reported in the Sept. 1 issue of CANCER.
Although the traditional Gail score was a stronger predictor -- with a 35% increased breast cancer risk for postmenopausal women with a high score -- bone mineral density modestly added to the predictive value in an analysis of the prospective Women's Health Initiative study.
The Gail risk model is a well known tool that estimates the 5-year and lifetime risk of invasive breast cancer for women 35 and older. The version of the Gail score most widely used currently includes race/ethnicity, a history of atypical hyperplasia, and a history of lobular carcinoma in situ.
Women with the highest scores on both assessments showed a sharp increase in incident breast cancer (P<0.05).
Rather than suggesting a benefit of low bone mineral density, which increases fracture risk, the study supported using clinical information from osteoporosis screening to aid breast cancer risk assessment or even as an alternative to the Gail model, the researchers said.
Other studies have also supported a link between breast cancer and bone mineral density, but this was the first to add evaluation of Gail risk assessment results in the same population of women.
The analysis included 9,941 women (average age 63) who had a dual-energy X-ray absorptiometry (DEXA) scan at one of three clinical centers in the larger Women's Health Initiative study.
During more than eight years of follow-up, 327 women developed breast cancer.
Both high bone mineral density and high Gail scores were associated with breast cancer rates.
Women with a high Gail score of at least 1.67 had an age-adjusted breast cancer incidence of 47.8 per 10,000 person-years whereas for women with lower Gail scores the incidence was 33.1 per 10,000 person-years.
Likewise, age-adjusted incidence rose with total hip bone mineral density T-score. Incidence was as follows:
For women with T-scores in the normal range, 45.5 breast cancer cases per 10,000 person-years.
For women with a low bone mineral density, 29.5 cases per 10,000 person-years.
For women with T-scores in the osteoporosis range, 11.0 cases per 10,000 person-years.
Including the Gail score and hip bone mineral density T-score together in the same model across the entire population, both assessments retained significance as independent predictors with little or no change in the hazard ratios for breast cancer risk (HR 1.47 for Gail score of 1.67 or higher, P=0.001, and HR 1.26 for higher bone density, P<0.001).
Women with both very high Gail scores and bone mineral density were found to be at an exceptionally high risk for breast cancer in the current study. However, the interaction between the Gail score and bone mineral density T-score is confined to the higher-risk groups on both measures.
Adding other major risk factors for breast cancer, including body mass index, race or ethnicity, hormone use, and smoking history, only slightly attenuated the associations (HR 1.35 for high Gail score, P=0.02, and HR 1.25 for higher bone density, P<0.001).
This suggested that confounding by known breast cancer risk factors did not account for the correlations, the researchers said. "However, considering these factors may enhance the prediction."
For the women overall and those with below-average Gail scores and total hip bone density, the two tests did not interact significantly. However, breast cancer risk increased sharply for women above the median on both scores with a significant interaction (P=0.002).
The results may have limited generalizability because of the relatively small number of minority women and the potentially more health-conscious population enrolled in the study, Dr. Chen and colleagues noted.
The study was funded by Eli Lilly.
One of the researchers reported acting as a consultant for Astra-Zeneca, Novartis, and Genentech and receiving grant support from Amgen.

Primary source: CancerSource reference:Chen Z, et al "Hip bone density predicts breast cancer risk independently of Gail score -- Results from the Women's Health Initiative" Cancer 2008; 113.