BOSTON – An index that takes into account the ratio between body mass index (BMI) and bone mineral density (BMD) correlated well with trabecular bone scores, a newer assessment of bone fragility. The index may help predict risk for fragility fractures in individuals with obesity when trabecular bone scores are not available.
“Obesity is traditionally thought to be protective against bone fractures,” said Mikiko Watanabe, MD, an endocrinologist at Sapienza University of Rome. “But recent evidence suggests that this is not entirely true, especially in morbidly obese patients.”
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Lumbar spine BMD alone may not accurately capture bone fragility in patients with obesity, said Dr. Watanabe in an interview at the annual meeting of the American Association of Clinical Endocrinologists.
Adding the trabecular bone score (TBS) to BMD gives additional information about bone microarchitecture, refining risk assessment for fragility fractures. This newer technology, however, may not be readily available and may be associated with extra cost.
Accordingly, said Dr. Watanabe, the study’s senior investigator, Sapienza University’s Carla Lubrano, MD, had the idea to index bone density to BMI, and then see how well the ratio correlated to TBS; obesity is known to be associated with lower TBS scores, indicating increased bone fragility.
Living in Italy, with relatively fewer medical resources available, “We were trying to find some readily available index that could predict the risk of fracture as well as the indexes that are around right now,” said Dr. Watanabe.
“We did find some very interesting data in our population of over 2,000 obese patients living in Rome,” she said. “We do confirm something from the literature, where BMD tends to go high with increasing BMI.” Further, the relatively weak correlation between TBS and BMI was confirmed in the investigators’ work (r = 0.3).