Women with both sarcopenia and low bone density appear to have a higher risk of fracture, particularly at the hip, than healthy women without either condition. Research is needed to gain a better understanding of the mechanisms at work.
Osteoporotic fractures can increase risks of morbidity and mortality, and these fractures occur disproportionately in older adults, partly because of age-associated declines in bone mineral density (BMD). Loss of strength and physical performance and sarcopenia―which has been defined as the loss of muscle mass―have also been associated with fractures. Despite knowledge of these links, few studies have explored the associations between sarcopenia, BMD, and fracture risk in women.
For a study published in the Journal of the American Geriatrics Society, Rebekah Harris, PT, DPT, and colleagues used data from the Women’s Health Initiative (WHI) to determine if women with sarcopenia and low BMD were at greater risk of fractures than those with sarcopenia or low BMD alone “The WHI study involved more than 161,000 women from 40 clinical centers across the United States,” explains Dr. Harris. “It also has over 15 years of follow-up on fractures and a comprehensive assessment of their participants over that time period. This data enabled us to do a thorough investigation into how sarcopenia and low BMD play a role in fracture risk.”
The study classified participants into mutually exclusive groups based on BMD and sarcopenia status. Women with low BMD, with or without sarcopenia, had greater risk of fracture than healthy women without either condition overall (Table). “Our findings indicate that low BMD, as measured by DXA scans, continues to be a strong risk factor for fracture among women,” Dr. Harris says. “In addition, the combination of low BMD and sarcopenia suggested a risk of hip fracture among women that was 278 times higher than those without low BMD and sarcopenia. Women with low BMD alone had a risk that was 242 times greater than those without sarcopenia and low BMD. We believe these associations are robust because we accounted for known potential confounders.”
The observations regarding the increase in hip fracture risk were interesting, according to Dr. Harris, because this association is different from what has been previously reported among men. “It’s possible that other factors are in play,” she says. “These factors may include muscle quality, hormonal differences, and different rates of lean mass that was lost.”
Implications & Future Research
Considering the study results, Dr. Harris says clinicians should continue using current screening methods for women at high risk of fracture. “It’s important to assess the hallmarks of fracture risk, including family history, fall history, bone density, and physical function level,” she says. “The next step is to gain a better understanding of how we can best capture sarcopenia. For instance, we often think of sarcopenia being connected only to small frail adults, but the condition is also present in obese people. More information is needed on how changes in muscle quality impact physical function among women.”
The field of sarcopenia continues to change and there are currently multiple definitions of the term that are consistently used in published research. “These varying definitions have different cut point values for lean mass and function, which creates challenges when trying to incorporate findings into practice,” explains Dr. Harris. She adds that imaging should also be utilized because it provides more detail about the muscle tissue itself rather than using broad assessments based on quantity alone.
Dr. Harris notes that her study team’s research, in addition to investigations being conducted by others in the field, can be used to develop a better understanding of how to intervene to prevent fractures in the future. “We know that low BMD is still a strong predictor of fracture, and the addition of sarcopenia further increases risk,” she says. “Now, we need more insights into the mechanisms at work in these processes.”
Harris R, Chang Y, Beavers K, et al. Risk of fracture in women with sarcopenia, low bone mass, or both. J Am Geriatr Soc. 2017;65:2673-2678. Available at: https://www.ncbi.nlm.nih.gov/pubmed/28960230 or https://www.medscape.com/viewarticle/890131_print.
Chalhoub D, Cawthon PM, Ensrud KE et al. Risk of nonspine fractures in older adults with sarcopenia, low bone mass, or both. J Am Geriatr Soc .2015;63:1733-1740.
Cawthon PM, Blackwell TL, Cauley J et al. Evaluation of the usefulness of consensus definitions of sarcopenia in older men: results from the Observational Osteoporotic Fractures in Men Cohort Study. J Am Geriatr Soc. 2015;63:2247-2259.