Summary The relationship between a new measure of total skeletal muscle mass (assessed by D3-creatine [D3Cr] dilution) and incident fracture is unknown. In 1363 men (mean age 84.2 years), we determined D3Cr muscle mass; Fracture Risk Assessment Tool (FRAX) 10-year probability of major hip and osteoporotic fracture (hip, humerus, vertebra, forearm); and femoral neck bone mineral density (BMD) (using dual-energy x-ray absorptiometry [DXA]). Incident fractures were adjudicated centrally by review of radiology reports over 4.6 years. Height and weight-adjusted correlations between femoral neck BMD and D3Cr muscle mass were calculated. Across D3Cr muscle mass/weight quartiles, proportional hazards models estimated hazard ratios (HRs) for either (n = 180); non-spinal (n = 153); major osteoporotic fracture (n = 85); and hip fracture (n = 40) after adjustment for age, femoral neck BMD, history of recurrent falls, and likelihood of FRAX. The models were then fitted to assess the mediating influence of physical performance (walking speed, chair standing, and grip strength). D3Cr muscle mass was weakly correlated with femoral BMD (r = 0.10, p < 0.001). Compared with men in the highest quartile, those in the lowest quartile of muscle mass/D3Cr weight had an increased risk of any clinical fracture (HR, 1.8; 95% confidence interval [CI], 1.1). –2.8); nonvertebral fracture (HR 1.8; 95% CI, 1.1–3.0), major osteoporotic fracture (HR 2.3; 95% CI, 1.2–4.6), and hip fracture (HR 5 .9; 95% CI, 1.6–21.1). Results were attenuated after adjustment for physical performance, but associations remained borderline significant for hip and major osteoporotic fractures (p ≥ 0.05 to 0.10). Low D3Cr muscle mass/weight is associated with a markedly high risk of hip fracture and potentially other fractures in older men; this association is partially mediated by physical performance. |
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Older men with lower amounts of muscle mass have a significantly higher risk of hip and potentially other fractures, new research led by researchers at Sutter Health’s San Francisco Coordinating Center (SFCC) in San Francisco has shown. Francisco, CA.
The results of a prospective study were published online earlier this month in the Journal of Bone and Mineral Research , the official publication of the American Society for Bone and Mineral Research.
“Previous findings from our research and other studies have shown that low DXA lean mass, a commonly used but inaccurate approximation of muscle, is not related to increased fracture risk. This has led some researchers to erroneously conclude that muscle is relatively unimportant for fracture risk,” says Peggy Cawthon, Ph.D., lead author of the study, principal investigator of the Men’s Osteoporotic Fracture Study Research Group. (MrOS) at SFCC and professor in the department of epidemiology and biostatistics at the University of California, San Francisco. "However, these new results suggest that low muscle mass is indeed associated with an increased risk of hip fractures in older men, even after accounting for factors such as age and bone mineral density that may influence mass." muscle and the risk of fractures.
Dr. Cawthon and colleagues at leading U.S. academic medical centers prospectively studied 1,363 men (mean age, 84.2 years). Fracture risk was determined by D3Cr muscle mass quartile, and the study authors also investigated the mediating influence of physical performance (walking speed, chair standing, and grip strength) on the relationship between muscle mass and fracture. .
The results showed that D3Cr muscle mass was weakly correlated with femoral BMD (r=0.10, p<0.001). However, D3Cr muscle mass was strongly correlated with fractures, especially hip fracture. Compared with men in the highest quartile, those in the lowest quartile of D3Cr muscle mass/weight were approximately twice as likely to have a clinical fracture, any fracture other than the spine, and had approximately six times as likely to have odds of having a hip fracture after approximately four years of follow-up. The study authors believe that the relationship between D3CR muscle mass and fracture may be mediated by poor physical performance.
The D3Cr dilution assessment of muscle mass, currently available only in research settings and being tested by the MrOS study and other investigators for clinical use, relies on several aspects of creatine biology to estimate muscle mass. They are not based on the same assumptions as compartmental models (such as DXA), and therefore may represent a more accurate assessment of muscle mass.
“ The clear association between muscle mass and hip fracture was surprising . ” For example, men in the lowest quartile of muscle mass were almost six times more likely to suffer a fracture than men in the highest quartile,” says Steve Cummings, MD, director of SFCC and principal investigator of MrOS at Sutter’s California. Pacific Medical Center.
“Our findings suggest that muscle mass is an important contributor to fractures. Strength exercise and even simple activities such as climbing stairs may be important for maintaining muscle strength and preventing fractures, however, more information from the best evidence (randomized controlled trials) is needed to confirm these findings and help guide decision making. clinical decisions.
Dr. Cawthon notes that a limitation of the study is that its only cohort was male, as the muscle mass measure was added to an ongoing study of osteoporosis in men (MrOS). “It is important to determine whether these associations are also true in women,” she says. "If so, it will be critical to test whether interventions that improve muscle mass also reduce fracture risk, and how assessment of D3Cr dilution from muscle mass can potentially be used in the clinic to measure health outcomes."
About 36 million falls are reported among older adults each year, resulting in more than 32,000 deaths. Each year, about three million older adults are treated in emergency departments for a fall injury. One in five falls results in an injury, such as broken bones or head injuries. Every year, at least 300,000 older people are hospitalized for hip fractures.
This study was supported by the National Institutes of Health, with funding from the National Institute on Aging, the National Institute of Arthritis and Musculoskeletal and Skin Diseases, and the National Center for Advancing Translational Sciences.
