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Loss of muscle strength tied to mortality risk after fracture
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In older adults, reduced muscle strength increases the risk for mortality after a fracture, according to findings published in the Journal of Bone and Mineral Research.
“Patients with a fracture are at increased risk of premature mortality — more so in men than in women — but it is not clear which factors are responsible for this risk,” Tuan V. Nguyen, PhD, of the Garvan Institute of Medical Research in Australia, told Endocrine Today.
Nguyen and colleagues evaluated data from the Dubbo Osteoporosis Epidemiology Study (DOES) on 889 women (mean age at baseline, 72 years) and 295 men (mean age, 73 years) with a least one low-trauma fracture after age 50 years (mean age at fracture, 75 years for both men and women) to determine the relationships between muscle strength and mortality after fracture. Median follow-up was 11 years.
Changes in muscle strength before and after fracture were examined in a subset of 344 women and 99 men who had at least two muscle strength measurements before and after fracture and in another subset of 407 women and 105 men with at least two measurements after the fracture.
Through follow-up, 41.2% of women and 50.9% of men died.
Muscle strength at age 70 years was lower in women (14.6 kg/m) compared with men (22.3 kg/m); no significant differences in strength or rate of loss of strength were found before compared with after fracture for men or women.
The mortality risk after fracture increased by 19% in women and 39% in men for each standard deviation lower muscle strength after adjustment for age, femoral neck bone mineral density, BMI, physical activity, smoking, history of falls and illnesses.
Muscle weakness in women accounted for fewer premature deaths after fractures (15%) compared with men (23%).
“In this study, we found that the age-related decline in muscle strength was associated with ~30% increase in the risk of death following an osteoporotic fracture,” Nguyen told Endocrine Today. “I would also like to emphasize that in young adults lean muscle mass made up about 50% of body weight, but this composition reduces to about 25% to 30% in older people. Therefore, muscle mass and muscle strength are keys to healthy aging. There are two clinical messages from our study. First, primary care physicians should be aware that patients with any osteoporotic fracture, not just a hip fracture, are at increased risk of death, and they should be assessed and treated accordingly. Second, the assessment of post-fracture mortality risk should include — among others — muscle strength and muscle loss.” – by Amber Cox
For more information:
Tuan V. Nguyen, PhD, can be reached at Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst NSW 2010, Australia.
Disclosure: Nguyen reports various financial ties with BUPA, Merck Sharp & Dohme, Novartis, Roche, Servier and Sanofi-Aventis.
Perspective
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Ray Marks
Osteoporotic fractures, which commonly lead to disabling osteoarthritis, premature death or reduced life quality, remain an important costly health concern facing aging populations. This study focuses on the role of knee muscle weakness, a factor reported to increase the risk for falling and fracturing a hip or another bone, plus its ensuing disability. The authors verified that despite some design limitations, lower leg muscle weakness, specifically knee extensor muscle weakness, may partially predict mortality post-fracture. Moreover, this effect may be influenced by sex. That is, those with weaker muscles had a higher risk of mortality; those who were older and those who were men showed higher absolute strength losses compared with women. These data seem consistent with the associated findings of others, but were novel in the context of examining different types of fragility fractures.
Despite some study limitations, the study provides support for more research as well as careful comprehensive screening, diagnostic and preventive efforts focused on muscle. The research also supports a need to intervene to improve or maximize knee muscle extensor strength in the older population as well as in the context of rehabilitation strategies for restoring functional recovery after fracture surgery, particularly in the context of fragility fractures. Clinicians working with older adults can use these data in the realm of assessment, treatment and clinical education to promote the well-being of adults over age 50 years who are at risk for osteoporosis.
Disclosure: Marks reports no relevant financial disclosures.
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