Loss of muscle strength tied to mortality risk after fracture
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
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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.