Muscle strength, performance metrics may improve fracture risk prediction for older men
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Muscle strength and physical performance measures may improve fracture risk prediction for older men and should be incorporated into fracture prediction models, according to study findings.
In analysis of data from the Osteoporotic Fractures in Men study, the addition of grip strength and chair stand improved predictions for any fracture, and gait speed improved predictions for hip fractures beyond the performance of the Garvan fracture risk calculator and the Fracture Risk Assessment Tool (FRAX) algorithms.
“We found surprisingly that these measures of muscle were as, or more important, than other commonly recognized fracture risk factors such as prior fracture, falls, smoking, alcohol and glucocorticoid use,” Dima Alajlouni, MSCMed, a PhD student in the bone biology division at Garvan Institute of Medical Research in Australia, told Healio. “Apart from age and femoral neck bone mineral density — the two most important risk factors for fracture — muscle strength and performance were ranked equal to or better than all the other established risk factors included in FRAX and Garvan fracture risk assessment tools.”
Alajlouni and colleagues collected data from 5,665 men aged 65 years or older from six communities in the U.S. with data available on muscle strength and performance as well as risk factors included in the Garvan and FRAX algorithms. Clinical data and demographics were collected at baseline. BMD was assessed with a DXA scan at the femoral neck. Grip strength was measured using a dynamometer, gait speed was assessed with a 6-m walking test, and chair stand was measured by calculating the time required to do five repeated extended stands from a full sitting position on an armless chair. Fractures were self-reported every 4 months, with a follow-up telephone interview conducted to collect information about the reported fracture. Net reclassification improvement was calculated to measure the predictive utility of the muscle strength and physical performance tests.
The findings were published in the Journal of Bone and Mineral Research.
During a median follow-up of 12.7 years, about 18% of the study cohort sustained at least one fracture. Men who had a fracture had lower grip strength and a longer chair stand times than those without a fracture. Gait speed was lower in those who had a major osteoporotic fracture or hip fracture, but not any fracture.
In the Garvan and FRAX risk prediction models for any fracture and major osteoporotic fracture, grip strength and chair stand were equal to or more important than all variables except for age and femoral neck BMD. All three performance metrics were equal to or more important than all variables except for age and BMD for hip fracture prediction models.
Grip strength, chair stands improve any fracture prediction
The addition of grip strength (net reclassification improvement, 3.9%; 95% CI, 2.3-6.1) and chair stands (net reclassification improvement, 3.2%; 95% CI, 0.1-6.1) improved the prediction of any fracture. Adding both grip strength and chair stands to the algorithms resulted in an even greater prediction improvement (net reclassification improvement, 5.7%; 95% CI, 2.3-9.2). Gait speed did not improve the prediction of any fracture. Grip strength (net reclassification improvement, 5.2%; 95% CI, 1.7-9.6) and chair stands (net reclassification improvement, 6.1%; 95% CI, 0.3-11.5) also improved the prediction of major osteoporotic fractures, with a larger improvement observed with both metrics combined (net reclassification improvement, 8.9%; 95% CI, 3.7-13.8).
Gait speed improves initial and any hip fracture prediction
For initial hip fractures, gait speed was the only individual metric to improve risk prediction (net reclassification improvement, 5.7%; 95% CI, 0.5-12.3). Combining grip strength and gait speed also improved initial hip fracture prediction (net reclassification improvement, 9.4%; 95% CI, 6-14.2). Results for any hip fracture followed the same pattern.
“There are simple measures of muscle function that can easily be performed in the clinic that may enhance the identification of older men at high risk for fracture,” Alajlouni said. “Therefore, a measure of muscle strength and/or performance should be considered for inclusion in fracture risk assessment tools.”
Alajlouni added that larger studies are needed to confirm the findings in a different cohort of men as well as in women. The findings could also lead to the development of a new fracture prediction tool incorporating muscle strength and performance metrics.
For more information:
Dima Alajlouni, MScMed, can be reached at d.alajlouni@garvan.org.au.
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