Aron S Buchman1,2, Sue E Leurgans1,2, Tianhao Wang1,2, Michal Schnaider-Beeri3,4, Puja Agarwal5, Robert J Dawe1,6, Osvaldo Delbono7, David A Bennett1,2. 1. Rush Alzheimer's Disease Center, Rush University Medical Center, Chicago, IL, United States of America. 2. Department of Neurological Sciences, Rush University Medical Center, Chicago, IL, United States of America. 3. Icahn School of Medicine at Mount Sinai, New York, NY, United States of America. 4. Joseph Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel. 5. Department of Internal Medicine, Rush University Medical Center, Chicago, IL, United States of America. 6. Department of Diagnostic Radiology and Nuclear Medicine, Rush University Medical Center, Chicago, IL, United States of America. 7. Section of Gerontology, Wake Forest School of Medicine, Winston-Salem, NC, United States of America.
Abstract
BACKGROUND: This study tested the hypothesis that sarcopenia and its constituent components, reduced lean muscle mass and impaired motor function, are associated with reduced survival and increased risk of incident disabilities. METHODS: 1466 community-dwelling older adults underwent assessment of muscle mass with bioelectrical impedance analysis (BIA), grip strength, gait speed and other components of physical frailty and annual self-report assessments of disability. We used Cox proportional hazards models that controlled for age, sex, race, education and height to examine the associations of a continuous sarcopenia metric with the hazard of death and incident disabilities. RESULTS: Mean baseline age was about 80 years old and follow-up was 5.5 years. In a proportional hazards model controlling for age, sex, race, education and baseline sarcopenia, each 1-SD higher score on a continuous sarcopenia scale was associated with lower hazards of death (HR 0.70, 95%CI [0.62, 0.78]), incident IADL (HR 0.80,95%CI [0.70, 0.93]), incident ADL disability (HR 0.80 95%CI [71, 91]) and incident mobility disability (HR 0.81, 95%CI [0.70, 0.93]). Further analyses suggest that grip strength and gait speed rather than muscle mass drive the associations with all four adverse health outcomes. Similar findings were observed when controlling for additional measures used to assess physical frailty including BMI, fatigue and physical activity. CONCLUSIONS: Motor function is the primary driver of the associations of sarcopenia and physical frailty with diverse adverse health outcomes. Further work is needed to identify other facets of muscle structure and motor function which together can identify adults at risk for specific adverse health outcomes.
BACKGROUND: This study tested the hypothesis that sarcopenia and its constituent components, reduced lean muscle mass and impaired motor function, are associated with reduced survival and increased risk of incident disabilities. METHODS: 1466 community-dwelling older adults underwent assessment of muscle mass with bioelectrical impedance analysis (BIA), grip strength, gait speed and other components of physical frailty and annual self-report assessments of disability. We used Cox proportional hazards models that controlled for age, sex, race, education and height to examine the associations of a continuous sarcopenia metric with the hazard of death and incident disabilities. RESULTS: Mean baseline age was about 80 years old and follow-up was 5.5 years. In a proportional hazards model controlling for age, sex, race, education and baseline sarcopenia, each 1-SD higher score on a continuous sarcopenia scale was associated with lower hazards of death (HR 0.70, 95%CI [0.62, 0.78]), incident IADL (HR 0.80,95%CI [0.70, 0.93]), incident ADL disability (HR 0.80 95%CI [71, 91]) and incident mobility disability (HR 0.81, 95%CI [0.70, 0.93]). Further analyses suggest that grip strength and gait speed rather than muscle mass drive the associations with all four adverse health outcomes. Similar findings were observed when controlling for additional measures used to assess physical frailty including BMI, fatigue and physical activity. CONCLUSIONS: Motor function is the primary driver of the associations of sarcopenia and physical frailty with diverse adverse health outcomes. Further work is needed to identify other facets of muscle structure and motor function which together can identify adults at risk for specific adverse health outcomes.
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Authors: Aron S Buchman; Sue E Leurgans; Patricia A Boyle; Julie A Schneider; Steven E Arnold; David A Bennett Journal: BMC Med Date: 2011-04-20 Impact factor: 8.775
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