Associations Of Sarcopenia And Low Muscular Strength With All-cause Mortality Among Us Older Adults

Abstract

Sarcopenia is defined as aging-related loss of muscle mass and knee extension strength serves as a marker of lower extremity muscular strength in populations. Sarcopenia and low muscular strength (LMS) may be important but understudied risk factors for aging-related morbidity and mortality in the older and elderly populations. PURPOSE: We aimed to prospectively examine individual or joint associations of sarcopenia and LMS with all-cause mortality in a nationally representative sample of US older adults in the National Health and Nutrition Examination Survey (NHANES). METHODS: Data sources included the NHANES 1999-2002 with public-use 2011 linked mortality files, which comprised 4,449 participants aged 50 years and older with complete data on body composition by dual-energy x-ray absorptiometry and isokinetic knee extensor strength measurement. Sarcopenia was defined by two definitions proposed by the National Institutes of Health Sarcopenia Project according to appendicular lean mass (ALM) and ALM divided by BMI (ALM/BMI). LMS was defined as the lowest 25% of measurements of knee extensor strength. Weighted multivariable logistic regression models were adjusted for age, sex, race, BMI, smoking, alcohol use, education, leisure time physical activity, sedentary time, and comorbidities. RESULTS: The weighted prevalence of sarcopenia was 23.1% defined by ALM and 17.0% defined by ALM/BMI; the weighted prevalence of low muscular strength was 19.4%. In the multivariate-adjusted models, sarcopenia was significantly associated with increased risk of all-cause mortality for ALM/BMI definition (OR: 1.44; 95% confidence interval [CI], 1.06-1.97) but not for ALM definition (OR: 1.37; 95% CI, 0.90-2.09) while LMS was strongly associated with all-cause mortality (OR: 2.32; 95% CI, 1.70-3.18). In the joint analyses, a significantly increased all-cause mortality was observed only among participants with LMS and non-sarcopenia (OR range: 2.03-2.50) and those with LMS and sarcopenia (OR range: 2.15-2.56) while those without sarcopenia and LMS were the reference group. CONCLUSIONS: Low knee extensor strength indicative of low muscular strength was independently and significantly associated with an increased risk of all-cause mortality among US older adults regardless of the presence or absence of sarcopenia.