Sarcopenia, sarcopenic obesity and mortality in older adults: results from the National Health and Nutrition Examination Survey III

Sarcopenia is defined as the loss of skeletal muscle mass and quality, which accelerates with aging and is associated with functional decline. Rising obesity prevalence has led to a high-risk group with both disorders. We assessed mortality risk associated with sarcopenia and sarcopenic obesity in elders. A subsample of 4652 subjects ⩾60 years of age was identified from the National Health and Nutrition Examination Survey III (1988–1994), a cross-sectional survey of non-institutionalized adults. National Death Index data were linked to this data set. Sarcopenia was defined using a bioelectrical impedance formula validated using magnetic resonance imaging-measured skeletal mass by Janssen et al. Cutoffs for total skeletal muscle mass adjusted for height2 were sex-specific (men: ⩽5.75 kg/m2; females ⩽10.75 kg/m2). Obesity was based on % body fat (males: ⩾27%, females: ⩾38%). Modeling assessed mortality adjusting for age, sex, ethnicity (model 1), comorbidities (hypertension, diabetes, congestive heart failure, osteoporosis, cancer, coronary artery disease and arthritis), smoking, physical activity, self-reported health (model 2) and mobility limitations (model 3). Mean age was 70.6±0.2 years and 57.2% were female. Median follow-up was 14.3 years (interquartile range: 12.5–16.1). Overall prevalence of sarcopenia was 35.4% in women and 75.5% in men, which increased with age. Prevalence of obesity was 60.8% in women and 54.4% in men. Sarcopenic obesity prevalence was 18.1% in women and 42.9% in men. There were 2782 (61.7%) deaths, of which 39.0% were cardiovascular. Women with sarcopenia and sarcopenic obesity had a higher mortality risk than those without sarcopenia or obesity after adjustment (model 2, hazard ratio (HR): 1.35 (1.05–1.74) and 1.29 (1.03–1.60)). After adjusting for mobility limitations (model 3), sarcopenia alone (HR: 1.32 ((1.04–1.69) but not sarcopenia with obesity (HR: 1.25 (0.99–1.58)) was associated with mortality. For men, the risk of death with sarcopenia and sarcopenic obesity was nonsignificant in both model-2 (HR: 0.98 (0.77–1.25), and HR: 0.99 (0.79–1.23)) and model 3 (HR: 0.98 (0.77–1.24) and HR: 0.98 (0.79–1.22)). Older women with sarcopenia have an increased all-cause mortality risk independent of obesity.