Low Lean Mass With and Without Obesity, and Mortality: Results From the 1999-2004 National Health and Nutrition Examination Survey

Background: The Foundation for the NIH Sarcopenia Project validated cutpoints for appendicular lean mass. We ascertained the relationship between low lean mass (LLM), obesity, and mortality and identified predictors in this subgroup.

Methods: A total of 4,984 subjects aged 60 years and older were identified from the National Health and Nutrition Examination Survey 1999-2004 linked to the National Death Index. LLM was defined using reduced appendicular lean mass (men < 19.75 kg; females < 15.02 kg). Obesity was defined using dual-energy x-ray absorptiometry body fat (males ≥ 25%; females ≥ 35%). LLM with obesity was defined using criteria for both LLM and obesity. Proportional hazard models determined mortality risk for LLM and LLM with obesity, separately (referent = no LLM and no LLM with obesity, respectively).

Results: Mean age was 71.1 ± 0.19 years (56.5% female). Median follow-up was 102 months (interquartile range: 78, 124) with 1,901 deaths (35.0%). Prevalence of LLM with obesity was 33.5% in females and 12.6% in males. In those with LLM, overall mortality risk was 1.49 (1.27, 1.73) in males and 1.19 (1.02, 1.40) in females. Mortality risk in LLM with obesity was 1.31 (1.11, 1.55) and 0.99 (0.85, 1.16) in males and females, respectively. Age, diabetes, history of stroke, congestive heart failure, cancer, and kidney disease were predictive of death.

Conclusions: Risk of death is higher in subjects with LLM than with LLM and obesity. Having advanced age, diabetes, stroke, heart failure, cancer, and renal disease predict a worse prognosis in both classifications.