Prognostic value of muscle mass assessed by DEXA in elderly hospitalized patients

To analyze the prognostic value of lean mass measured by DEXA and to compare it with lean muscle mass assessed by anthropometrics, calf circumference, subjective assessment and with physical muscle function tests in elderly hospitalized patients.

We study 187 hospitalized patients aged ≥65 years. We assessed nutrition by anthropometrics, mid arm muscle area, triceps skinfold and calf circumference, by subjective nutritional assessment and by DEXA, lean and fat mass and bone mineral density (BMD); muscle function by handgrip strength, gait speed, standing balance and stand-up test; disability and activities of daily living and the clinical frailty score; and comorbidity by Charlson index. Outcomes were assessed by mortality at 100 days and long-term follow up.

Male sex showed higher comorbidity and mortality although females were older, with decreased muscle mass and function, disabled and frailer. Long term mortality was also related to decreased lean mass evaluated by subjective assessment, midarm anthropometry, calf circumference and DEXA (appendicular lean and fat mass and BMD); muscle function impairment assessed by gait speed, standing balance and stand-up test; frailty; disability and comorbidity. Variables with long term independent predictive value were comorbidity, inability to perform any of the muscle function tests: gait speed, standing balance and stand-up; subjective nutritional score, appendicular lean mass under the 10th percentile and male sex.

Females are older and frailer but with lower comorbidity; they showed a better survival. The best predictive mortality factor was comorbidity, but DEXA appendicular lean mass under the 10th percentile showed an independent and high predictive value on mortality.