Cutpoints for low appendicular lean mass that identify older adults with clinically significant weakness

Area of Science:

• Gerontology
• Human Physiology
• Biostatistics

Background:

• Low lean mass is a significant concern in older adults, but validated diagnostic criteria are lacking.
• The Foundation for the National Institutes of Health (FNIH) Sarcopenia Project aimed to establish empirical criteria for low lean mass.
• Weakness in older adults is defined by grip strength thresholds: <26kg for men and <16kg for women.

Purpose of the Study:

• To identify validated cutpoints for appendicular lean body mass (ALM) that indicate low lean mass in older adults.
• To determine thresholds of ALM that discriminate the presence or absence of weakness.
• To provide empirically validated criteria for assessing lean mass in geriatric populations.

Main Methods:

• Pooled cross-sectional data from 7,582 men and 3,688 women were analyzed.
• Classification and Regression Tree (CART) analysis was employed to derive ALM cutpoints.
• Mixed-effects logistic regression quantified the association between lean mass categories and weakness.

Main Results:

• CART analysis identified primary ALM cutpoints for low lean mass: <19.75kg in men and <15.02kg in women.
• Secondary definitions using ALM indexed by BMI (ALMBMI) were <0.789 for men and <0.512 for women.
• Low lean mass was significantly associated with weakness in both men and women across primary and secondary definitions.

Conclusions:

• Empirically derived ALM cutpoints effectively identify older adults with a higher likelihood of weakness.
• These validated thresholds provide a tool for clinical assessment of sarcopenia and related conditions.
• The findings contribute to a better understanding of lean mass's role in geriatric health and functional decline.