Validity of anthropometric equations for the estimation of muscle mass in the elderly Validade de equações antropométricas para estimar a massa muscular em idosos

The objective of this study was to compare skeletal muscle mass (SMM) in older adults as estimated by dual-energy X-ray absorptiometry (DXA) and three predictive equations. A total of 180 older adults (120 women and 60 men) aged 60 to 81 years were studied. Appendicular SMM was measured by DXA and estimated using predictive equations based on anthropometric measures, age, race, and gender. Agreement between methods was evaluated by the paired t-test, Pearson’s correlation coefficient, and dispersion error. The prevalence of sarcopenia estimated with the different methods was compared using the kappa coefficient, sensitivity, and specificity. No difference was observed in mean SMM estimated by the predictive equation of Lee et al. and DXA (p>0.05), with a high correlation between methods in men (r=0.90; p<0.001) and women (r=0.86; p<0.001). The prevalence of sarcopenia did not differ between methods (DXA = 33.3% vs. equation = 36.1%), with high agreement between methods (kappa = 0.74; p<0.001) and high specificity (89%) and sensitivity (86%). The results indicate agreement between DXA and the predictive equation of Lee et al. for estimation of SMM and prevalence of sarcopenia in older adults.