Concordance between measured and estimated appendicular muscle mass in adult females.

This study assessed the accuracy of a selected formula used to estimate the appendicular muscle mass (AMM) which is linked with many clinical outcomes. A group of community-dwelling adult women (n=80) had their AMM measured using dual energy x-ray absorptiometry (DXA). The same was estimated using a formula already published {Skeletal muscle mass = (0.244 × BW in kg) + (7.80 × Ht in meters) + (6.6 × Sex) - (0.098 × Age) + race - 3.3} (sex=0 for female and 1 for male, race =-1.2 for Asian, 1.4 for African American and 0 for White and Hispanic).The two datasets were compared for accuracy and precision. Mean AMM measured by DXA and estimated by the formula were very close (14.8 and 14.5 kg) and the difference ranged from -1.2 to 3.6 kg. Correlation between the two datasets was high (r=0.92) and the Bland-Altman plot showed an acceptable measurement agreement between the two methods. Results were independent of age and BMI. The formula used in this analysis gave an accurate estimation of the absolute AMM in women included in this study.