Predictive equations for muscle mass in patients with spinocerebellar ataxia.

Objective: to compare anthropometric equations with one that uses BIA to predict muscle mass in patients with SCA. Methods: 76 patients with ages from 22 to 72 years had their muscle mass estimated by the equation that employs BIA and by five anthropometric equations. The results were analyzed using Pearson's and intraclass correlation coefficient, the paired t test and the Bland-Altman plot. Results: the mean weight and height ± SD were 64.2 ± 14 kg and 1.61 m ± 8 cm, respectively. The equation proposed by Lee et al. (2000), which uses body weight and height measurements, produced the best results in predicting muscle mass, since a significant bias value was not detected, and both a stronger linear correlation (r = 0.94) and higher intraclass correlation (ICC = 0.93). Conclusion: this anthropometric equation can be used to reliably estimate and monitor decreases in muscle mass in people with SCA.