Possible Use of Body Surface Area Value for Estimating Skeletal Muscle Mass in Chronic Liver Disease

Background/Objectives: Sarcopenia is an important clinical feature of patients with chronic liver disease (CLD). However, special devices are required to determine skeletal muscle mass. We evaluated the usefulness of body surface area (BSA) for estimating muscle mass and diagnosing sarcopenia in patients with CLD. Methods: We retrospectively studied 1889 Japanese patients with CLD who underwent bioimpedance analysis (BIA) (training cohort, n = 983; validation cohort, n = 906). The optimal cutoff values for predicting low skeletal muscle mass index (SMI) were determined using ROC analysis. We also assessed 1229 patients whose BSA and grip strength (GS) data were obtained on the same day and evaluated the diagnostic performance of the determined cutoff values of BSA for the diagnosis of sarcopenia. Results: In the training cohort, a strong correlation was observed between the SMI and BSA (r = 0.883, p < 0.0001). The cutoff values of BSA for predicting low SMI were 1.68 m² for men and 1.48 m² for women. Regarding the presence of low SMI, 776 (78.9%) and 730 (80.5%) patients were correctly diagnosed in the training and validation cohorts, respectively. The sensitivity and specificity of the combination of BSA and GS for sarcopenia were 82.7% and 97.1%, respectively, and 1175 patients (95.6%) were correctly diagnosed. Conclusions: BSA was highly correlated with SMI, suggesting that BSA could facilitate noninvasive estimation of low skeletal muscle mass in patients with CLD.