Validation of cutoffs for skeletal muscle mass index based on computed tomography analysis against dual energy X-ray absorptiometry in patients with cirrhosis: the KIRRHOS study

Background Accurate assessments of muscle mass in patients with cirrhosis are necessary in clinical practice. Computed tomography (CT) of the upper abdomen has been proposed as a useful method for quantifying muscle mass. Recently, Carey et al developed specific cutoffs for muscle wasting based on the skeletal muscle index at the L3 vertebra (L3-SMI) for cirrhotic patients. The aim of the present study was to assess the concurrent validity of the newly proposed cutoffs of Carey et al, along with others widely used in several clinical contexts, using dual energy X-ray absorptiometry (DXA) as the reference method. Methods Data were evaluated from 97 Caucasian patients (59.8% male, 59.1 +/- 11.6 years old, 45.4% decompensated) with cirrhosis of various etiologies. Muscle mass was assessed using the appendicular lean mass index (ALMI) by DXA and the L3-SMI by CT. Low L3-SMI was defined in relation to 5 different cutoffs. Results Low muscle mass prevalence was 13.4% according to ALMI and 26.8-45.4% according to the different cutoffs applied for L3-SMI. The Carey et al, Prado et al and Montano-Loza et al cutoffs showed similar sensitivity (all 69.2%) and specificity (79.8%, 76.2% and 75.0%, respectively) and high accuracy (78.4%, 75.3% and 74.2%). The Carey et al cutoffs showed the highest diagnostic validity against DXA: the multivariate odds ratio adjusted for age, sex, body mass index category, disease etiology and model for end-stage liver disease score (95% confidence interval) was 5.88 (1.36-25.4), P=0.018. Conclusion Compared to DXA, the cutoffs for identifying muscle wasting proposed by Carey et al were proven to be the most accurate.