Clinical usefulness of psoas muscle thickness for the diagnosis of sarcopenia in patients with liver cirrhosis

Abstract

Background/aims: The most widely used method for diagnosing sarcopenia is the skeletal muscle index (SMI). Several studies have suggested that psoas muscle thickness per height (PMTH) is also effective for detecting sarcopenia and predicting prognosis in patients with cirrhosis. The aim of this study was to evaluate the optimal cutoff values of PMTH for detecting sarcopenia in cirrhotic patients.

Methods: All cirrhotic patients who underwent abdominal computed tomography (CT) scan including L3 and umbilical levels for measuring SMI and transverse psoas muscle thickness, respectively, were included. Two definitions of sarcopenia were used: (1) sex-specific cutoffs of SMI (≤52.4 cm2 /m2 in men and ≤38.5 cm2 /m2 in women) for SMI-sarcopenia and (2) cutoff of PMTH (<16.8 mm/m) for PMTH-sarcopenia.

Results: Six hundred fifty-three patients were included. The average age was 53.6 ± 10.2 years, and 499 patients (76.4%) were men. PMTH correlated well with SMI in both men and women (P<0.001). Two hundred forty-one (36.9%) patients met the criteria for SMI-sarcopenia. The best PMTH cutoff values for predicting SMI-sarcopenia were 17.3 mm/m in men and 10.4 mm/m in women, and these were defined as sex-specific cutoffs of PMTH (SsPMTH). The previously published cutoff of PMTH was defined as sex-nonspecific cutoff of PMTH (SnPMTH). Two hundred thirty (35.2%) patients were diagnosed with SsPMTH-sarcopenia, and 280 (44.4%) patients were diagnosed with SnPMTH-sarcopenia. On a multivariate Cox regression analysis, SsPMTH-sarcopenia (hazard ratio [HR], 1.944; 95% confidence interval [CI], 1.144-3.304; P=0.014) was significantly associated with mortality, while SnPMTH-sarcopenia was not (HR, 1.446; 95% CI, 0.861-2.431; P=0.164).

Conclusion: PMTH was well correlated with SMI in cirrhotic patients. SsPMTH-sarcopenia was an independent predictor of mortality in these patients and more accurately predicted mortality compared to SnPMTH-sarcopenia.

Keywords: Cirrhosis; Prognosis; Psoas muscle; Sarcopenia.

Figure 1.

Measurement of psoas muscle thickness/height at the level of the umbilicus on a computed tomography (CT) scan image. Axial CT scan at the level of the umbilicus in a patient with hepatitis B virus-related cirrhosis and a model for end-stage liver disease (MELD) score of 10 with no ascites. Psoas muscle thickness corresponds to the diameter of transversal psoas muscle (left-right arrow) perpendicular to the axial diameter (dotted left-right arrow).

Figure 2.

Correlation between psoas muscle thickness/height and skeletal muscle index. Correlation between psoas muscle thickness/height and skeletal muscle index in all enrolled patients (A), in men (B), and in women (C). PMTH was well correlated with SMI (Pearson’s correlation coefficient, 0.526; P<0.001) (A). The Pearson’s correlation coefficient differed between men (0.505, P<0.001) (B) and women (0.380, P<0.001) (C). PMTH, psoas muscle thickness/height; SMI, skeletal muscle index.

Figure 3.

Area under the receiver operating characteristic curve for detecting sarcopenia. Area under the receiver operating characteristic curve for detecting sarcopenia defined by smooth muscle index based on psoas muscle thickness/height in men (A) and in women (B). The area under the receiver operating characteristic curve of psoas muscle thickness/height for predicting skeletal muscle index-sarcopenia was 0.779 (95% confidence interval [CI], 0.739-0.819) in men (A) and 0.842 (95% CI, 0.772-0.912) in women (B).

Figure 4.

Kaplan-Meier analysis for survival according to the presence of sarcopenia. Kaplan-Meier curve for cumulative survival of patients with liver cirrhosis according to the presence of sarcopenia defined by smooth muscle index (A), sex-nonspecific PMTH (B), and sex-specific PMTH (C). With the definition of sarcopenia based on SMI, survival rates at 1, 2, and 3 years were 97.7%, 93.3%, and 88.3%, respectively, in patients without sarcopenia, while they were 86.2%, 81.0%, and 78.8% in patients with sarcopenia (P<0.001) (A). With the definition of sarcopenia based on the sex-nonspecific cutoff of PMTH, the survival rates at 1, 2, and 3 years were 95.3%, 91.5%, and 88.4%, respectively, in patients without sarcopenia, while they were 91.4%, 85.6%, and 80.6% in patients with sarcopenia (P=0.024) (B). With the definition of sarcopenia by sex-specific cutoff of PMTH, survival rates at 1, 2, and 3 years were 96.2%, 92.4%, and 89.7%, respectively, in patients without sarcopenia, while they were 90.2%, 84.1%, and 78.5% in patients with sarcopenia (P=0.002) (C). Pts, patients; PMTH, psoas muscle thickness/height; SMI, skeletal muscle index.