The value of different CT‐based methods for diagnosing low muscle mass and predicting mortality in patients with cirrhosis

BACKGROUND & AIMS: Low muscle mass impacts on morbidity and mortality in cirrhosis. The skeletal‐muscle index (SMI) is a well‐validated tool to diagnose muscle wasting, but requires specialized radiologic software and expertise. Thus, we compared different Computed tomography (CT)‐based evaluation methods for muscle wasting and their prognostic value in cirrhosis. METHODS: Consecutive cirrhotic patients included in a prospective registry undergoing abdominal CT scans were analysed. SMI, transversal psoas muscle thickness (TPMT), total psoas volume (TPV) and paraspinal muscle index (PSMI) were measured. Sarcopenia was defined using SMI as a reference method by applying sex‐specific cut‐offs (males: <52.4 cm(2)/m(2); females: <38.5 cm(2)/m(2)). RESULTS: One hundred and nine patients (71.6% male) of age 57 ± 11 years, MELD 16 (8‐26) and alcoholic liver disease (63.3%) as the main aetiology were included. According to established SMI cut‐offs, low muscle mass was present in 69 patients (63.3%) who also presented with higher MELD (17 vs 14 points; P = .025). The following optimal sex‐specific cut‐offs (men/women) for diagnosing low muscle mass were determined: TPMT: <10.7/ <7.8 mm/m, TPV: <194.9/ <99.2 cm(3) and PSMI <26.3/ <20.8 cm(2)/m(2). Thirty (27.5%) patients died during a follow‐up of 15 (0.3‐45.7) months. Univariate competing risks analyses showed a significant risk for mortality according to SMI (aSHR:2.52, 95% CI: 1.03‐6.21, P = .043), TPMT (aSHR: 3.87, 95% CI: 1.4‐8.09, P = .007) and PSMI (aSHR: 2.7, 95% CI: 1.17‐6.23, P = .02), but not TPV (P = .18) derived low muscle mass cut‐offs. In multivariate analysis only TPMT (aSHR: 2.82, 95% CI: 1.20‐6.67, P = .018) was associated with mortality, SMI (aSHR: 1.93, 95% CI: 0.72‐5.16, P = .19) and PSMI (aSHR: 1.93, 95% CI: 0.79‐4.75, P = .15) were not. CONCLUSION: Low muscle mass was highly prevalent in our cohort of patients with cirrhosis. Gender‐specific TPMT, SMI and PSMI cut‐offs for low muscle mass can help identify patients with an increased risk for mortality. Importantly, only TPMT emerged as an independent risk factor for mortality in patients with cirrhosis.