Use of Skeletal Muscle Index as a Predictor of Wait List Mortality in Patients with End‐Stage Liver Disease

BACKGROUND: Sarcopenia is reduced muscle volume and is accelerated in patients with liver disease. This lethal complication of cirrhosis is associated with wait list mortality, post-operative complications, and post-transplant death. Skeletal muscle index (SMI), muscle area normalized to height, has been used as a marker for sarcopenia-related mortality. The aim of this study is to validate a proposed definition of sarcopenia in predicting waitlist mortality. METHODS: We retrospectively evaluated adults (age≥18) with cirrhosis listed for first-time LT from 01/01/10-04/01/18 from our center. Demographic, laboratory, and outcome data were collected in conjunction with CT scans performed within 3 months of listing. Using imaging analysis software, the skeletal muscle index (SMI) was calculated. Survival analysis was performed to evaluate the association of the proposed sarcopenia definition of SMI < 50 cm2 /m2 for men or SMI < 39 cm2 /m2 for women with wait list mortality or delisting. RESULTS: 355 patients were assessed. Median SMI was 54.1 cm2 /m2 (range 25-87). 17.2% of patients (61/355) exhibited sarcopenia according to the proposed threshold. 24.5% (57/232) of men were sarcopenic compared with 3.3% (4/123) of women (p <0.001). Mean SMI was also higher for men (56.6 +/- standard deviation cm2 /m2 ) than for women (50.8 +/- standard deviation cm2 /m2 , p < 0.001). Median follow-up time among patients who did not die while on the wait list or delist due to worsening condition was 2.1 months (0-12 months). 30 events were observed; hazard ratio, 0.98; 95% CI (0.95, 1.02; p=0.41). There was no statistically significant difference in time on wait list between patients with and without sarcopenia (p=0.89) defined at the threshold. CONCLUSION: Utilizing the pre-specified definitions of sarcopenia based on SMI, there was no statistically significant difference in mortality and delisting from the transplant wait list between patients with and without sarcopenia in this population. Practice and region-specific patterns for pre-transplant selection and median MELD at transplant may affect SMI as a predictor of waitlist mortality.