Prognostic Value of Exercise Testing in Patients with Liver Cirrhosis

Background/Objectives: Cirrhosis is associated with increased mortality. In this study, we aimed to investigate the prognostic relevance of 6-min-walk-distance- and cardiopulmonary exercise testing (CPET)-derived peak oxygen uptake (VO₂) as estimates of exercise capacity in outpatients with cirrhosis. Methods: Patients underwent a comprehensive clinical characterization including cardiopulmonary exercise testing, six-minute-walking-test-derived distance, and echocardiography. We stratified the cohort using established prognostic thresholds for the six-minute-walking-test-derived distance (440 m) and peak VO₂ (65% predicted) and Child-Pugh class (A vs. B/C). Competing risk analyses were performed using cumulative incidence functions and subdistribution hazard models to assess the impact of baseline variables on mortality, accounting for liver transplantation (LT) as a competing event and for age and sex. The prognostic value of exercise performance was analyzed first, followed by the stepwise inclusion of additional variables; multicollinearity precluded a full multivariable model. Results: We enrolled 197 patients in Child-Pugh Class A, B, and C (N = 92, N = 80, N = 25 patients; male N = 146, age: 56 ± 9 years). During the observation time of 85 (25-105) months, 48 patients underwent a liver transplant, and 88 died. Both the six-minute-walking-test-derived distance ≤ 440 m (p = 0.002, sHR: 0.996 95% CI: 0.993-0.998) and peak VO₂ ≤ 65% predicted (p = 0.023, sHR: 0.987 95% CI: 0.976-0.998) were strong independent predictors of mortality. While the six-minute-walking-test-derived distance consistently remained significant across most models, the peak VO₂ retained significance only when adjusted for creatinine. Combining exercise capacity and the Child-Pugh classification identified patients at a particularly high mortality risk. Conclusions: In patients with liver cirrhosis outside the liver transplant setting, the impaired six-minute-walking-test-derived distance and peak VO₂ serve as predictors of mortality and may help to identify patients at a particularly high mortality risk. These results suggest that functional capacity provides complementary information to established liver disease severity scores and could be considered in a multidimensional risk assessment approach in patients with liver cirrhosis.