Systematic review: pre- and post-operative prognostic value of cardiopulmonary exercise testing in liver transplant candidates.

BACKGROUND: Cardiopulmonary exercise testing (CPET) is the gold standard for the objective assessment of functional status. In many conditions, CPET outperforms the traditional variables in predicting mortality.

AIM: In patients with cirrhosis listed for liver transplantation, our primary aim was to determine the prognostic value of CPET for pre-and post-transplant mortality and, in particular, whether CPET remained predictive after adjustment for liver disease severity.

METHODS: A systematic literature review was conducted in databases Medline, Scopus, Embase and PubMed. Where possible, data were pooled for meta-analyses using a DerSimonian and Laird random effects model.

RESULTS: A total of seven studies were retrieved, including 1107 patients with a mean MELD of 14.2 (standard deviation 1.6) and peak baseline VO2 of 17.4 mL/kg/min. In all of the studies in which multivariable analysis was performed, CPET variables were independent predictors of pre-transplant mortality (three studies) and post-transplant mortality (four studies). In the three studies where we could aggregate post-transplant mortality data, post-transplant mortality was predicted by AT with a mean difference of 2.0 (95% confidence interval, CI: 0.42-3.59; Z = 2.48, P = 0.01) between survivors and nonsurvivors. The peak VO2 was not significant (0.77 95% CI: -1.36 to 2.90; Z = 0.71, P = 0.48).

CONCLUSIONS: Patient's listed for liver transplant have significant functional limitations, with a weighted mean VO2 below the threshold level required for independent living. Although heterogeneity in study designs with respect to timing, CPET variables, and cut-off values precluded the determination of CPET mortality thresholds, the studies support CPET as an objective and independent predictor of pre- and post-transplant mortality.