Functional cardiovascular reserve predicts survival pre-kidney and post-kidney transplantation

Abstract

Exercise intolerance is an important comorbidity in patients with CKD. Anaerobic threshold (AT) determines the upper limits of aerobic exercise and is a measure of cardiovascular reserve. This study investigated the prognostic capacity of AT on survival in patients with advanced CKD and the effect of kidney transplantation on survival in those with reduced cardiovascular reserve. Using cardiopulmonary exercise testing, cardiovascular reserve was evaluated in 240 patients who were waitlisted for kidney transplantation between 2008 and 2010, and patients were followed for ≤5 years. Survival time was the primary endpoint. Cumulative survival for the entire cohort was 72.6% (24 deaths), with cardiovascular events being the most common cause of death (54.2%). According to Kaplan-Meier estimates, patients with AT <40% of predicted peak VO2 had a significantly reduced 5-year cumulative overall survival rate compared with those with AT ≥40% (P<0.001). Regarding the cohort with AT <40%, patients who underwent kidney transplantation (6 deaths) had significantly better survival compared with nontransplanted patients (17 deaths) (hazard ratio, 4.48; 95% confidence interval, 1.78 to 11.38; P=0.002). Survival did not differ significantly among patients with AT ≥40%, with one death in the nontransplanted group and no deaths in the transplanted group. In summary, this is the first prospective study to demonstrate a significant association of AT, as the objective index of cardiovascular reserve, with survival in patients with advanced CKD. High-risk patients with reduced cardiovascular reserve had a better survival rate after receiving a kidney transplant.

Figures

Figure 1.

Kaplan–Meier survival curves using AT 2 as the cut-off point for all-cause mortality.

Figure 2.

Effect of kidney transplantation on overall survival. (A) Kaplan–Meier survival curves of four groups of patients (AT ≥40%: those who had a transplant and those who did not; AT

Figure 3.

Accuracy of AT (percentage of predicted peak VO2) and individual risk factors in predicting all-cause mortality.

Figure 4.

ROC curve of model 1 for predicting all-cause mortality.

Figure 5.

ROC curve of model 2 for predicting all-cause mortality.