VO2peak prior to transplant differentiates survival post kidney transplant

Abstract

The OPTN/UNOS utilizes the calculated estimated posttransplant survival (EPTS) score as the measure of post-kidney transplant survival to guide allocation of deceased donor kidney transplantation. This score does not include any metric of functional capacity. Peak oxygen uptake (VO_2peak ), is an established predictor of survival among both the general and diseased populations. We assessed the association and discriminative capacity of VO_2peak and that of EPTS score and all-cause mortality post-kidney transplant. Additionally, we assessed the "mortality risk" lower VO_2peak conferred on those patients with low EPTS score. Among a cohort of 293 transplant recipients with at least 3-years post-transplant follow-up, the median VO_2peak was 15.0 ml/Kg/min. Lower pre-transplant VO_2peak and higher EPTS score conferred higher risk of post-transplant mortality. Among the cohort of "low-risk" patients (patients with EPTS score < 50) those with lower VO_2peak had significantly higher risk of mortality (log rank p = 0.045). In fact, the mortality risk among those with low-EPTS (< 50) and low VO_2peak < 12 ml/Kg/min was equivalent to those with high EPTS (> 80) score. We concluded functional capacity as defined by VO_2peak is an important reflection of post-transplant survival. VO_2peak is able to identify those with low EPTS who have similar survival to that of high EPTS phenotype.

Keywords: exercise capacity; frailty; mortality.