Risk of end stage kidney disease in kidney transplant recipients versus patients with native chronic kidney disease. Multicenter unmatched and propensity-score matched analyses

Background: In kidney transplant recipients (KTRs), the ESKD risk dependent on the risk factors acting in native CKD remains undefined. Methods: We compared risk and determinants of ESKD between 757 adult KTRs and 1940 patients with native CKD before and after propensity-score (PS) analysis matched for unmodifiable risk factors (age, sex, diabetes, cardiovascular disease and eGFR). Results: In unmatched cohorts, eGFR was lower in CKD vs KTRs (45.9±11.3 vs 59.2±13.4 mL/min/1.73m2, P<0.001). During a median follow-up of 5.4 years, the unadjusted cumulative incidence of ESKD was consistently lower in unmatched KTR vs CKD. Conversely, in PS-matched analysis, the risk of ESKD in KTR was 78% lower vs CKD at one year of follow-up while progressively increased over time resulting similar to that of native CKD patients after 5 years, and 2.3-fold higher than that observed in CKD at 10 years. R2 analysis in unmatched patients showed that the proportion of the outcome variance explained by traditional ESKD determinants was smaller in KTRs vs native CKD (31% vs 70%). After PS matching, the risk of ESKD (HR, 95%CI) was significantly associated with systolic blood pressure (1.02, 1.01-1.02), phosphorus (1.31, 1.05-1.64), 24h proteinuria (1.11, 1.05-1.17) and hemoglobin (0.85, 0.78-0.93) irrespective of KTR status. Similar data were obtained after matching also for modifiable risk factors. Conclusions: In KTRs, when compared with matched native CKD patients, the risk of ESKD is lower in the first 5 years and higher later on. Traditional determinants of ESKD account for one-third of variability of time-to-graft failure.