Higher mortality risk among kidney transplant recipients than among estimated glomerular filtration rate-matched patients with CKD-preliminary results

Abstract

Background: Although kidney transplantation prolongs survival relative to dialysis, it is associated with a higher death rate than in the general population. The objective of the present study was to assess and compare the risk of mortality and frequency of non-lethal cardiovascular (CV) events in kidney transplant recipients (KTRs) beyond 1 year after successful transplantation versus patients with chronic kidney disease (CKD) using propensity score-matched analysis of estimated glomerular filtration rate (eGFR) and other parameters.

Methods: After propensity score matching, we studied 340 KTRs from the French Données Informatisées et Validées en Transplantation cohort and 605 non-transplant patients with CKD (CKDps) from the French Chronic Kidney Disease-Renal Epidemiology and Information Network cohort. The mean ± standard deviation eGFR was 42 ± 13 and 41 ± 12 mL/min/ 1.73 m2, respectively (P = 0.649). Descriptive data were completed by a survival analysis with Cox regression models.

Results: After a median follow-up period of 2.8 years (KTRs 2.0 years, CKDp 2.9 years), 71 deaths were recorded (31 and 40 in the KTR and CKD groups, respectively). Univariate analysis showed that KTRs had a significantly greater risk of mortality than CKDps. In multivariable analysis, KTRs were found to have a 2.7-fold greater risk of mortality [hazard ratio 2.7 (95% confidence interval 1.6-4.7); P = 0.005]. There was no between-group difference concerning the risk of CV events (P = 0.448). CV death rates in KTRs (29.0%) approximated those of CKDps (22.5%), whereas death rates due to infections were higher in KTRs (19.4% versus 10.0%).

Conclusion: Beyond 1 year after transplantation, KTRs, who possibly had a longer CKD history, had a significantly greater mortality risk than eGFR-matched CKDps. The excess risk was not associated with CV events.

Keywords: cardiovascular; chronic kidney disease; kidney transplantation; mortality.