Higher Mortality in Kidney Transplant Recipients Versus Matched CKD Patients

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Beyond the first year, kidney transplant recipients (KTRs) have an excess risk of mortality, compared to matched chronic kidney disease (CKD) patients who do not undergo kidney transplantation, reports a preliminary study in Nephrology Dialysis Transplantation.

The analysis included patients from two French multicenter prospective cohorts: 340 KTRs and 605 nontransplant CKD patients. The groups were matched on a propensity score incorporating six outcome-dependent variables assessed at cohort enrollment, including estimated glomerular filtration rate (eGFR). Mean eGFR at inclusion was 42 and 41 mL/min/1.73 m2, respectively. All-cause mortality was compared between groups, with cardiovascular events as a secondary outcome.

As expected, patients receiving a kidney transplant were younger: median age 60 years, compared to 66 years in the nontransplant CKD group. Patients in the KTR group may have had a longer duration of CKD. Median duration of follow-up was 2.03 versus 2.92 years, respectively.

All-cause mortality was 9% in the KTR group versus 7% in the CKD comparison group. On univariate analysis, KTRs were at significantly higher risk of death: hazard ratio (HR) 1.70. Other factors associated with mortality were older age, diabetes, history of cardiovascular (CV) disease, and lower eGFR at inclusion. Proteinuria was not a significant factor.

The association between KTR status and death remained significant on multivariate analysis: HR 2.7. The two groups were similar in terms of CV event rate and risk of death due to CV events: 29.0% in the KTR group and 22.5% in non-transplant CKD patients. There was a possible increase in the risk of death due to infection among KTRs: 19.4% versus 10.0%.

Kidney transplantation leads to prolonged survival, compared to dialysis. However, KTRs remain at higher risk of death than healthy people, especially in the first year after transplantation. Most studies of the effects of kidney transplantation on mortality and CV events have compared KTRs with the general population or with wait-listed dialysis patients.

The new analysis suggests that KTRs have a 2.7-fold increase in all-cause mortality beyond the first year posttransplant, compared to matched nontransplant CKD patients. The incidence of CV events is similar between groups, but KTRs may be at higher risk of severe infections. The researchers conclude: “In view of the excess mortality after kidney transplantation, preventing CKD and slowing its progression remain an absolute priority” [Cheddani L, et al. Higher mortality risk among kidney transplant recipients than among estimated glomerular filtration rate–matched patients with CKD—preliminary results. Nephrol Dial Transpl 2020; DOI: 0.1093/ndt/gfaa026].