Temporal trends in the quality of deceased donor kidneys and kidney transplant outcomes in Europe: an analysis by the ERA-EDTA Registry

Abstract

Background: We investigated 10-year trends in deceased donor kidney quality expressed as the kidney donor risk index (KDRI) and subsequent effects on survival outcomes in a European transplant population.

Methods: Time trends in the crude and standardized KDRI between 2005 and 2015 by recipient age, sex, diabetic status and country were examined in 24 177 adult kidney transplant recipients in seven European countries. We determined 5-year patient and graft survival probabilities and the risk of death and graft loss by transplant cohort (Cohort 1: 2005-06, Cohort 2: 2007-08, Cohort 3: 2009-10) and KDRI quintile.

Results: The median crude KDRI increased by 1.3% annually, from 1.31 [interquartile range (IQR) 1.08-1.63] in 2005 to 1.47 (IQR 1.16-1.90) in 2015. This increase, i.e. lower kidney quality, was driven predominantly by increases in donor age, hypertension and donation after circulatory death. With time, the gap between the median standardized KDRI in the youngest (18-44 years) and oldest (>65 years) recipients widened. There was no difference in the median standardized KDRI by recipient sex. The median standardized KDRI was highest in Austria, the Netherlands and the Basque Country (Spain). Within each transplant cohort, the 5-year patient and graft survival probability were higher for the lowest KDRIs. There was no difference in the patient and graft survival outcomes across transplant cohorts, however, over time the survival probabilities for the highest KDRIs improved.

Conclusions: The overall quality of deceased donor kidneys transplanted between 2005 and 2015 has decreased and varies between age groups and countries. Overall patient and graft outcomes remain unchanged.

Keywords: deceased donors; epidemiology; survival outcomes; transplantation.

FIGURE 1

Violin plots of the crude KDRI for the transplant years 2005, 2010 and 2015 for all countries combined presented as overall (left upper panel), by recipient sex (right upper panel), by recipient age group (left lower panel) and by recipient diabetic status (right lower panel). Black circle indicates the median KDRI and the yellow diamond the mean KDRI.

FIGURE 2

Standardized median KDRI and AAPC (95% CI) during the years 2005–15 for (A) all countries/regions combined and by (B) recipient sex, (C) recipient age group and (D) recipient diabetic status. The KDRI is scaled relative to the median kidney donor in 2005. AAPCs with a significance level <0.05 are denoted by an asterisk (*).

FIGURE 3

Standardized median KDRI and AAPC (95% CI) during the years 2005–15 by country/region. The KDRI is scaled relative to the median kidney donor in 2005 for all countries combined.

FIGURE 4

Five-year unadjusted patient survival curves for patients ≥18 years of age receiving their first deceased donor kidney-only transplant by (A) time cohort during 2005 and 2010 and by KDRI quintiles between (B) 2005 and 2006, (C) 2007 and 2008 and (D) 2009 and 2010 in all countries combined and 5-year unadjusted graft survival curves by (E) time cohort during 2005 and 2010 and by KDRI quintiles between (F) 2005 and 2006, (G) 2007 and 2008 and (H) 2009 and 2010 for all countries/regions combined.

FIGURE 5

Five-year risk and 95% CI of (A) unadjusted and (B) adjusted death and 5-year risk of (A) unadjusted and (B) adjusted graft failure by time cohort (2005–06, 2007–08, 2009–10) for all countries/regions combined. Adjustments made for recipient age at transplantation, recipient sex, primary kidney disease, CIT, HLA mismatch score and the country of transplantation.