Amending a historic paradigm for selecting living kidney donors

Long-term renal and cardiovascular outcome of living kidney donors: A single-center retrospective observation study

Background

The nephrectomy for donation reduces the renal parenchyma and glomerular filtration rate (GFR). It is important to understand the clinical consequences of kidney donation by a living donor.

Methods

In this single-center, observational, retrospective study, we defined the renal and cardiovascular outcomes of living kidney donors. We analyzed data of 124 donors who donated at the Kidney Transplant Center (TC) of Bari between February 2002 and December 2018. Biometric data collected at visit 0, that is, at the time of the study of the donor candidate, and at visit 1, or rather at the last nephrological checkup (October-2018/August-2019) were compared.

Results

An overall drop in GFR of 29 mL/min was observed over the analyzed period of 81+/-59 months. At visit 1, two donors developed chronic renal failure, including one in ESKD who underwent a kidney transplant. No relationship between age at donation and GFR drop was found. A trend toward an increase in obese people was reported; 28% of patients had compensated dyslipidemia and 35% were treated for hypertension. During the follow-up time, 3% had major cardiovascular events and 24% were lost to follow-up. One patient died.

Conclusion

The age of the donor does not represent a basic element for reducing GFR or for the occurrence of major cardiovascular events. Furthermore, older donor candidates, in optimal health, should not be excluded from the donation. It is important to promote careful and timely follow-up of the donor, preventing the most common clinical consequences of nephrectomy, in consideration of the poor compliance of a large part of donors over the long-term post-donation period.

Temporal trends in living kidney donation in France between 2007 and 2017

BACKGROUND

Long-term studies have demonstrated a slight increased risk for end-stage renal disease (ESRD) for living kidney donors (LKD). In France, living kidney donation doubled within the past 10 years. We investigated the change in characteristics of LKD between 2007 and 2017 and the adequacy of follow-up.

METHODS

Data were obtained from the national registry for LKD. We compared characteristics of LKD between two study periods: 2007-11 and 2012-17, and stratified donors by age and relation to recipient. We aggregated four characteristics associated with higher ESRD risk [young age, first-degree relation to recipient, obesity, low glomerular filtration rate (GFR) for age] in a single risk indicator ranging from 0 to 4.

RESULTS

We included 3483 donors. The proportion of unrelated donors >56 years of age increased significantly. The proportion of related donors <56 years of age decreased significantly. The body mass index and proportion of obese donors did not change significantly. The proportion of donors with low estimated GFR for age decreased significantly from 5% to 2.2% (P < 0.001). The proportion of donors with adequate follow-up after donation increased from 19.6% to 42.5% (P < 0.001). No donor had a risk indicator equal to 4, and the proportion of donors with a risk indicator equal to 0 increased significantly from 19.2% to 24.9% (P < 0.001).

CONCLUSIONS

An increase in living kidney donation in France does not seem to be associated with the selection of donors at higher risk of ESRD and the proportion of donors with adequate annual follow-up significantly increased.

Living kidney donor evaluation for all candidates with normal estimated GFR for age

Multiple days assessments are frequent for the evaluation of candidates to living kidney donation, combined with an early GFR estimation (eGFR). Living kidney donation is questionable when eGFR is <90 ml/min/1.73 m² (KDIGO guidelines) or 80 ml/min/1.73 m² (most US centres). However, age-related GFR decline results in a lower eGFR for older candidates. That may limit the number of older kidney donors. Yet, continuing the screening with a GFR measure increases the number of eligible donors. We hypothesized that in-depth screening should be proposed to all candidates with a normal eGFR for age. We compared the evolution of eGFR after donation between three groups of predonation eGFR: normal for age (S_age ) higher than 90 or 80 ml/min/1.73 m² (S₉₀ and S_80, respectively); across three age groups (<45, 45-55, >55 years) in a population of 1825 French living kidney donors with a median follow-up of 5.9 years. In donors younger than 45, postdonation eGFR, absolute- and relative-eGFR variation were not different between the three groups. For older donors, postdonation eGFR was higher in S₉₀ than in S₈₀ or S_age but other comparators were identical. Postdonation eGFR slope was comparable between all groups. Our results are in favour of in-depth screening for all candidates to donation with a normal eGFR for age.

Living Kidney Donor Evaluation

Long-term safety of living kidney donation (LKD), especially for young donors, has become a real matter of concern in the transplant community and may contribute to creating resistance to LKD. In this context, the criteria that govern living donor donations must live up to very demanding standards as well as adjust to this novel reality. In the first part, we review the existing guidelines published after 2010 and critically examine their recommendations to see how they do not necessarily lead to consistent and universal practices in the choice of specific thresholds for a parameter used to accept or reject a living donor candidate. In the second part, we present the emergence of a new paradigm for LKD developed in the 2017 Kidney Disease: Improving Global Outcomes guidelines with the introduction of an integrative risk-based approach. Finally, we focus on predonation renal function evaluation, a criteria that remain central in the selection process, and discuss several issues surrounding the donor candidate's glomerular filtration rate assessment.