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

Paving the Way for Personalized Medicine in First Kidney Transplantation: Interest of a Creatininemia Latent Class Analysis in Early Post-transplantation

Plasma creatinine is a marker of interest in renal transplantation but data on its kinetics in the first days following transplantation are scarce. The aim of this study was to identify clinically relevant subgroups of creatinine trajectories following renal transplantation and to test their association with graft outcome. Among 496 patients with a first kidney transplant included in the French ASTRE cohort at the Poitiers University hospital, 435 patients from donation after brain death were considered in a latent class modeling. Four distinct classes of creatinine trajectories were identified: "poor recovery" (6% of patients), "intermediate recovery" (47%), "good recovery" (10%) and "optimal recovery" (37%). Cold ischemia time was significantly lower in the "optimal recovery" class. Delayed graft function was more frequent and the number of hemodialysis sessions was higher in the "poor recovery" class. Incidence of graft loss was significantly lower in "optimal recovery" patients with an adjusted risk of graft loss 2.42 and 4.06 times higher in "intermediate recovery" and "poor recovery" patients, respectively. Our study highlights substantial heterogeneity in creatinine trajectories following renal transplantation that may help to identify patients who are more likely to experience a graft loss.

Impact of measured versus estimated glomerular filtration rate-based screening on living kidney donor characteristics: A study of multiple cohorts

Background

Most transplant centers in the Netherlands use estimated glomerular filtration rate (eGFR) for evaluation of potential living kidney donors. Whereas eGFR often underestimates GFR, especially in healthy donors, measured GFR (mGFR) allows more precise kidney function assessment, and therefore holds potential to increase the living donor pool. We hypothesized that mGFR-based donor screening leads to acceptance of donors with lower pre-donation eGFR than eGFR-based screening.

Methods

In this longitudinal cohort study, we compared eGFR (CKD-EPI) before donation in one center using mGFR-based screening (mGFR-cohort, n = 250) with two centers using eGFR-based screening (eGFR-cohort1, n = 466 and eGFR-cohort2, n = 160). We also compared differences in eGFR at five years after donation.

Results

Donor age was similar among the cohorts (mean±standard deviation (SD) mGFR-cohort 53±10 years, eGFR-cohort1 52±13 years, P = 0.16 vs. mGFR-cohort, and eGFR-cohort2 53±9 years, P = 0.61 vs. mGFR-cohort). Estimated GFR underestimated mGFR by 10±12 mL/min/1.73m² (mean±SD), with more underestimation in younger donors. In the overall cohorts, mean±SD pre-donation eGFR was lower in the mGFR-cohort (91±13 mL/min/1.73m²) than in eGFR-cohort1 (93±15 mL/min/1.73m², P<0.05) and eGFR-cohort2 (94±12 mL/min/1.73m², P<0.05). However, these differences disappeared when focusing on more recent years, which can be explained by acceptance of more older donors with lower pre-donation eGFR over time in both eGFR-cohorts. Five years post-donation, mean±SD eGFR was similar among the centers (mGFR-cohort 62±12 mL/min/1.73m², eGFR-cohort1 61±14 mL/min/1.73m², eGFR-cohort2 62±11 mL/min/1.73m², P = 0.76 and 0.95 vs. mGFR-cohort respectively). In the mGFR-cohort, 38 (22%) donors were excluded from donation due to insufficient mGFR with mean±SD mGFR of 71±9 mL/min/1.73m².

Conclusions

Despite the known underestimation of mGFR by eGFR, we did not show that the routine use of mGFR in donor screening leads to inclusion of donors with a lower pre-donation eGFR. Therefore eGFR-based screening will be sufficient for the majority of the donors. Future studies should investigate whether there is a group (e.g. young donors with insufficient eGFR) that might benefit from confirmatory mGFR testing.

The Role of Registries in Kidney Transplantation Across International Boundaries

Transplant professionals strive to improve domestic kidney transplantation rates safely, cost efficiently, and ethically, but to increase rates further may wish to allow their recipients and donors to traverse international boundaries. Travel for transplantation presents significant challenges to the practice of transplantation medicine and donor medicine, but can be enhanced if sustainable international registries develop to include low- and low-middle income countries. Robust data collection and sharing across registries, linking pretransplant information to post-transplant information, linking donor to recipient information, increasing living donor transplant activity through paired exchange, and ongoing reporting of results to permit flexibility and adaptability to changing clinical environments, will all serve to enhance kidney transplantation across international boundaries.

Prediction of measured GFR after living kidney donation from pre-donation parameters

BACKGROUND

One of the challenges in living kidney donor screening is to estimate remaining kidney function after donation. Here we developed a new model to predict post-donation measured glomerular filtration rate (mGFR) from pre-donation serum creatinine, age and sex.

METHODS

In the prospective development cohort (TransplantLines, n = 511), several prediction models were constructed and tested for accuracy, precision and predictive capacity for short- and long-term post-donation 125I-iothalamate mGFR. The model with optimal performance was further tested in specific high-risk subgroups (pre-donation eGFR <90 mL/min/1.73 m2, a declining 5-year post-donation mGFR slope or age >65 years) and validated in internal (n = 509) and external (Mayo Clinic, n = 1087) cohorts.

RESULTS

In the development cohort, pre-donation estimated GFR (eGFR) was 86 ± 14 mL/min/1.73 m2 and post-donation mGFR was 64 ± 11 mL/min/1.73 m2. Donors with a pre-donation eGFR ≥90 mL/min/1.73 m2 (present in 43%) had a mean post-donation mGFR of 69 ± 10 mL/min/1.73 m2 and 5% of these donors reached an mGFR <55 mL/min/1.73 m2. A model using pre-donation serum creatinine, age and sex performed optimally, predicting mGFR with good accuracy (mean bias 2.56 mL/min/1.73 m2, R2 = 0.29, root mean square error = 11.61) and precision [bias interquartile range (IQR) 14 mL/min/1.73 m2] in the external validation cohort. This model also performed well in donors with pre-donation eGFR <90 mL/min/1.73 m2 [bias 0.35 mL/min/1.73 m2 (IQR 10)], in donors with a negative post-donation mGFR slope [bias 4.75 mL/min/1.73 m2 (IQR 13)] and in donors >65 years of age [bias 0.003 mL/min/1.73 m2 (IQR 9)].

CONCLUSIONS

We developed a novel post-donation mGFR prediction model based on pre-donation serum creatinine, age and sex.

Factors Associated with the Willingness to Become a Living Kidney Donor: A National Cross-Sectional Study

Introduction: Living donor kidney transplantation is the preferred method of treating kidney failure. The donor agrees to undergo an elective procedure for the benefit of the recipient. Aim: To assess the attitude toward living kidney donation and to investigate the factors that contribute to kidney donation willingness. Methods: A cross-sectional study was carried out between December 2020 and February 2021. The study covered a representative group of 953 Poles aged 18−77, living in all Polish voivodships. The relationship between sociodemographic factors, personal values (Personal Values List), the total score of life satisfaction (Satisfaction with Life Scale) and the willingness to donate a kidney to another human was assessed using a logistic regression model. Results: The most frequently chosen personal values were: good health; physical and mental fitness; love and friendship; knowledge and wisdom. The most frequently chosen symbols of happiness were: good health, successful family life, being needed by others. The median satisfaction with life for the entire group was 20 [16; 24]. Voluntary donation of a kidney to another human being i.e., family, friends, strangers were more often declared by women (OR = 1.21; Cl95%: 1.03−1.42), for whom the most important symbol of happiness was a life full of adventures, travels (OR = 1.39; Cl95%: 1.06−1.82) and the most important personal value was goodness and tenderness (OR = 1.21; Cl95%: 1.05−1.40). Total scores of The Satisfaction with Life Scale correlated positively with the willingness to voluntarily donate a kidney (OR = 1.03; Cl95%: 1.003−1.06), while age correlated negatively (OR = 0.99; Cl95%: 0.98−0.99). Conclusions: Respondents who declare their willingness to be a living kidney donor are mainly female, for which the most important symbol of happiness is a life full of adventures and travel, and the most important values are personal goodness and tenderness. The desire to donate a kidney to another person decreases with age and grows with life satisfaction. Trial registration: ClinicalTrials.gov (ID: NCT04789122).

Age-adapted percentiles of measured glomerular filtration in healthy individuals: extrapolation to living kidney donors over 65 years

OBJECTIVES

Most data on glomerular filtration rate (GFR) originate from subjects <65 years old, complicating decision-making in elderly living kidney donors. In this retrospective multi-center study, we calculated percentiles of measured GFR (mGFR) in donors <65 years old and extrapolated these to donors ≥65 years old.

METHODS

mGFR percentiles were calculated from a development cohort of French/Belgian living kidney donors <65 years (n=1,983), using quantiles modeled as cubic splines (two linear parts joining at 40 years). Percentiles were extrapolated and validated in an internal cohort of donors ≥65 years (n=147, France) and external cohort of donors and healthy subjects ≥65 years (n=329, Germany, Sweden, Norway, France, The Netherlands) by calculating percentages within the extrapolated 5th-95th percentile (P5-P95).

RESULTS

Individuals in the development cohort had a higher mGFR (99.9 ± 16.4 vs. 86.4 ± 14 and 82.7 ± 15.5 mL/min/1.73 m²) compared to the individuals in the validation cohorts. In the internal validation cohort, none (0%) had mGFR below the extrapolated P5, 12 (8.2%) above P95 and 135 (91.8%) between P5-P95. In the external validation cohort, five subjects had mGFR below the extrapolated P5 (1.5%), 25 above P95 (7.6%) and 299 (90.9%) between P5-P95.

CONCLUSIONS

We demonstrate that extrapolation of mGFR from younger donors is possible and might aid with decision-making in elderly donors.

Shift in Living Kidney Donor Demographics Over the Past 50 Years in a German Transplant Center

Background

Living kidney donors may face health risks after donation. Age, sex, body mass index, comorbidities, and relationship to the recipient have an impact on lifetime living kidney donor risk. In view of a changing landscape in renal transplantation with increasing organ shortages, the selection criteria for potential donors may have changed over time.

Material/Methods

We investigated donor demographics and outcomes in a cohort of 760 living kidney donors who donated from 1967 to 2016 at the transplant center in Heidelberg, Germany.

Results

The living kidney donor age increased from 34.9±11.5 to 53.2±10.2 years, with 11.4% donors aged 65 years in the period from 2011 to 2016. The number of donors with comorbidities at the time of donation increased. The percentage of donors with a history of obesity, hypertension, smoking, and a family history of kidney disease enlarged to 18.6%, 36.1%, 37.0%, and 9.1%, respectively. De novo hypertension was a common problem in more than half of the donors at long-term follow-up, and donor renal function decreased about 30 mL/mi/1.73 m².

Conclusions

This detailed analysis of living kidney donor demographics over the last 50 years detected an increased proportion of donors with higher age and comorbidities today. Careful donor selection, regular follow-up visits, and systematic donor registries are required to further improve donor outcomes.

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.

Outcomes in Living Donor Kidney Transplantation: The Role of Donor's Kidney Function

INTRODUCTION

Living donor kidney transplant (LDKT) is one of the best therapeutic options for end-stage kidney disease (ESKD). Guidelines identify different estimated glomerular filtration rate (eGFR) thresholds to determine the eligibility of donors. The aim of our study was to evaluate whether pretransplant donor eGFR was associated with kidney function in the recipient.

METHODS

We retrospectively studied LDKT recipients who received a kidney graft between September 1, 2005, and June 30, 2016 in the same transplant center in France and that had eGFR data available at 3, 12, 24, and 36 months posttransplant.

RESULTS

We studied 90 donor-recipient pairs. The average age at time of transplant was 51.47 ± 10.95 for donors and 43.04 ± 13.52 years for recipients. Donors' average eGFR was 91.99 ± 15.37 mL/min/1.73 m2. Donor's age and eGFR were significantly correlated (p < 0.0001, r2 0.023). Donor's age and eGFR significantly correlated with recipient's eGFR at 3, 12, and 24 months posttransplant (age: p < 0.001 at all intervals; eGFR p = 0.001, 0.003, and 0.016, respectively); at 36 months, only donor's age significantly correlated with recipient's eGFR. BMI, gender match, and year of kidney transplant did not correlate with graft function. In the multivariable analyses, donor's eGFR and donor's age were found to be associated with graft function; correlation with eGFR was lost at 36 months; and donor's age retained a strong correlation with graft function at all intervals (p < 0.001).

CONCLUSIONS

Donor's eGFR and age are strong predictors of recipient's kidney function at 3 years. We suggest that donor's eGFR should be clinically balanced with other determinants of kidney function and in particular with age.

Has the UK living kidney donor population changed over time? A cross-sectional descriptive analysis of the UK living donor registry between 2006 and 2017

BACKGROUND

A living-donor kidney transplant is the best treatment for most people with kidney failure. Population cohort studies have shown that lifetime living kidney donor risk is modified by sex, age, ethnicity, body mass index (BMI), comorbidity and relationship to the recipient.

OBJECTIVES

We investigated whether the UK population of living kidney donors has changed over time, investigating changes in donor demographics.

DESIGN

We undertook a cross-sectional analysis of the UK living kidney donor registry between January 2006 to December 2017. Data were available on living donor sex, age, ethnicity, BMI, hypertension and relationship to recipient.

SETTING

UK living donor registry.

PARTICIPANTS

11 651 consecutive living kidney donors from January 2006 to December 2017.

OUTCOME MEASURES

Living kidney donor demographic characteristics (sex, age, ethnicity, BMI and relationship to the transplant recipient) were compared across years of donation activity. Donor characteristics were also compared across different ethnic groups.

RESULTS

Over the study period, the mean age of donors increased (from 45.8 to 48.7 years, p<0.001), but this change appears to have been limited to the White population of donors. Black donors were younger than White donors, and a greater proportion were siblings of their intended recipient and male. The proportion of non-genetically related non-partner donations increased over the 12-year period of analysis (p value for linear trend=0.002).

CONCLUSIONS

The increasing age of white living kidney donors in the UK has implications for recipient and donor outcomes. Despite an increase in the number of black, Asian and minority ethnic individuals waitlisted for a kidney transplant, there has been no increase in the ethnic diversity of UK living kidney donors. Black donors in the UK may be at a much greater risk of developing kidney failure due to accumulated risks: whether these risks are being communicated needs to be investigated.