Donor-Recipient Relationship and Risk of ESKD in Live Kidney Donors of Varied Racial Groups

Hypertension and Kidney Function After Living Kidney Donation

Importance

Recent guidelines call for better evidence on health outcomes after living kidney donation.

Objective

To determine the risk of hypertension in normotensive adults who donated a kidney compared with nondonors of similar baseline health. Their rates of estimated glomerular filtration rate (eGFR) decline and risk of albuminuria were also compared.

Design, Setting, and Participants

Prospective cohort study of 924 standard-criteria living kidney donors enrolled before surgery and a concurrent sample of 396 nondonors. Recruitment occurred from 2004 to 2014 from 17 transplant centers (12 in Canada and 5 in Australia); follow-up occurred until November 2021. Donors and nondonors had the same annual schedule of follow-up assessments. Inverse probability of treatment weighting on a propensity score was used to balance donors and nondonors on baseline characteristics.

Exposure

Living kidney donation.

Main Outcomes and Measures

Hypertension (systolic blood pressure [SBP] ≥140 mm Hg, diastolic blood pressure [DBP] ≥90 mm Hg, or antihypertensive medication), annualized change in eGFR (starting 12 months after donation/simulated donation date in nondonors), and albuminuria (albumin to creatinine ratio ≥3 mg/mmol [≥30 mg/g]).

Results

Among the 924 donors, 66% were female; they had a mean age of 47 years and a mean eGFR of 100 mL/min/1.73 m2. Donors were more likely than nondonors to have a family history of kidney failure (464/922 [50%] vs 89/394 [23%], respectively). After statistical weighting, the sample of nondonors increased to 928 and baseline characteristics were similar between the 2 groups. During a median follow-up of 7.3 years (IQR, 6.0-9.0), in weighted analysis, hypertension occurred in 161 of 924 donors (17%) and 158 of 928 nondonors (17%) (weighted hazard ratio, 1.11 [95% CI, 0.75-1.66]). The longitudinal change in mean blood pressure was similar in donors and nondonors. After the initial drop in donors' eGFR after nephrectomy (mean, 32 mL/min/1.73 m2), donors had a 1.4-mL/min/1.73 m2 (95% CI, 1.2-1.5) per year lesser decline in eGFR than nondonors. However, more donors than nondonors had an eGFR between 30 and 60 mL/min/1.73 m2 at least once in follow-up (438/924 [47%] vs 49/928 [5%]). Albuminuria occurred in 132 of 905 donors (15%) and 95 of 904 nondonors (11%) (weighted hazard ratio, 1.46 [95% CI, 0.97-2.21]); the weighted between-group difference in the albumin to creatinine ratio was 1.02 (95% CI, 0.88-1.19).

Conclusions and Relevance

In this cohort study of living kidney donors and nondonors with the same follow-up schedule, the risks of hypertension and albuminuria were not significantly different. After the initial drop in eGFR from nephrectomy, donors had a slower mean rate of eGFR decline than nondonors but were more likely to have an eGFR between 30 and 60 mL/min/1.73 m2 at least once in follow-up.

Trial Registration

ClinicalTrials.gov Identifier: NCT00936078.

Subsistence of sib altruism in different mating systems and Haldane's arithmetic

The moral rule "Risk your life to save your family members" is, at the same time, a biological phenomenon. The prominent population geneticist, J.B.S. Haldane told his friends that he would risk his life to save two drowning brothers, but not one - so the story goes. In biological terms, Haldane's arithmetic claims that sib altruism is evolutionarily rational, whenever by "self-sacrifice" an altruistic gene "rescues", on average, more than one copy of itself in its lineage. Here, we derive conditions for evolutionary stability of sib altruism, using population genetic models for three mating systems (monogamy, promiscuity and polygyny) with linear and non-linear group effect on the siblings' survival rate. We show that for all considered selection situations, the condition of evolutionary stability is equivalent to Haldane's arithmetic. The condition for evolutionary stability is formulated in terms of genetic relatedness and the group effect on the survival probability, similarly to the classical Hamilton's rule. We can set up a "scale of mating systems", since in pairwise interactions the chance of evolutionary stability of sib altruism decreases in this order: monogamy, polygyny and promiscuity. Practice of marrying and siblings' solidarity are moral rules in a secular world and in various religious traditions. These moral rules are not evolutionarily independent, in the sense that the subsistence of sib altruism is more likely in a monogamous population.

The impact of COVID-19 on kidney transplant care

The SARS-CoV-2 virus precipitated the coronavirus 2019 (COVID-19) pandemic, which placed considerable strain on healthcare systems and necessitated immediate and rapid alterations in the delivery of healthcare. In the transplant population, COVID-19 directly impacts an inherently vulnerable population in the setting of immunosuppression and co-morbidities, but also further complicates the clinical evaluation and management of kidney transplant candidates and recipients in a strained healthcare environment being challenged by the pandemic. Many transplant centers around the world saw mortality rate spikes in organ recipients related to COVID-19, and changes in care delivery abound. This review evaluates the care of the kidney transplant patient through all phases of the process including pre-operative evaluations, perioperative care, post-transplantation considerations, and how the global pandemic has changed the way we care for our patients.

The Living Kidney Donor Safety Study: Protocol of a Prospective Cohort Study

Background

Living kidney donation is considered generally safe in healthy individuals; however, there is a need to better understand the long-term effects of donation on blood pressure and kidney function.

Objectives

To determine the risk of hypertension in healthy, normotensive adults who donate a kidney compared with healthy, normotensive non-donors with similar indicators of baseline health. We will also compare the 2 groups on the rate of decline in kidney function, the risk of albuminuria, and changes in health-related quality of life.

Design Participants and Setting

Prospective cohort study of 1042 living kidney donors recruited before surgery from 17 transplant centers (12 in Canada and 5 in Australia) between 2004 and 2014. Non-donor participants (n = 396) included relatives or friends of the donor, or donor candidates who were ineligible to donate due to blood group or cross-match incompatibility. Follow-up will continue until 2021, and the main analysis will be performed in 2022. The anticipated median (25th, 75th percentile, maximum) follow-up time after donation is 7 years (6, 8, 15).

Measurements

Donors and non-donors completed the same schedule of measurements at baseline and follow-up (non-donors were assigned a simulated nephrectomy date). Annual measurements were obtained for blood pressure, estimated glomerular filtration rate (eGFR), albuminuria, patient-reported health-related quality of life, and general health.

Outcomes

Incident hypertension (a systolic/diastolic blood pressure ≥ 140/90 mm Hg or receipt of anti-hypertensive medication) will be adjudicated by a physician blinded to the participant's donation status. We will assess the rate of change in eGFR starting from 12 months after the nephrectomy date and the proportion who develop an albumin-to-creatinine ratio ≥3 mg/mmol (≥30 mg/g) in follow-up. Health-related quality of life will be assessed using the 36-item RAND health survey and the Beck Anxiety and Depression inventories.

Limitations

Donation-attributable hypertension may not manifest until decades after donation.

Conclusion

This prospective cohort study will estimate the attributable risk of hypertension and other health outcomes after living kidney donation.

Examining post-donation outcomes in Hispanic/Latinx living kidney donors in the United States: A systematic review

We conducted a systematic review to assess outcomes in Hispanic donors and explore how Hispanic ethnicity was characterized. We searched PubMed, EMBASE, and Scopus through October 2021. Two reviewers independently screened study titles, abstracts, and full texts; they also qualitatively synthesized results and independently assessed quality of included studies. Eighteen studies met our inclusion criteria. Study sample sizes ranged from 4007 to 143,750 donors and mean age ranged from 37 to 54 years. Maximum follow-up time of studies varied from a perioperative donor nephrectomy period to 30 years post-donation. Hispanic donors ranged between 6% and 21% of the donor populations across studies. Most studies reported Hispanic ethnicity under race or a combined race and ethnicity category. Compared to non-Hispanic White donors, Hispanic donors were not at increased risk for post-donation mortality, end-stage kidney disease, cardiovascular disease, non-pregnancy-related hospitalizations, or overall perioperative surgical complications. Compared to non-Hispanic White donors, most studies showed Hispanic donors were at higher risk for diabetes mellitus following nephrectomy; however, mixed findings were seen regarding the risk for post-donation chronic kidney disease and hypertension. Future studies should evaluate cultural, socioeconomic, and geographic differences within the heterogeneous Hispanic donor population, which may further explain variation in health outcomes.

The Scope of Telemedicine in Kidney Transplantation: Access and Outreach Services

Access to transplant centers is a key barrier for kidney transplant evaluation and follow-up care for both the recipient and donor. Potential kidney transplant recipients and living kidney donors may face geographic, financial, and logistical challenges in engaging with a transplant center and maintaining post-transplant continuity of care. Telemedicine via synchronous video visits has the potential to overcome the access barrier to transplant centers. Transplant centers can start the evaluation process for potential recipients and donors via telemedicine, especially for those who have challenges to come for an in-person visit or when there are restrictions on clinic capacities, such as during a pandemic. Similarly, transplant centers can use telemedicine to sustain post-transplant follow-up care while avoiding the burden of travel and its associated costs. However, expansion to telemedicine-based kidney transplant services is substantially dependent on telemedicine infrastructure, insurer policy, and state regulations. In this review, we discuss the practice of telemedicine in kidney transplantation and its implications for expanding access to kidney transplant services and outreach from pretransplant evaluation to post-transplant follow-up care for the recipient and donor.

Sequential genetic testing of living-related donors for inherited renal disease to promote informed choice and enhance safety of living donation

Living kidney donors (LKDs) with a family history of renal disease are at risk of kidney disease as compared to LKDs without such history suggesting that some LKDs may be pre-symptomatic for monogenic kidney disease. LKDs with related transplant candidates whose kidney disease was considered genetic in origin were selected for genetic testing. In each case, the transplant candidate was first tested to verify the genetic diagnosis. A genetic diagnosis was confirmed in 12 of 24 transplant candidates (ADPKD-PKD1: 6, ALPORT-COL4A3: 2, ALPORT-COL4A5: 1: nephronophthisis-SDCCAG8: 1; CAKUT-HNF1B and ADTKD-MUC1: 1 each) and 2 had variants of unknown significance (VUS) in phenotype-relevant genes. Focused genetic testing was then done in 20 of 34 LKDs. 12 LKDs screened negative for the familial variant and were permitted to donate; seven screened positive and were counseled against donation. One, the heterozygous carrier of a recessive disorder was also cleared. Six of seven LKDs with a family history of ADPKD were under 30 years and in 5, by excluding ADPKD, allowed donation to safely proceed. The inclusion of genetic testing clarified the diagnosis in recipient candidates, improving safety or informed decision-making in LKDs.

Marginal parent donors-Process and ethics

BACKGROUND

Pre-emptive kidney transplantation for end-stage kidney disease in children has many advantages and may lead to the consideration of marginal parent donors.

METHODS

Using the example of the transplant of a kidney with medullary sponge disease from a parent to the child, we review the ethical framework for working up such donors.

RESULTS

The four principles of health ethics include autonomy (the right of the patient to retain control over his/her own body); beneficence (healthcare providers must do all they can do to benefit the patient in each situation); non-maleficence ("first do no harm"-providers must consider whether other people or society could be harmed by a decision made, even if it is made for the benefit of an individual patient) and justice (there should be an element of fairness in all medical decisions). Highly motivated donors may derive significant psychological benefit from their donation and may thus be willing to incur more risk. The transplantation team and, ideally, an independent donor advocate team must make a judgment about the acceptability of the risk-benefit ratio for particular potential donors, who must also make their own assessment. The transplantation team and donor advocate team must be comfortable with the risk-benefit ratio before proceeding.

CONCLUSIONS

An independent donor advocacy team that focuses on the donor needs is needed with sufficient multidisciplinary ethical, social, and psychological expertise. The decision to accept or reject the donor should be within the authority of the independent donor advocacy team and not the providers or the donor.

Living donation - any news on the donor?

PURPOSE OF REVIEW

Living kidney donation has been an established practice for many years. Although studies from the past decade have uncovered risks to the donor, living kidney donation is still promoted. In this review, the most recent studies are summarized.

RECENT FINDINGS

Retrospective studies with long follow-up have detected an increased risk of hypertension among donors. Donors with hypertension at the time of donation may be at increased risk of adverse outcomes, but results differ. Recent studies have not found increased long-term mortality, but follow-up is short and control groups are of different quality.

SUMMARY

In all, the most recent findings more or less corroborate previous knowledge in the field of living donation. There is still a need for new studies on mortality with appropriate control groups and long enough follow-up.

Association Between Donor-Recipient Biological Relationship and Allograft Outcomes After Living Donor Kidney Transplant

IMPORTANCE

The proportion of living donor kidney transplants from donors unrelated to their recipients is increasing in the US.

OBJECTIVE

To examine the association between donor-recipient biological relationship and allograft survival after living donor kidney transplant.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study used Organ Procurement and Transplantation Network data on US adult living donor kidney transplants (n = 86 154) performed from January 1, 2000, to December 31, 2014, excluding cases in which recipients previously received a kidney transplant (n = 10 342) or key data were missing (n = 2832). Last follow-up was March 20, 2020.

EXPOSURES

Donor-recipient biological relationship.

MAIN OUTCOMES AND MEASURES

The primary outcome was death-censored allograft failure. Univariate and multivariable time-to-event analyses were performed for death-censored allograft failure for the overall cohort, then separately for recipients with and without primary diagnoses of cystic kidney disease and for transplants from African American and non-African American donors.

RESULTS

Among the 72 980 transplant donor and recipients included in the study (median donor age, 41 years; interquartile range [IQR], 32-50 years; 43 990 [60%] female; 50 014 [69%] White), 43 174 (59%) donors and recipients were biologically related and 29 806 (41%) were unrelated. Donors related to their recipients were younger (median [IQR] age, 39 [31-48] vs 44 [35-52] years) and less likely to be female (24 848 [58%] vs 19 142 [64%]) or White (26 933 [62%] vs 23 081 [77%]). Recipients related to their donors were younger (median [IQR] age, 48 [34-58] vs 50 [40-58] years), more likely to be female (18 035 [42%] vs 10 530 [35%]), and less likely to have cystic kidney disease (2530 [6%] vs 4600 [15%]). Related pairs had fewer HLA mismatches overall (median [IQR], 3 [2-3] vs 5 [4-5]). After adjustment for HLA mismatches, donor and recipient characteristics, and transplant era, donor-recipient biological relationship was associated with higher death-censored allograft failure (hazard ratio, 1.05; 95% CI, 1.01-1.10; P = .03). When stratified by primary disease, this association persisted only for recipients without cystic kidney disease. When stratified by donor race, this association persisted only for transplants from African American donors.

CONCLUSIONS AND RELEVANCE

In this cohort study, living donor kidney transplants from donors biologically related to their recipients had higher rates of allograft failure than transplants from donors unrelated to their recipients after HLA matching was accounted for. Further study is needed to determine which genetic or socioenvironmental factors are associated with this finding.

Donor Family History of ESKD and Long-term Outcomes Among African American Living Kidney Donors: A Retrospective Cohort Study

RATIONALE & OBJECTIVE

Live kidney donation is associated with a small increased risk for kidney disease and hypertension in African American donors. We investigated a possible association between donor family history of end-stage kidney disease (ESKD) and their postdonation kidney function and the development of hypertension. We tested whether this association was modified by kidney donation.

STUDY DESIGN

Retrospective cohort.

SETTING & PARTICIPANTS

Former African American live kidney donors between 1993 and 2010. Healthy nondonors were selected from the Coronary Artery Disease in Young Adults (CARDIA) Study.

EXPOSURE

Family history of ESKD in a first-degree relative.

OUTCOMES

Kidney function and blood pressure ≥ 140/90 mm Hg or use of antihypertensive medications at follow-up.

ANALYTICAL APPROACH

Donors were grouped based on family history of ESKD. Outcomes were first compared between donor groups and then between donors and healthy nondonors matched for demographics, follow-up time, and family history. A mixed-effect model was used to compare outcomes.

RESULTS

Of 179 donors, 139 (78%) had a first degree relative with ESKD. Predonation characteristics were similar between the 2 groups. At a median follow-up of 11 years postdonation, there was no difference in postdonation estimated glomerular filtration rates (68 ± 19 vs 69 ± 13 mL/min/1.73 m2; P = 0.71) and the presence of albuminuria (P = 0.16). There was a trend toward a higher incidence of hypertension (51% vs 35%; P = 0.08) among donors with a family history of ESKD than for those without. Although there was no difference in annual change in estimated glomerular filtration rate (P = 0.17), the risk for hypertension was higher in donors than nondonors (relative risk, 2.44 [95% CI, 1.56-3.84]), but there was no interaction by family history (P = 0.11).

LIMITATIONS

Retrospective small study. Lack of data across donor-recipient specific biological relationship.

CONCLUSIONS

Family history of ESKD is not associated with postdonation kidney function among African American kidney donors. Live kidney donation is associated with an increased risk for hypertension among African Americans, independent of donor family history of ESKD.

The first increase in live kidney donation in the United States in 15 years

The first sustained increase in live kidney donation in the United States in 15 years was observed from 2017 to 2019. To help sustain this surge, we studied 35 900 donors (70.3% white, 14.5% Hispanic, 9.3% black, 4.4% Asian) to understand the increase in 2017-2019 vs 2014-2016 using Poisson regression. Among biologically related donors aged <35, 35-49, and ≥50 years, the number of donors did not change across race/ethnicity but increased by 38% and 29% for Hispanic and black ≥50. Among unrelated donors <35, 35-49, and ≥50, white donors increased by 18%, 14%, and 27%; Hispanic donors <35 did not change but increased by 22% and 35% for 35-49 and ≥50; black donors <35 declined by 23% and did not change for 35-49 and ≥50; Asian donors did not change. Among kidney paired donors <35, 35-49, and ≥50, white donors increased by 42%, 50%, and 68%; Hispanic donors <35 and 35-49 increased by 36% and 55% and did not change for ≥50; black donors did not change; Asian donors <35 did not change but increased by 107% and 82% for 35-49 and ≥50. The increase in donation was driven predominantly by unrelated and paired white donors. Donation among unrelated black individuals should be promoted.

Apolipoprotein L1: role in the evaluation of kidney transplant donors

PURPOSE OF REVIEW

To summarize the current state of evidence regarding the role of apolipoprotein L1 (APOL1) genotyping in evaluating donors for kidney transplantation.

RECENT FINDINGS

African ancestry is associated with an increased risk of kidney failure following living donation. Moreover, kidney transplants from African ancestry deceased donors have an increased risk of graft failure. Preliminary evidence suggests that APOL1 genotype may mediate at least a portion of this racial variation, with high-risk APOL1 genotypes defined by presence of two renal risk variants (RRVs). A pilot study 136 African ancestry living donors found that those with APOL1 high-risk genotypes had lower baseline kidney function and faster rates of kidney function decline after donation. To date, three retrospective studies identified a two-to-three times greater risk of allograft failure associated with kidneys from donors with high-risk APOL1 genotype. Active research initiatives seek to address unanswered questions, including reproducibility in large national samples, the role of 'second hits' injuries, and impact of recipient genotype, with a goal to build consensus on applications for policy and practice.

SUMMARY

As evidence evolves, APOL1 genotyping may have applications for organ quality scoring in deceased donor kidney allocation, and for the evaluation and selection of living donor candidates.