Long-term risk of hypertension and chronic kidney disease in living kidney donors

Living kidney donation in a developing country

Background

Living kidney donation has been advocated as a means to ameliorate the chronic shortage of organs for transplantation. Significant rates of comorbidity and familial risk for kidney disease may limit this approach in the local context; there is currently limited data describing living donation in Africa.

Methods

We assessed reasons for non-donation and outcomes following donation in a cohort of 1208 ethnically diverse potential living donors evaluated over a 32-year period at a single transplant centre in South Africa.

Results

Medical contraindications were the commonest reason for donor exclusion. Black donors were more frequently excluded (52.1% vs. 39.3%; p<0.001), particularly for medical contraindications (44% vs. 35%; p<0.001); 298 donors proceeded to donor nephrectomy (24.7%). Although no donor required kidney replacement therapy, an estimated glomerular filtration rate below 60 ml/min/1.73 m2 was recorded in 27% of donors at a median follow-up of 3.7 years, new onset albuminuria >300 mg/day was observed in 4%, and 12.8% developed new-onset hypertension. Black ethnicity was not associated with an increased risk of adverse post-donation outcomes.

Conclusion

This study highlights the difficulties of pursuing live donation in a population with significant medical comorbidity, but provides reassurance of the safety of the procedure in carefully selected donors in the developing world.

Risk for subsequent hypertension and cardiovascular disease after living kidney donation: is it clinically relevant?

The first successful live donor kidney transplant was performed in 1954. Receiving a kidney transplant from a live kidney donor remains the best option for increasing both life expectancy and quality of life in patients with end-stage kidney disease. However, ever since 1954, there have been multiple questions raised on the ethics of live kidney donation in terms of negative impacts on donor life expectancy. Given the close relationship between reduced kidney function in patients with chronic kidney disease (CKD) and hypertension, cardiovascular disease and cardiovascular mortality, information on the impact of kidney donation on these is particularly relevant. In this article, we review the existing evidence, focusing on the more recent studies on the impact of kidney donation on all-cause mortality, cardiovascular mortality, cardiovascular disease and hypertension, as well as markers of cardiovascular damage including arterial stiffness and uraemic cardiomyopathy. We also discuss the similarities and differences between the pathological reduction in renal function that occurs in CKD, and the reduction in renal function that occurs because of a donor nephrectomy. Kidney donors perform an altruistic act that benefits individual patients as well as the wider society. They deserve to have high-quality evidence on which to make informed decisions.

Effects of living kidney donation on arterial stiffness: a systematic review protocol

INTRODUCTION

Kidney donors have been reported to have accelerated progression of aortic stiffness and decreased glomerular filtration compared with healthy non-donors. This is a concern because increased aortic stiffness is an independent predictor of overall cardiovascular disease and all-cause mortality in the general population. To confirm if arterial stiffness increases after donation, we will systematically review all studies that evaluated indices of arterial stiffness in healthy individuals who underwent unilateral nephrectomy for kidney donation compared with age-matched healthy non-nephrectomised controls.

METHODS/ANALYSIS

We will comprehensively search for studies published between 1 January 1960 and 15 March 2021 in MEDLINE, EMBASE, Cochrane Central, OVID and EBM reviews. All prospective (cohort, case-control, case series and before-and-after studies) and retrospective non-randomised studies reporting indices of arterial stiffness in nephrectomised and non-nephrectomised healthy participants will be included. Primary outcome will be the difference in the functional metrics of arterial stiffness between donors and non-donors. Secondary outcomes will be the differences in systolic/diastolic blood pressures, serum creatinine, glomerular filtration, carotid artery intima-media thickness and vascular calcification. Study screening, selection and data extraction will be performed by two independent reviewers. Risk of bias will be independently assessed with the ROBINS-I tool and confidence in evidence by the Grading of Recommendations Assessment, Development and Evaluation recommendations. Qualitative and quantitative data syntheses as well as clinical and statistical heterogeneity (Forest plots, I2 and Cochran's Q statistics) will be evaluated. If clinical and statistical heterogeneity are acceptable, inverse variance-weighted effects will be analysed by random effect models.

ETHICS AND DISSEMINATION

No ethical approval is necessary. Our results will be disseminated through peer-review publication and presentations to guide stakeholders on the evaluation and follow-up care of kidney donors.

PROSPERO REGISTRATION NUMBER

CRD42020185551.

Changes in Blood Pressure and Arterial Hemodynamics following Living Kidney Donation

BACKGROUND AND OBJECTIVES

The Effect of a Reduction in GFR after Nephrectomy on Arterial Stiffness and Central Hemodynamics (EARNEST) study was a multicenter, prospective, controlled study designed to investigate the associations of an isolated reduction in kidney function on BP and arterial hemodynamics.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Prospective living kidney donors and healthy controls who fulfilled criteria for donation were recruited from centers with expertise in vascular research. Participants underwent office and ambulatory BP measurement, assessment of arterial stiffness, and biochemical tests at baseline and 12 months.

RESULTS

A total of 469 participants were recruited, and 306 (168 donors and 138 controls) were followed up at 12 months. In the donor group, mean eGFR was 27 ml/min per 1.73 m² lower than baseline at 12 months. Compared with baseline, at 12 months the mean within-group difference in ambulatory day systolic BP in donors was 0.1 mm Hg (95% confidence interval, -1.7 to 1.9) and 0.6 mm Hg (95% confidence interval, -0.7 to 2.0) in controls. The between-group difference was -0.5 mm Hg (95% confidence interval, -2.8 to 1.7; P=0.62). The mean within-group difference in pulse wave velocity in donors was 0.3 m/s (95% confidence interval, 0.1 to 0.4) and 0.2 m/s (95% confidence interval, -0.0 to 0.4) in controls. The between-group difference was 0.1 m/s (95% confidence interval, -0.2 to 0.3; P=0.49).

CONCLUSIONS

Changes in ambulatory peripheral BP and pulse wave velocity in kidney donors at 12 months after nephrectomy were small and not different from controls.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

NCT01769924 (https://clinicaltrials.gov/ct2/show/NCT01769924).

Blood Pressure and Living Kidney Donors: A Clinical Perspective

Elevated blood pressure (BP), or “hypertension,” has been one of the main exclusion criteria for living kidney donation, as it is a risk factor for renal and cardiovascular disease. The effect of elevated BP in living kidney donors is not well studied or understood. The most current living kidney donation guidelines state that donors with a BP >140/90 mm Hg with 1–2 antihypertensive medications or evidence of end-organ damage should be excluded from living kidney donation. Yet, the definitions of “hypertension” have changed with the release of the American Heart Association (AHA)/American College of Cardiology (ACC) clinical practice guidelines suggesting that 120–129 mm Hg is elevated BP and Stage 1 hypertension is 130 mm Hg. However, the kidney function (in terms of estimated GFR) of “hypertensive” living kidney donors does not fare significantly worse postdonation compared with that of “normotensive” donors. In addition, even though living kidney donation itself is not considered to be a risk factor for developing hypertension, there exist certain risk factors (African American or Hispanic descent, obesity, age) that may increase the risk of living kidney donors developing elevated BP postdonation. The choice of BP targets and medications needs to be carefully individualized. In general, a BP <130/80 mm Hg is needed, along with lifestyle modifications.

Chronic kidney disease as a cardiovascular risk factor: lessons from kidney donors

Chronic kidney disease (CKD) is a major risk factor for cardiovascular disease but is often associated with other risks such as diabetes and hypertension and can be both a cause and an effect of cardiovascular disease. Although epidemiologic data of an independent association of reduced glomerular filtration rate with cardiovascular risk are strong, causative mechanisms are unclear.

Living kidney donors provide a useful model for assessing the “pure” effects of reduced kidney function on the cardiovascular system. After nephrectomy, the glomerular filtration rate ultimately falls by about one-third so many can be classified as having chronic kidney disease stages 2 or 3. This prompts concern based on the data showing an elevated cardiovascular risk with these stages of chronic kidney disease. However, initial data suggested no increase in adverse cardiovascular effects compared with control populations. Recent reports have shown a possible late increase in cardiovascular event rates and an early increase in left ventricular mass and markers of risk such as urate and albuminuria. The long-term significance of these small changes is unknown. More detailed and long-term research is needed to determine the natural history of these changes and their clinical significance.

•

Subjects with chronic kidney disease (CKD) have an elevated risk of cardiovascular disease.

•

Kidney donors have a reduced glomerular filtration rate and biochemical changes similar to CKD subjects.

•

Most studies of donors have not shown an elevated risk of death or cardiac disease.

•

Donors have structural and functional cardiovascular changes similar to early CKD.

•

The clinical significance of these changes is currently unknown.

Validation of Living Donor Nephrectomy Codes

Background:

Use of administrative data for outcomes assessment in living kidney donors is increasing given the rarity of complications and challenges with loss to follow-up.

Objective:

To assess the validity of living donor nephrectomy in health care administrative databases compared with the reference standard of manual chart review.

Design:

Retrospective cohort study.

Setting:

5 major transplant centers in Ontario, Canada.

Patients:

Living kidney donors between 2003 and 2010.

Measurements:

Sensitivity and positive predictive value (PPV).

Methods:

Using administrative databases, we conducted a retrospective study to determine the validity of diagnostic and procedural codes for living donor nephrectomies. The reference standard was living donor nephrectomies identified through the province’s tissue and organ procurement agency, with verification by manual chart review. Operating characteristics (sensitivity and PPV) of various algorithms using diagnostic, procedural, and physician billing codes were calculated.

Results:

During the study period, there were a total of 1199 living donor nephrectomies. Overall, the best algorithm for identifying living kidney donors was the presence of 1 diagnostic code for kidney donor (ICD-10 Z52.4) and 1 procedural code for kidney procurement/excision (1PC58, 1PC89, 1PC91). Compared with the reference standard, this algorithm had a sensitivity of 97% and a PPV of 90%. The diagnostic and procedural codes performed better than the physician billing codes (sensitivity 60%, PPV 78%).

Limitations:

The donor chart review and validation study was performed in Ontario and may not be generalizable to other regions.

Conclusions:

An algorithm consisting of 1 diagnostic and 1 procedural code can be reliably used to conduct health services research that requires the accurate determination of living kidney donors at the population level.

Quantifying Postdonation Risk of ESRD in Living Kidney Donors

Studies have estimated the average risk of postdonation ESRD for living kidney donors in the United States, but personalized estimation on the basis of donor characteristics remains unavailable. We studied 133,824 living kidney donors from 1987 to 2015, as reported to the Organ Procurement and Transplantation Network, with ESRD ascertainment via Centers for Medicare and Medicaid Services linkage, using Cox regression with late entries. Black race (hazard ratio [HR], 2.96; 95% confidence interval [95% CI], 2.25 to 3.89; P<0.001) and male sex (HR, 1.88; 95% CI, 1.50 to 2.35; P<0.001) was associated with higher risk of ESRD in donors. Among nonblack donors, older age was associated with greater risk (HR per 10 years, 1.40; 95% CI, 1.23 to 1.59; P<0.001). Among black donors, older age was not significantly associated with risk (HR, 0.88; 95% CI, 0.72 to 1.09; P=0.3). Greater body mass index was associated with higher risk (HR per 5 kg/m2, 1.61; 95% CI, 1.29 to 2.00; P<0.001). Donors who had a first-degree biological relationship to the recipient had increased risk (HR, 1.70; 95% CI, 1.24 to 2.34; P<0.01). C-statistic of the model was 0.71. Predicted 20-year risk of ESRD for the median donor was only 34 cases per 10,000 donors, but 1% of donors had predicted risk exceeding 256 cases per 10,000 donors. Risk estimation is critical for appropriate informed consent and varies substantially across living kidney donors. Greater permissiveness may be warranted in older black candidate donors; young black candidates should be evaluated carefully.

Increasing Use of the Expanded Criteria for Living Kidney Donation and Good Outcomes of Living Kidney Donors in Korea

BACKGROUND

Donor shortage for kidney transplantation may increase the number of expanded-criteria living donors (ECLDs). We investigated recent trends for ECLD use and the long-term outcomes of living kidney donors.

METHODS

We retrospectively analyzed medical records of 1,144 living kidney donors who donated at the Seoul National University Hospital from 1993 to 2015. The expanded criteria for living donation allow the following: age ≥60 years, body mass index >30 kg/m², history of hypertension, estimated glomerular filtration rate <80 mL/min, proteinuria or microscopic hematuria, and fasting glucose >100 mg/dL.

RESULTS

The mean age of donors was 40.7 ± 10.8 years, and there were 600 women (52.4%). A total of 466 donors (40.7%) met the ECLD criteria, and the proportion of ECLDs increased over time. Only 5 donors died after donation over a median follow-up of 7 years. No donor developed end-stage renal disease (ESRD). A urine protein-creatinine ratio ≥0.3 g/gCr was found in 14 patients and was more common in the ECLDs than in the standard-criteria living donors. The follow-up loss rate of donors was 59.3% at 5 years.

CONCLUSIONS

Both mortality and ESRD were very rare in carefully selected living kidney donors. However, living donors should be followed more carefully, because the follow-up loss rate was very high and ECLDs are increasingly used.

Long-Term Donor Outcomes after Pure Laparoscopic versus Open Living Donor Nephrectomy: Focus on Pregnancy Rates, Hypertension and Quality of Life

INTRODUCTION

The aim of the present study was to compare long-term donor outcomes after open and laparoscopic living donor nephrectomy. The focus was on pregnancy rates, hypertension and quality of life parameters.

MATERIALS AND METHODS

Data were retrospectively collected using our institution's electronic database and a structured questionnaire. The study included 30 donors after open donor nephrectomy (ODN) and 131 donors after laparoscopic donor nephrectomy (LDN).

RESULTS

Demographic data did not differ between groups. When asked for their preference, significantly more donors in the LDN group would choose the same surgical approach again. The overall frequency of postoperative complications was significantly lower in the LDN group. The incidence of grade III complications was 2% after LDN and 10% after ODN (p = 0.79). Only 2 out of 15 female donors aged between 18 and 45 years delivered a healthy child after DN. On interview, only 4 out of 15 female donors declared the desire to have children after DN.

CONCLUSIONS

From the donor perspective, long-term outcomes after LDN are more favorable than after ODN. To ensure favorable functional outcomes, strict preoperative donor selection and diligent long-term donor follow-up are required.