Risk of kidney stones with surgical intervention in living kidney donors

Risk of new onset hyperuricemia and chronic kidney disease after living kidney donation through propensity score matching analysis

Living kidney donors have been regarded as those people having earned the healthiest status level after having undergone scrutiny. Although one's post-donation GFR is expected to fall to 50% of their pre-donation value, it is well documented that there is a compensatory increase in GFR which subsequently reaches approximately 60-70% of the donor's pre-donation value. Data regarding gout/hyperuricemia in living kidney donors has remained scarce until now. This study involved kidney donors enrolled within the years 2000 to 2017, where those who were selected to be matched to those in group of case cohort by age, year of index date, gender and co-morbidity were considered as the control cohort. During the 17-year study period 2,716 participants were enrolled. Results revealed that kidney donors experienced a risk of new onset gout/ hyperuricemia (adjusted HR = 1.73; 95%CI = 1.27, 2.36), and new onset CKD (adjusted HR = 6.7; 95% CI = 4.4, 10.21) were found to be higher in kidney donors. Our findings suggest that people after kidney donation are significantly associated with a higher risk of new onset gout/hyperuricemia. Clinical professionals therefore need to be cautious of new onset gouy/hyperuricemia after donation surgery.

One size does not fit all: understanding individual living kidney donor risk

Living donor kidney transplantation is the optimal treatment for end-stage kidney disease (ESKD) but confers a risk upon the donor, both in the short term and many years after donation. While perioperative mortality is low and longevity does not appear to be adversely affected, there are small increases in the risk of other important morbidities. The overall risk of ESKD among donors is low but appears to be three- to five-fold higher than among healthy non-donors, and this relative risk is even higher among donors of African ancestry. For these individuals, apolipoprotein L1 genotyping may be helpful. Kidney donors also have an increased risk of developing hypertension post-donation and a modestly increased risk of developing gout. Living kidney donation also increases the risk of gestational hypertension and preeclampsia while not affecting other important pregnancy outcomes. As our understanding of donor risk grows, it is important to counsel prospective donors according to their individual risk and so obtain better informed donor consent. As knowledge advances, it is also important that all clinicians who manage kidney transplant candidates have an up to date understanding of donor risk to inform shared decision making.

Outcomes of kidney donors with pre- and post-donation kidney stones

Roughly 25% of US transplant centers exclude donor candidates with kidney stones fearing future obstructive consequences and the possible association between stones and CKD. We compared the development of hypertension, proteinuria, and reduced eGFR in 227 kidney donors with kidney stones to 908 propensity score-matched donor controls without kidney stones using data from The Renal and Lung Donor Evaluation (RELIVE) Study which studied intermediate and long-term outcomes of 8922 donors who donated between 1963 and 2007. 200 donors had kidney stones prior to donation, 21 had post-donation stones, and 6 had pre- and post-donation stones. Donors with stones were older, more likely to be Caucasian, less likely to be related to the recipient and had a higher fasting glucose. After 16.5 ± 10.9 years (range 0-44 years) from donation to study close, no ESKD occurred in donors with stones. The multivariable risks of hypertension, proteinuria, and reduced GFR were similar in donors with and without kidney stones. We could not demonstrate an association between stones and adverse renal outcomes in kidney donors, and the occurrence of post-donation stones was distinctly rare. These data may provide a rationale for possibly a wider acceptance of donor candidates with low kidney stones burden.

Canadian Society of Transplantation and Canadian Society of Nephrology Commentary on the 2017 KDIGO Clinical Practice Guideline on the Evaluation and Care of Living Kidney Donors

Purpose of review:

To review an international guideline on the evaluation and care of living kidney donors and provide a commentary on the applicability of the recommendations to the Canadian donor population.

Sources of information:

We reviewed the 2017 Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline on the Evaluation and Care of Living Kidney Donors and compared this guideline to the Canadian 2014 Kidney Paired Donation (KPD) Protocol for Participating Donors.

Methods:

A working group was formed consisting of members from the Canadian Society of Transplantation and the Canadian Society of Nephrology. Members were selected to have representation from across Canada and in various subspecialties related to living kidney donation, including nephrology, surgery, transplantation, pediatrics, and ethics.

Key findings:

Many of the KDIGO Guideline recommendations align with the KPD Protocol recommendations. Canadian researchers have contributed to much of the evidence on donor evaluation and outcomes used to support the KDIGO Guideline recommendations.

Limitations:

Certain outcomes and risk assessment tools have yet to be validated in the Canadian donor population.

Implications:

Living kidney donors should be counseled on the risks of postdonation outcomes given recent evidence, understanding the limitations of the literature with respect to its generalizability to the Canadian donor population.

Long term follow up of kidney donors with asymptomatic renal stones

Patients with asymptomatic kidney stones have a high rate of progression to becoming symptomatic kidney stones when followed for several years. Small kidney stones are often found incidentally on imaging when evaluating patients for kidney donation, and there is a concern that after nephrectomy, the donor may become symptomatic and incur damage to the remaining kidney. We reviewed kidney donors at our institution with asymptomatic stones and surveyed them several years after donation to see if the stones became clinically active.

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.

Long-term risks of kidney living donation: review and position paper by the ERA-EDTA DESCARTES working group

Two recent matched cohort studies from the USA and Norway published in 2014 have raised some concerns related to the long-term safety of kidney living donation. Further studies on the long-term risks of living donation have since been published. In this position paper, Developing Education Science and Care for Renal Transplantation in European States (DESCARTES) board members critically review the literature in an effort to summarize the current knowledge concerning long-term risks of kidney living donation to help physicians for decision-making purposes and for providing information to the prospective live donors. Long-term risk of end-stage renal disease (ESRD) can be partially foreseen by trying to identify donors at risk of developing ‘de novo’ kidney diseases during life post-donation and by predicting lifetime ESRD risk. However, lifetime risk may be difficult to assess in young donors, especially in those having first-degree relatives with ESRD. The study from Norway also found an increased risk of death after living donor nephrectomy, which became visible only after >15 years of post-donation follow-up. However, these findings are likely to be largely the result of an overestimation due to the confounding effect related to a family history of renal disease. DESCARTES board members emphasize the importance of optimal risk–benefit assessment and proper information to the prospective donor, which should also include recommendations on health-promoting behaviour post-donation.

Venous Thromboembolism and the Risk of Death and Graft Loss in Kidney Transplant Recipients

BACKGROUND

The implications of venous thromboembolism (VTE) for morbidity and mortality in kidney transplant recipients are not well described.

METHODS

We conducted a retrospective study using linked healthcare databases in Ontario, Canada to determine the risk and complications of VTE in kidney transplant recipients from 2003 to 2013. We compared the incidence rate of VTE in recipients (n = 4,343) and a matched (1:4) sample of the general population (n = 17,372). For recipients with evidence of a VTE posttransplant, we compared adverse clinical outcomes (death, graft loss) to matched (1:2) recipients without evidence of a VTE posttransplant.

RESULTS

During a median follow-up of 5.2 years, 388 (8.9%) recipients developed a VTE compared to 254 (1.5%) in the matched general population (16.3 vs. 2.4 events per 1,000 person-years; hazard ratio [HR] 7.1, 95% CI 6.0-8.4; p < 0.0001). Recipients who experienced a posttransplant VTE had a higher risk of death (28.5 vs. 11.2%; HR 4.1, 95% CI 2.9-5.8; p < 0.0001) and death-censored graft loss (13.1 vs. 7.5%; HR 2.3, 95% CI 1.4-3.6; p = 0.0006) compared to matched recipients who did not experience a posttransplant VTE.

CONCLUSIONS

Kidney transplant recipients have a sevenfold higher risk of VTE compared to the general population with VTE conferring an increased risk of death and graft loss.

KDIGO Clinical Practice Guideline on the Evaluation and Care of Living Kidney Donors

The 2017 Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline on the Evaluation and Care of Living Kidney Donors is intended to assist medical professionals who evaluate living kidney donor candidates and provide care before, during and after donation. The guideline development process followed the Grades of Recommendation Assessment, Development, and Evaluation (GRADE) approach and guideline recommendations are based on systematic reviews of relevant studies that included critical appraisal of the quality of the evidence and the strength of recommendations. However, many recommendations, for which there was no evidence or no systematic search for evidence was undertaken by the Evidence Review Team, were issued as ungraded expert opinion recommendations. The guideline work group concluded that a comprehensive approach to risk assessment should replace decisions based on assessments of single risk factors in isolation. Original data analyses were undertaken to produce a "proof-in-concept" risk-prediction model for kidney failure to support a framework for quantitative risk assessment in the donor candidate evaluation and defensible shared decision making. This framework is grounded in the simultaneous consideration of each candidate's profile of demographic and health characteristics. The processes and framework for the donor candidate evaluation are presented, along with recommendations for optimal care before, during, and after donation. Limitations of the evidence are discussed, especially regarding the lack of definitive prospective studies and clinical outcome trials. Suggestions for future research, including the need for continued refinement of long-term risk prediction and novel approaches to estimating donation-attributable risks, are also provided.In citing this document, the following format should be used: Kidney Disease: Improving Global Outcomes (KDIGO) Living Kidney Donor Work Group. KDIGO Clinical Practice Guideline on the Evaluation and Care of Living Kidney Donors. Transplantation. 2017;101(Suppl 8S):S1-S109.

Long-Term Non-End-Stage Renal Disease Risks After Living Kidney Donation

Despite generally positive outcomes and high rates of satisfaction, living kidney donors are at risk for both medical and psychosocial problems. In this review, the authors summarize non-end-stage renal disease (ESRD) risks for donors and describe limitations to the data. We review the evidence of medical risks (e.g. increased cardiovascular disease and mortality, preeclampsia) and psychosocial risks (e.g. mood disturbance, financial burden). We then discuss the evidence of differential risks among subsets and the impact of postdonation events (e.g. development of diabetes). Collectively, available evidence indicates the following. (1) Recognizing the importance of non-ESRD risks has been overshadowed by analyses of the reported risk of ESRD. This imbalance should be remedied. (2) There is little quantification of the true contribution of donation to medical and psychosocial outcomes. (3) Most studies, to date, have been retrospective, with limited sample sizes and diversity and with less-than-ideal controls for comparison of outcomes. (4) Many postdonation events (diabetes and hypertension) can now be reasonably predicted, and their association with adverse outcomes can be quantified. (5) Mechanisms and systems need to be implemented to evaluate and care for donors who develop medical and/or psychosocial problems. (6) Costs to donors are a significant burden, and making donation financially neutral should be a priority.

Outcomes of living kidney donors with medullary sponge kidney

BACKGROUND

Patients with medullary sponge kidney (MSK) commonly encounter recurrent nephrolithiasis. The existing knowledge on safety of donors with MSK has not been studied.

METHODS

We conducted a retrospective cohort study at a tertiary referral hospital to assess the outcomes of living kidney donors with MSK. All adults with MSK (N = 26) who underwent nephrectomy as living kidney donors between January 2000 and September 2014 were included. Non-donors with MSK (N = 78) were randomly selected by matching the year of birth and the comorbidity score with a ratio of 1:3 for comparison.

RESULTS

The incident rates of symptomatic stone were 0.7, 0.4 and 4.9 events/100 patient-years in donors, recipients and non-donors, respectively. After adjusting for history of kidney stones and baseline estimated glomerular filtration rate (eGFR), the kidney stone-related event was significantly lower in donors than in non-donors (hazard ratio 0.14; 95% confidence interval 0.01-0.66). One recipient of MSK living donor had symptomatic stone at median follow-up time of 8.4 years (interquartile range 5.6-12.4 years). None of MSK donors had hypercalciuria, hypocitraturia or hyperoxaluria prior to kidney donation. At 5 years after the index surgery date, there was no significant difference in eGFR between donors and non-donors (76.1 versus 70.9 mL/min/1.73 m², P = 0.12).

CONCLUSIONS

These findings are reassuring for the safety of MSK kidney donors with normal kidney function, low kidney stone risk and no significant comorbidity.

Gender differences in use of prescription narcotic medications among living kidney donors

Prescription narcotic use among living kidney donors is not well described. Using a unique database that integrates national registry identifiers for living kidney donors (1987-2007) in the United States with billing claims from a private health insurer (2000-2007), we identified pharmacy fills for prescription narcotic medications in periods 1-4 and >4 yr post-donation and estimated relative likelihoods of post-donation narcotic use by Cox regression. We also compared narcotic fill rates and medication possession ratios (MPRs, defined as (days of medication supplied)/(days observed)), between donors and age- and sex-matched non-donors. Overall, rates of narcotic medication fills were 32.3 and 32.4 per 100 person-years in periods 1-4 and >4 yr post-donation. After age and race adjustment, women were approximately twice as likely as men to fill a narcotic prescription in years 1-4 (adjusted hazard ratio, aHR, 2.28; 95% confidence interval, CI, 1.86-2.79) and >4 yr (aHR 1.70; 95% CI 1.50-1.93). MPRs in donors were low (<2.5% days exposed), and lower than among age- and sex-matched non-donors. Prescription narcotic medication use is more common among women than men in the intermediate term after live kidney donation. Overall, total narcotic exposure is low, and lower than among non-donors from the general population.

End-stage renal disease risk in live kidney donors: what have we learned from two recent studies?

PURPOSE OF REVIEW

Living kidney donation improves the lives of those with kidney failure, but there are potential risks to the donor. We review two recent publications that describe the long-term risk of end-stage renal disease (ESRD) in living kidney donors.

RECENT FINDINGS

One study reported that the long-term risk (median follow-up 15.1 years) of ESRD was, in relative terms, 11-fold higher in living kidney donors compared to healthy nondonors, and suggested a hereditary association since all affected donors were biologically related to their recipients and the causes were predominantly immunological diseases. In a second study, we estimated that the long-term risk (median follow-up 7.6 years) of ESRD was, in relative terms, eight-fold higher in living kidney donors compared to healthy matched nondonors. In both studies, the absolute increase in the 15-year incidence of ESRD from donation was below 0.5%. There are limitations in these studies, which have raised questions about the accuracy of the estimates of risk.

SUMMARY

The results of these studies should be discussed with potential living kidney donors with an emphasis on the low 15-year incidence of ESRD following donation. The lifetime incidence of ESRD for donors of different age, race, and other characteristics requires further study.

Risk of major hemorrhage after kidney transplantation

BACKGROUND

Major hemorrhagic events are associated with significant morbidity and mortality. We examined the three-year cumulative incidence of hospitalization with major nontraumatic hemorrhage after kidney transplantation.

METHODS

We performed a retrospective cohort study using healthcare administrative data of all adult-incident kidney-only transplantation recipients in Ontario, Canada from 1994 to 2009. We calculated the three-year cumulative incidence, event rate, and incident rate ratio of hospitalization with major hemorrhage, its subtypes and those undergoing a hemorrhage-related procedure. RESULTS were stratified by patient age and donor type and compared to a random and propensity-score matched sample from the general population.

RESULTS

Among 4,958 kidney transplant recipients, the three-year cumulative incidence of hospitalization with nontraumatic major hemorrhage was 3.5% (95% confidence interval [CI] 3.0-4.1%, 12.7 events per 1,000 patient-years) compared to 0.4% (95% CI 0.4-0.5%) in the general population (RR = 8.2, 95% CI 6.9-9.7). The crude risk of hemorrhage was 3-9-fold higher in all subtypes (upper/lower gastrointestinal, intra-cranial) and 15-fold higher for gastrointestinal endoscopic procedures compared to the random sample from the general population. After propensity score matching, the relative risk for major hemorrhage and its subtypes attenuated but remained elevated. The cumulative incidence of hemorrhage was higher for older individuals and those with a deceased donor kidney.

CONCLUSION

Kidney transplantation recipients have a higher risk of hospitalization with hemorrhage compared to the general population, with about 1 in 30 recipients experiencing a major hemorrhage in the three years following transplant.

Gestational hypertension and preeclampsia in living kidney donors

BACKGROUND

Young women wishing to become living kidney donors frequently ask whether nephrectomy will affect their future pregnancies.

METHODS

We conducted a retrospective cohort study of living kidney donors involving 85 women (131 pregnancies after cohort entry) who were matched in a 1:6 ratio with 510 healthy nondonors from the general population (788 pregnancies after cohort entry). Kidney donations occurred between 1992 and 2009 in Ontario, Canada, with follow-up through linked health care databases until March 2013. Donors and nondonors were matched with respect to age, year of cohort entry, residency (urban or rural), income, number of pregnancies before cohort entry, and the time to the first pregnancy after cohort entry. The primary outcome was a hospital diagnosis of gestational hypertension or preeclampsia. Secondary outcomes were each component of the primary outcome examined separately and other maternal and fetal outcomes.

RESULTS

Gestational hypertension or preeclampsia was more common among living kidney donors than among nondonors (occurring in 15 of 131 pregnancies [11%] vs. 38 of 788 pregnancies [5%]; odds ratio for donors, 2.4; 95% confidence interval, 1.2 to 5.0; P=0.01). Each component of the primary outcome was also more common among donors (odds ratio, 2.5 for gestational hypertension and 2.4 for preeclampsia). There were no significant differences between donors and nondonors with respect to rates of preterm birth (8% and 7%, respectively) or low birth weight (6% and 4%, respectively). There were no reports of maternal death, stillbirth, or neonatal death among the donors. Most women had uncomplicated pregnancies after donation.

CONCLUSIONS

Gestational hypertension or preeclampsia was more likely to be diagnosed in kidney donors than in matched nondonors with similar indicators of baseline health. (Funded by the Canadian Institutes of Health Research and others.).