The Association Between Macroscopic Arteriosclerosis of the Renal Artery, Microscopic Arteriosclerosis, Organ Discard, and Kidney Transplant Outcome

Effect of Donor Cigarette Smoking in Kidney Transplantation: Re-Evaluation of Long-Term Outcomes

Cigarette smoking is a common risk factor associated with negative long-term outcomes in kidney transplant recipients. However, whether donor smoking decreases graft longevity or negatively impacts recipient survival after kidney transplantation remains unknown. Therefore, this study aims to investigate the long-term outcome in patients who received a kidney graft from a deceased smoking or non-smoking donor. A total of 580 patients were divided into two groups: patients who received a graft from a smoking donor (n = 276) and those who received a graft from a non-smoking donor (n = 304). Analysis of demographic factors showed that the non-smoking cohort was older, had more extended criteria donors and longer warm ischemia times. The primary composite endpoint of patient and graft survival was better in the smoking donor cohort when analyzed using Kaplan-Meier method but not when controlled for covariates in multivariate analyses. These findings do not support a previously reported negative impact of deceased donor smoking on kidney transplant recipients. Thus, the underlying results should not be interpreted in favor of a positive donor smoking history, but rather remind the transplant community that donor smoking should not be considered as a deciding factor in refusing an otherwise acceptable kidney graft.

The Independent Effects of Kidney Length and Vascular Plaque on Ten-Year Outcomes of Extended Criteria Donor Kidney Transplants

The independent effects of deceased donor kidney length and vascular plaque on long-term graft survival are not established. Utilizing DonorNet attachments from 4,480 expanded criteria donors (ECD) recovered between 2008 and 2012 in the United States with at least one kidney biopsied and transplanted, we analyzed the relationship between kidney length and vascular plaques and 10-year hazard of all-cause graft failure (ACGF) using causal inference methods in a Cox regression framework. The composite plaque score (range 0-4) and the presence of any plaque (yes, no) was also analyzed. Kidney length was modeled both categorically (<10, 10-12, >12 cm) as well as numerically, using a restricted cubic spline to capture nonlinearity. Effects of a novel composite plaque score 4 vs. 0 (HR 1.08; 95% CI: 0.96, 1.23) and the presence of any vascular plaque (HR 1.08; 95% CI: 0.98, 1.20) were attenuated after adjustment. Likewise, we identified a potential nonlinear relationship between kidney length and the 10-year hazard of ACGF, however the strength of the relationship was attenuated after adjusting for other donor factors. The independent effects of vascular plaque and kidney length on long-term ECD graft survival were found to be minimal and should not play a significant role in utilization.

Kidney utilization in the Netherlands - do we optimally use our donor organs?

BACKGROUND

To ensure optimal utilization of deceased donor kidneys, it is important to understand the precise reasons why kidneys are discarded. In this study we aimed to obtain a comprehensive overview of kidney utilization and discard during the entire donation process in the Netherlands.

METHODS

In this retrospective cohort study we analysed kidney utilization of 3856 kidneys in the Netherlands between 1 January 2015 and 31 December 2020. For every kidney that was not transplanted, we determined the moment of and reason for discard through a unique case-by-case assessment.

RESULTS

Kidney discard according to the traditional definition (procured but not transplanted) was 7.8%. However, when kidneys that seemed medically suitable at the beginning of the donation process were also included, many more potential donor kidneys were lost and the total non-utilization was 24.4%. Subjectively presumed impaired organ quality was responsible for 34.2% of all discarded kidneys. Two-thirds of kidneys discarded due to acute kidney injury (AKI) had only AKI stage 1 or 2.

CONCLUSION

The classical definition of organ discard underestimates the non-utilization of deceased donor kidneys. Strategies to improve kidney utilization could be a revision of the maximum allowed agonal time in donation after circulatory death, careful consideration in reporting and accepting kidneys from donors with AKI and a prospectively filled registry of detailed organ discard reasons, including the 'silent' non-utilization before procurement.

Impact of the explanting surgeon's impression of donor arteriosclerosis on outcome of kidney transplantations from donors aged ≥65 years

PURPOSE

Careful donor selection is important for kidney transplantations (KT) from suboptimal donors aged ≥65 years. Several tools such as histopathological assessment of preimplant biopsies have been shown to predict allograft survival and can be applied for selection. Whether the explanting surgeon's appraisal is associated with outcomes of KTs from suboptimal donors is unknown.

METHODS

We compared outcomes of KTs from ≥65-year-old deceased donors performed at our centre between 1999 and 2018 for which grading of macroscopic 'donor arteriosclerosis' (n=104) and 'organ quality' (n=208) as judged by the explanting surgeon and documented on the Eurotransplant kidney organ report was available.

RESULTS

No association was observed between degree of macroscopic donor arteriosclerosis and death-censored graft survival in univariable or multivariable regression analyses. Compared to KTs from donors with no/mild arteriosclerosis, KTs from donors with moderate/severe arteriosclerosis were associated with a significantly impaired allograft function 3 months, 1 year and 3 years after transplantation (e.g. at 3 years: 176.8 µmol/l vs 137.0 µmol/l, P=0.003). Following multivariable regression analysis, these differences remained significant at 3 months and 3 years after KT. No association was observed between degree of macroscopic arteriosclerosis and mortality or primary non-function as well as no consistent association with delayed graft function and histological arteriosclerosis. Assessment of 'organ quality' was not associated with outcomes.

CONCLUSION

Our data suggest that the explanting surgeon's assessment of donor arteriosclerosis is associated with allograft function. Larger studies and better standardization of kidney inspection after explantation are required to further explore the impact of surgeon's appraisal in KT.

Patient and Graft Survival After Dual Kidney Transplantation With Marginal Donors in Comparison to Matched Control Groups

BACKGROUND

Postmortal organ donor rates remain low in Germany, whereas donor age has been increasing considerably in the last decades. As a consequence of low donation rates older and more marginal donor kidneys are accepted for transplantation. However, procured kidneys from very old a/o marginal donors may be considered as not suitable for transplantation as a single organ and subsequently be discarded. However, dual transplantation of both kidneys from such donors may provide an opportunity to nevertheless use these organs for renal transplantation, thereby providing the twofold nephron mass as a single kidney transplantation.

METHODS

We compared in this retrospective analysis the outcome of 10 recipients of a dual kidney transplantation (DKT) with 40 matched recipients of a single kidney transplantation (SKT). Recipients were matched for donor and recipient age (ie, a maximum age difference of ±10 years in a ratio of 1:4 for DKT vs SKT recipients). In addition, a second SKT control group of 10 SKT recipients being transplanted immediately before each DKT recipient with a kidney from a donor aged ≥65 years was used for comparison. All renal transplant recipients were observed for up to 3 years or until July 31, 2020.

RESULTS

Mean donor and recipient age was 77.2 ± 4.6/75.1 ± 6.6/82.1 ± 7.9 and 66.4 ± 5.8/66.1 ± 6.0/64.8 ± 8.4 for SKT group 1/SKT group 2/DKT, respectively. Procurement serum creatinine concentrations were significantly higher in the DKT group in comparison to the SKT control group 1 (P = .019) as was the rate of transplant artery atherosclerosis (P = .021). Furthermore, Kidney Donor Profile Index, and Kidney Donor Risk Index were significantly higher (P = .0138/P = .064, and P < .001/P = .038) in the DKT group than in SKT group 1 and 2. Rates of acute rejection and delayed graft function were not significantly different between groups, though biopsy-proven acute rejection was numerically higher in the SKT groups. Patient survival and overall and death-censored graft survival rates were also not significantly different between groups, although they tended to be higher after DKT.

CONCLUSIONS

DKT provides an opportunity to successfully use postmortal kidneys even from donors aged >80 years and a Kidney Donor Profile Index ≥95% for renal transplantation. DKT may thereby increase the available pool of donors to better serve patients with end-stage renal disease on the waiting list.