Impact of Early Low-Grade Proteinuria and Allograft Dysfunction on Survival in Expanded Criteria Donor Kidney Transplant Recipients

Donor Proteinuria and Allograft Function in Kidney Transplantation: Short- and Long-Term Results From a Retrospective Cohort Study

Donor proteinuria (DP) is a common but rarely evaluated aspect of today's kidney transplant allocation process. While proteinuria after kidney transplantation is a risk factor for impaired graft function and survival, the long-term effects of DP in kidney transplantation have not yet been evaluated. Therefore, this study aims to investigate the impact of DP on the long-term outcome after kidney transplantation. A total of 587 patients were found to be eligible and were stratified into two groups: (1) those receiving a graft from a donor without proteinuria (DP-) and (2) those receiving a graft from a donor with proteinuria (DP+). At 36 months, there was no difference in the primary composite endpoint including graft loss and patient survival (log-rank test, p = 0.377). However, the analysis of DP+ subgroups showed a significant decrease in overall patient survival in the group with high DP (p = 0.017). DP did not adversely affect patient or graft survival over 36 months. Nevertheless, this work revealed a trend towards decreased overall survival of patients with severe proteinuria in the subgroup analysis. Therefore, the underlying results suggest caution in allocating kidneys from donors with high levels of proteinuria.

Donor Klotho KL-VS Polymorphism Predicts Allograft Glomerulosclerosis and Early Post-Transplant Kidney Function

BACKGROUND

The Klotho protein, encoded by the KL (Klotho) gene, exerts antiaging and antifibrotic effects. The KL-VS genotype diminishes Klotho expression and correlates with cardiovascular death, heart failure, and chronic kidney disease progression. The aim of this study was to analyze the contribution of donor Klotho rs9536314 and rs9527025 polymorphisms (KL-VS genotype) to renal allograft morphology and function in the early post-transplant period.

METHODS

Clinical data and biopsy reports of 170 deceased donor transplantations were retrieved from standard medical files. Donor DNA was genotyped for rs9527025 and rs9536314 SNPs using custom TaqMan assays.

RESULTS

As rs9527025 remained in full linkage with rs9536314, we report results for the latter. The analyses were performed for G dominant model (GG+GT vs TT). We found an association between reported SNP alleles, morphologic changes in the peritransplant biopsy, and kidney function 3 months after engraftment. A chronic glomerulopathy score of >0 was found in 12.2% of GG+GT cases and in 3.2% of TT cases (P = .023). For G allele carriers, the third month's median estimated glomerular filtration rate value was 35.0 (range, 20.4-76.6 mL/min), while for TT haplotype, the value was 46.3 (range, 15.5-96.8 mL/min), P = .001. At the third post-transplant month, proteinuria incidence was higher for organs with G allele than with TT haplotype (24.4% vs 9.5%; P = .030; odds ratio 3.09; 95% confidence interval 1.22-7.69).

CONCLUSION

Deceased donor KL-VS polymorphism, altering protein dimerization and coreceptor function, predicts early renal transplant glomerular lesions and function. Further analyses for mentioned effect durability are necessary.

ETHICS STATEMENT

This study complies with the Helsinki Congress and the Istanbul Declaration regarding donor source. Donors were not prisoners, and were not paid or coerced.

Relationship between early proteinuria and long term outcome of kidney transplanted patients from different decades of donor age

Background

Proteinuria after kidney transplantation portends a worse graft survival. However the magnitude of proteinuria related to patient and graft survival and its correlation with donor and recipient characteristics are poorly explored.

Methods

This study investigated the impact of post transplant proteinuria in the first year in 1127 kidney transplants analyzing the impact of different donor ages. Proteinuria cut off was set at 0.5 g/day.

Results

Transplants with proteinuria > 0.5 g/day correlated with poor graft and patient outcome in all donor age groups. In addition, 6-month-1-year proteinuria increase was significantly associated with graft outcome, especially with donors > 60 years old (p <  0.05; Odd Ratio 1.8). 1-year graft function (eGFR < or ≥ 44 ml/min) had similar impact to proteinuria (≥ 0.5 g/day) on graft failure (Hazard Ratio 2.77 vs Hazard Ratio 2.46). Low-grade proteinuria (0.2–0.5 g/day) demonstrated a trend for worse graft survival with increasing donor age. Also in kidney-paired analysis proteinuria ≥0.5 effect was more significant with donors > 50 years old (Odd Ratio 2.3).

Conclusions

Post-transplant proteinuria was increasingly harmful with older donor age. Proteinuria ≥0.5 g/day correlates with worse outcomes in all transplanted patients. Prognostic value of proteinuria and eGFR for graft and patient survival was comparable and these two variables remain significant risk factors even in a multivariate model that take into consideration the most important clinical variables (donor age, rejection, delayed graft function and cytomegalovirus viremia among others).