Delayed graft function in pediatric deceased donor kidney transplantation: donor-related risk factors and impact on two-yr graft function and survival: a single-center analysis

Clinical indicators of slow graft function and outcome after pediatric kidney transplantation

BACKGROUND

Lesser degrees of perioperative ischemia-reperfusion injury that does not require dialysis may nonetheless influence allograft outcomes, necessitating evaluation of suitable surrogate indicators of perioperative allograft injury.

METHODS

This retrospective analysis of pediatric kidney transplants evaluated two indicators representing pace and completeness of recovery, for association with 12-month estimated glomerular filtration rate (eGFR) and first-year rate of eGFR decline: time to creatinine nadir (TTN) and ratio of recipient/donor unadjusted GFR (uGFR_R/D ) at 1-month post-transplant. Donor, recipient, and perioperative risk factors were tested further for association with these 2 indicators.

RESULTS

179 patients (190 transplants) aged 13 (IQR 7-17) years and 56% male were included. Twelve-month eGFR was strongly associated with unadjusted GFR at 1 month (uGFR_1M , p < .001) and uGFR_R/D (p = .003), but not with TTN. None of the indicators was associated with the rate of subsequent eGFR decline after 1-month post-transplant. As a potential surrogate indicator, uGFR_1M is effectively modeled by TTN and uGFR_R/D (adjusted R²  = 0.57) and is associated with 12-month eGFR (β = 0.81 ± 0.08; p < .001). Clinical factors associated with uGFR_R/D included donor uGFR (p < .001), BSA (p = .026), age (p = .074), and recipient BSA (p < .001). Factors associated with pace of recovery (TTN) included donor uGFR (p = .018), type (p = .019), and recipient BSA (p = .022).

CONCLUSIONS

The uGFR_R/D ratio, but not TTN, is a useful indicator of perioperative allograft damage that is associated with one-year functional outcome; and uGFR_1M is a potential early surrogate outcome. Donor, recipient, and perioperative factors that are associated with slow allograft function are identified.

Pediatric deceased donor kidney transplant outcomes under the Kidney Allocation System

The Kidney Allocation System (KAS) has resulted in fewer pediatric kidneys being allocated to pediatric deceased donor kidney transplant (pDDKT) recipients. This had prompted concerns that post-pDDKT outcomes may worsen. To study this, we used SRTR data to compare the outcomes of 953 pre-KAS pDDKT (age <18 years) recipients (December 4, 2012-December 3, 2014) with the outcomes of 934 post-KAS pDDKT recipients (December 4, 2014-December 3, 2016). We analyzed mortality and graft loss by using Cox regression, delayed graft function (DGF) by using logistic regression, and length of stay (LOS) by using negative binomial regression. Post-KAS recipients had longer pretransplant dialysis times (median 1.26 vs 1.07 years, P = .02) and were more often cPRA 100% (2.0% vs 0.1%, P = .001). Post-KAS recipients had less graft loss than pre-KAS recipients (hazard ratio [HR]: _0.35 0.54_0.83 , P = .005) but no statistically significant differences in mortality (HR: _0.29 0.72_1.83 , P = .5), DGF (odds ratio: _0.93 1.32_1.93 , P = .2), and LOS (LOS ratio: _0.96 1.06_1.19 , P = .4). After adjusting for donor-recipient characteristics, there were no statistically significant post-KAS differences in mortality (adjusted HR: _0.37 1.04_2.92 , P = .9), DGF (adjusted odds ratio: _0.94 1.41_2.13 , P = .1), or LOS (adjusted LOS ratio: _0.93 1.04_1.16 , P = .5). However, post-KAS pDDKT recipients still had less graft loss (adjusted HR: _0.38 0.59_0.91 , P = .02). KAS has had a mixed effect on short-term posttransplant outcomes for pDDKT recipients, although our results are limited by only 2 years of posttransplant follow-up.

Impact of the kidney allocation system on young pediatric recipients

The kidney allocation system (KAS) altered pediatric candidate prioritization. We determined KAS's impact on pediatric kidney recipients by examining delayed graft function (DGF) rates from 2010 to 2016. A propensity score-matched pediatric recipients pre- and post-KAS. A semiparametric decomposition analysis estimated the contributions of KAS-related changes in donor characteristics and dialysis time on DGF rate. The unadjusted odds of DGF were 69% higher post-KAS for young (<10 years at listing) recipients (N = 1153, P = .02) but were not significantly increased for older pediatric (10-17 years at listing) recipients (N = 2624, P = .48). Post-KAS, young recipients received significantly fewer pediatric (<18 years) donor kidneys (21% vs 32%, P < .01) and had longer median pretransplant dialysis time (603 vs 435 days, P < .01). After propensity score matching, post-KAS status increased the odds of DGF in young recipients 71% (OR 1.71, 95% CI 1.01-2.46). In decomposition analysis, 24% of the higher DGF rate post-KAS was attributable to donor characteristics and 19% to increased recipient dialysis time. In a confirmatory survival analysis, DGF was associated with a 2.2 times higher risk of graft failure (aHR2.28, 95% CI 1.46-3.54). In conclusion, KAS may lead to worse graft survival outcomes in children. Allocation changes should be considered.

Association Between Slow and Delayed Graft Function With Graft Outcomes in Pediatric and Adolescent Deceased Donor Kidney Transplant Recipients

BACKGROUND

Delayed graft function (DGF) is associated with an increased risk of graft loss in adult kidney transplant recipients but the association remains inconsistent in pediatric recipients. The aim of this study is to examine the association between DGF and graft loss in pediatric and adolescent deceased donor kidney transplant recipients aged 21 years or younger using Australia and New Zealand Dialysis and Transplant registry.

METHODS

The associations between DGF status, overall and death-censored graft loss (DCGL) were examined using adjusted Cox regression analyses.

RESULTS

There were 367 recipients followed up for a median of 9.7 years between 1990 and 2012, with 82 (22%) experiencing DGF requiring dialysis (DGF-D) in the first 72 hours after transplant. Compared with recipients who did not experienced DGF-D, the adjusted hazard ratios for overall graft loss and DCGL in recipients who have experienced DGF-D was 2.08 (95% confidence interval [95% CI], 1.39-3.11; P < 0.001) and 2.09 (95% CI, 1.38-3.17; P < 0.001), respectively, independent of era, age, and initial immunosuppression. Slow graft function, defined as no immediate function but not requiring dialysis, was associated with adjusted hazard ratios of 2.60 (95% CI, 1.50-4.51; P = 0.001) for overall graft loss and 2.49 (95% CI, 1.39-4.47; P = 0.002) for DCGL.

CONCLUSIONS

This study has shown that DGF, encompassing a spectrum of renal dysfunction after kidney transplantation including those who may or may not require dialysis, is an independent risk factor for long-term graft loss.

Delayed graft function and its management in children

Delayed graft function (DGF) is commonly defined as the requirement for dialysis within the first 7 days following renal transplantation. The major underlying mechanism is related to ischaemia/reperfusion injury, which includes microvascular inflammation and cell death and apoptosis, and to the regeneration processes. Several clinical factors related to donor, recipient and organ procurement/transplantation procedures may increase the risk of DGF, including donor cardiovascular instability, older donor age, donor creatinine concentration, long cold ischaemia time and marked body mass index of both the donor and recipient. Some of these parameters have been used in specific predictive formulas created to assess the risk of DGF. A variety of other pre-, intra- and post-transplant clinical factors may also increase the risk of DGF, such as potential drug nephrotoxicity, surgical problems and/or hyperimmunization of the recipient. DGF may decrease the long-term graft function, but data on this effect are inconsistent, partially due to the many different types of organ donation. Relevant management strategies may be classified into the classic clinical approach, which has the aim of minimizing the individual risk factors of DGF, and specific pharmacologic strategies, which are designed to prevent or treat ischaemia/reperfusion injury. Both strategies are currently being evaluated in clinical trials.