Early Allograft Biopsies Performed During Delayed Graft Function May Not Be Necessary Under Thymoglobulin Induction

Histopathological Features and Role of Allograft Kidney Biopsy Among Recipients With Prolonged Delayed Graft Function: A Review

Delayed graft function (DGF) is an early posttransplant complication predictive of adverse outcomes. This "acute kidney injury of transplantation" is often defined as allograft dysfunction requiring renal replacement within 7 d posttransplantation. DGF is an important area of study because it is emerging with efforts to expand the donor pool and address the supply-demand gap in kidney transplantation. DGF is often caused by severe kidney injury mechanisms because of multiple donors, recipients, and immunologic factors. The role of kidney biopsy, particularly in prolonged DGF, is an ongoing area of research and inquiry for clinicians and researchers alike to better define, manage, and predict outcomes of this early posttransplant event. This review aims to provide an in-depth, comprehensive summary of the literature to date on the histopathology of DGF and the role of kidney transplant biopsies in prolonged DGF.

Prolonged warm ischemia time leads to severe renal dysfunction of donation-after-cardiac death kidney grafts

Kidney transplantation with grafts procured after donation-after-cardiac death (DCD) has led to an increase in incidence of delayed graft function (DGF). It is thought that the warm ischemic (WI) insult encountered during DCD procurement is the cause of this finding, although few studies have been designed to definitely demonstrate this causation in a transplantation setting. Here, we use a large animal renal transplantation model to study the effects of prolonged WI during procurement on post-transplantation renal function. Kidneys from 30 kg-Yorkshire pigs were procured following increasing WI times of 0 min (Heart-Beating Donor), 30 min, 60 min, 90 min, and 120 min (n = 3-6 per group) to mimic DCD. Following 8 h of static cold storage and autotransplantation, animals were followed for 7-days. Significant renal dysfunction (SRD), resembling clinical DGF, was defined as the development of oliguria < 500 mL in 24 h from POD3-4 along with POD4 serum potassium > 6.0 mmol/L. Increasing WI times resulted in incremental elevation of post-operative serum creatinine that peaked later. DCD120min grafts had the highest and latest elevation of serum creatinine compared to all groups (POD5: 19.0 ± 1.1 mg/dL, p < 0.05). All surviving animals in this group had POD4 24 h urine output < 500 cc (mean 235 ± 172 mL) and elevated serum potassium (7.2 ± 1.1 mmol/L). Only animals in the DCD120min group fulfilled our criteria of SRD (p = 0.003), and their renal function improved by POD7 with 24 h urine output > 500 mL and POD7 serum potassium < 6.0 mmol/L distinguishing this state from primary non-function. In a transplantation survival model, this work demonstrates that prolonging WI time similar to that which occurs in DCD conditions contributes to the development of SRD that resembles clinical DGF.

Utility and safety of early allograft biopsy in adult deceased donor kidney transplant recipients

INTRODUCTION

Delayed graft function (DGF) is considered a risk factor for rejection after kidney transplantation (KTx). Clinical guidelines recommend weekly allograft biopsy until DGF resolves. However, who may benefit the most from such an aggressive policy and when histology should be evaluated remain debated.

METHODS

We analyzed 223 biopsies in 145 deceased donor KTx treated with basiliximab or anti-thymocyte globulin (rATG) and calcineurin inhibitor-based maintenance. The aim of the study was to assess the utility and safety of biopsies performed within 28 days of transplant. Relationships between transplant characteristics, indication, timing, and biopsy-related outcomes were evaluated.

RESULTS

Main indication for biopsy was DGF (87.8%) followed by lack of improvement in graft function (9.2%), and worsening graft function (3.1%). Acute tubular necrosis was the leading diagnosis (89.8%) whereas rejection was detected in 8.2% specimens. Rejection was more frequent in patients biopsied due to worsening graft function or lack of improvement in graft function than DGF (66.7% vs. 3.5%; P = 0.0075 and 33.3% vs. 3.5%; P = 0.0104, respectively) and in biopsies performed between day 15 and 28 than from day 0 to 14 (31.2% vs. 3.7%; P = 0.0002). Complication rate was 4.1%. Management was affected by the information gained with histology in 12.2% cases (7% considering DGF).

CONCLUSIONS

In low-immunological risk recipients treated with induction and calcineurin inhibitors maintenance, protocol biopsies obtained within 2 weeks of surgery to rule out rejection during DGF do not necessarily offer a favourable balance between risks and benefits. In these patients, a tailored approach may minimize complications thus optimizing results.

Alemtuzumab Induction Is Associated With Equalization of Graft Outcomes Between Elderly and Nonelderly Kidney Transplant Recipients: A Single-Center Report

OBJECTIVES

Alemtuzumab (monoclonal anti-CD52 antibody) provides profound lymphocyte depletion and offers numerous advantages as an induction agent. Elderly recipients (> 65 years old) traditionally have inferior posttransplant outcomes versus younger recipients. We investigated short-term and long-term patient and graft survival rates following alemtuzumab induction in elderly recipients.

MATERIALS AND METHODS

This retrospective analysis, which included 676 renal allograft transplant recipients with alemtuzumab induction, was conducted at the University of Toledo Medical Center between March 2006 and November 2015. We used 2-sided t test, Pearson chi-square test, Fisher exact test, and Cox proportional hazard regressions with 95% confidence interval for analyses. P < .05 was significant.

RESULTS

Elderly recipients were more likely to receive a kidney from an inferior donor (deceased donor: 82% vs 72.4%; P = .030) and have higher mean kidney donor profile index (46.2 vs 38.4; P = .024) than nonelderly recipients. Elderly recipients were more likely to experience delayed graft function (15.1% vs 8.5%; P = .038). Elderly recipients demonstrated death-censored graft survival (1 year: 95.4% vs 93.1%; 3 years: 88.5% vs 93.3%; 5 years: 83.1% vs 86.4%) and rejection rates (1 year: 19.8% vs 21.2%; 3 years: 22.1% vs 25.3%; 5 years: 23.8% vs 26.9%) similar to nonelderly recipients. Elderly recipients had significantly higher overall mortality rates than recipients under 65 years old (29.8% vs. 13.2%; P = .001). Although 1-year patient survival was similar to younger recipients (94.8% vs 96.3%; P = .431), 3-year (80.0% vs 91.5%; P = .006) and 5-year (72.9% vs 86.2%; P = .19) rates were significantly decreased in elderly recipients.

CONCLUSIONS

Elderly age is not a predictor of rejection or death-censored graft loss in individuals who receive alemtuzumab induction. Despite elevated overall mortality, elderly recipients induced with alemtuzumab demonstrated rejection, graft, and short-term patient survival rates similar to younger recipients.

The Utility of Serial Allograft Biopsies during Delayed Graft Function in Renal Transplantation under Current Immunosuppressive Regimens

Delayed graft function (DGF) of kidney transplants increases risk of rejection. We aimed to assess the utility of weekly biopsies during DGF in the setting of currently used immunosuppression and identify variables associated with rejection during DGF. We reviewed all kidney transplants at our institution between January 2008 and December 2011. All patients received rabbit antithymocyte globulin/Thymoglobulin (ATG) or Basiliximab/Simulect induction with maintenance tacrolimus + mycophenolate + corticosteroid therapy. Patients undergoing at least one weekly biopsy during DGF comprised the study group. Eighty-three/420 (19.8%) recipients during this period experienced DGF lasting ≥1 week and underwent weekly biopsies until DGF resolved. Biopsy revealed significant rejection only in 4/83 patients (4.8%) (one Banff 1-A and two Banff 2-A cellular rejections, and one acute humoral rejection). Six other/83 patients (7.2%) had Banff-borderline rejection of uncertain clinical significance. Four variables (ATG versus Basiliximab induction, patient age, panel reactive anti-HLA antibody level at transplantation, and living versus deceased donor transplants) were statistically significantly different between patients with and without rejection, though the clinical significance of these differences is questionable given the low incidence of rejection. Conclusions. Under current immunosuppression regimens, rejection during DGF is uncommon and the utility of serial biopsies during DGF is limited.

Immediate postoperative sonography of renal transplants: vascular findings and outcomes

OBJECTIVE

The purpose of this study was to determine the frequency and types of significant vascular findings on bedside sonography immediately after renal transplantation and which abnormalities would suggest a benefit from early surgical revision.

MATERIALS AND METHODS

Five hundred seventy-five renal transplant sonograms obtained within 4 hours of surgery were retrospectively reviewed for major vascular abnormalities: lack of renal artery (RA) or renal vein (RV) flow, elevated peak systolic velocity (PSV)>300 cm/s, parvus tardus waveforms, and markedly decreased or no color parenchymal flow. Clinical outcomes of abnormal cases were reviewed, including reoperations and percutaneous interventions.

RESULTS

Thirty-two (5.6%) patients underwent repeat surgery within the first week, 16 for nonvascular causes. Forty-seven (8.2%) patients had positive sonography findings. In 16 patients, sonography impacted the decision for reoperation, with 14 confirmed vascular diagnoses: compartment syndrome (n=7), RV thrombosis (n=3), RA thrombosis (n=1), RA and RV thromboses (n=2), and vascular steal (n=1). All were salvaged except the three RV thromboses. Two patients had no vascular abnormality at surgery. All 16 had markedly decreased color flow and varying abnormalities of PSV and waveforms. Outcomes of the remaining 31 cases were infarct (n=1), renal or iliac artery stenoses eventually requiring stents (n=4), and normalized (n=26). These 26 had elevated PSV with normal or near-normal color flow. Unpaired Student t tests showed no significant difference in PSV between patients requiring surgery or stents and those who normalized (p=0.34).

CONCLUSION

Immediate postoperative sonography has a spectrum of vascular findings, of which markedly decreased color flow is most likely to benefit from immediate reoperation.