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. 1. Introduction Delayed graft function (DGF) complicates the early posttransplant period following kidney transplants (KTxs) in approximately 30% of deceased donors and less than 5% of living donor KTx recipients and confers an increased risk of superimposed acute rejection [1–3]. DGF is associated with significantly inferior long-term outcomes in KTx recipients and the outcomes are further worsened when rejection is superimposed on DGF [1–3]. Thus, timely diagnosis and treatment of rejection occurring during DGF are critical. However, noninvasive diagnosis of rejection during DGF is difficult and allograft biopsy is the only reliable test to diagnose it. Therefore, performance of weekly biopsies until DGF resolves is a common practice [4]. Currently, induction therapy using rabbit antithymocyte globulin/Thymoglobulin (ATG) (or, less commonly, Basiliximab/Simulect) is used almost universally during DGF together with potent maintenance immunosuppression (calcineurin-inhibitor + mycophenolate ± corticosteroid). The incidence of rejection during DGF and the continued need for