Three-month protocol biopsies do not detect subclinical rejection in pediatric kidney transplant recipients at a single center

Background Subacute allograft rejection (SAR) results in chronic allograft nephropathy and decreased allograft survival. Protocol biopsies (PB) are performed in many top centers to identify SAR. Our study aimed to evaluate the rate of SAR detected in PB at our single center. Methods Retrospective review of 38 pediatric patients (pts) who received a kidney allograft from April 2014 through January 2018. Induction immunosuppression consisted of basiliximab (n = 25). High risk pts received antithymocyte globulin (n = 13). Tacrolimus-based triple drug maintenance immunosuppression was used. PBs were performed 3–6 months after transplant. Pathology was evaluated by trained pathologists and classified using Banff criteria. Results Thirty-eight pts were included. Five pts underwent biopsy before 3 months due to elevated creatinine or BK viremia. Thirty-three pts underwent PB 12–23 weeks after transplant. Six pts had elevated creatinine at the time of PB; only 1/6 biopsies showed acute rejection. Of the remaining 27 PBs, only 1/27 showed acute rejection. The total rejection rate at 6 months post-transplant was 5.26%, with a SAR rate of 3.7%. Conclusions These findings do not substantiate early PB at our institution. Our study suggests that perhaps later time points for PB when immunosuppressive meds are at their lowest levels or use of novel biomarkers as an initial screen for biopsy in patients at risk for SAR would be more informative.