The Role of Protocol Allograft Biopsies in Postrenal Transplantation: A Systematic Review and Meta-analysis

Abstract

Introduction: Kidney transplantation is the preferred treatment for end-stage kidney disease, offering improved outcomes compared to dialysis. However, factors such as immunological rejection, drug toxicity, and infections limit its success. Incorporating protocol biopsies (PBs) into standard care for kidney transplant recipients varies widely. This study aims to review the literature on the practice, histopathological findings, and benefits of performing PB on allograft function. Materials and Methods: A systematic review was conducted using PubMed, ScienceDirect, and other databases from 2000 to 2023. Studies describing findings of PBs within 2 years posttransplant were included. Data extraction covered study design, immunosuppression, biopsy timing, incidence of subclinical rejection (SCR), clinical rejection, and allograft function measures. Statistical analysis was performed using R and RevMan software. Results: Among 25 studies (3384 patients) included, 8 were randomized controlled studies. Protocol biopsy timing varied, with the highest number performed at 1 year (44.84%). The pooled incidence of SCR was 13%, with heterogeneity across estimates. Subgroup analysis did not reveal significant differences in SCR rates between high- and low-immunologic risk patients. Patients who underwent PBs had lower clinical rejection rates (12.64% vs. 20.17%) and better allograft function. Incidence of calcineurin inhibitor toxicity ranged from 1.2% to 63.4%, and BK virus nephropathy ranged from 0% to 5.9% in included studies. Conclusion: Performing PB at 6 months, 1 year, and 2 years posttransplant can reveal SCR and potentially improve long-term graft outcomes. Treatment of SCR may reduce clinical rejection episodes. However, further research, particularly comparing PB with noninvasive methods, is needed to better understand their efficacy and complications in the modern transplant landscape.