The use of hepatitis B virus (HBV)-positive donor kidneys to expand the donor pool has been implemented, but limited evidence exists regarding their impact on transplant outcomes. This study aimed to investigate the effects of donor HBV infection on transplant outcomes. Methods: Donor and recipient data between 2015 and 2021 were collected. A total of 743 kidney transplant cases were screened, including 94 donor hepatitis B surface antigen (HBsAg)+/recipient HBsAg– (D+R–) and 649 donor HBsAg–/recipient HBsAg– (D–R–) cases. The analysis endpoints included recipient HBV infection, delayed graft function (DGF), peak estimated glomerular filtration rate (eGFR) within 12 months, recipient survival, and death-censored graft survival (DCGS). Results: The D+R– group had a significantly higher risk of HBV infection compared to the D–R– group (6/72 vs. 3/231; relative risk, 6.4; p = 0.007). The risk of HBV transmission decreased significantly with increasing hepatitis B surface antibody (HBsAb) titer (p for trend = 0.003). Furthermore, the D+R– group did not exhibit an increased risk of DGF compared to the D–R– group (odds ratio, 0.70; p = 0.51) in the multivariable mixed model. Both groups had similar peak eGFR within 12 months (β = 1.01, p = 0.71), and this had no impact on patient survival (hazard ratio [HR], 0.36; p = 0.10) and DCGS (HR, 0.79, p = 0.59) in the shared-frailty Cox model. Conclusion: The use of HBsAg-positive donor kidneys appears relatively safe for HBV-immunized recipients in the short term. D+R– does not negatively affect graft function recovery and provides comparable posttransplant outcomes. Maintaining an HBsAb titer over 100 mIU/mL before transplantation is critical to reduce the risk of HBV transmission.

Background::The calcineurin inhibitor (CNI)-based immune maintenance regimen that is commonly used after renal transplantation has greatly improved early graft survival after transplantation; however, the long-term prognosis of grafts has not been significantly improved. The nephrotoxicity of CNI drugs is one of the main risk factors for the poor long-term prognosis of grafts. Sirolimus (SRL) has been employed as an immunosuppressant in clinical practice for over 20 years and has been found to have no nephrotoxic effects on grafts. Presently, the regimen and timing of SRL application after renal transplantation vary, and clinical data are scarce. Multicenter prospective randomized controlled studies are particularly rare. This study aims to investigate the effects of early conversion to a low-dose CNI combined with SRL on the long-term prognosis of renal transplantation.Methods::Patients who receive four weeks of a standard regimen with CNI + mycophenolic acid (MPA) + glucocorticoid after renal transplantation in multiple transplant centers across China will be included in this study. At week 5, after the operation, patients in the experimental group will receive an additional administration of SRL, a reduction in the CNI drug doses, withdrawal of MPA medication, and maintenance of glucocorticoids. In addition, patients in the control group will receive the maintained standard of care. The patients’ vital signs, routine blood tests, routine urine tests, blood biochemistry, serum creatinine, BK virus (BKV)/cytomegalovirus (CMV), and trough concentrations of CNI drugs and SRL at the baseline and weeks 12, 24, 36, 48, 72, and 104 after conversion will be recorded. Patient survival, graft survival, and estimated glomerular filtration rate will be calculated, and concomitant medications and adverse events will also be recorded.Conclusion::The study data will be utilized to evaluate the efficacy and safety of early conversion to low-dose CNIs combined with SRL in renal transplant patients.Trial registration::Chinese Clinical Trial Registry, ChiCTR1800017277.