Incidence and Outcomes of BK Virus Nephropathy in Kidney Transplant Recipients With Steroid-Free Maintenance Immunosuppression

Background. BK virus nephropathy (BKVN) is a significant complication in kidney transplant recipients, resulting in graft dysfunction and potentially leading to graft loss. This study aims to investigate the incidence and outcomes of BKVN in kidney transplant recipients receiving steroid-free maintenance immunosuppression in a Latin -American cohort. Methods. Case series study of BKVN among kidney transplant recipients who underwent transplantation between 2008 and 2023. The primary outcome was graft loss caused by BKVN, excluding death with function. Secondary outcomes included graft function and acute rejection episodes. The statistical analysis involved descriptive statistics and the Kaplan-Meier (K-M) method to plot the overall probabilities of not initiating dialysis. Results. During the 15-year period, 2236 kidney transplants were performed, BKVN was histologically diagnosed in 38 kidney recipients and 33 cases were analyzed. Median age was 50 years and men were 48.5% of patients. A total of 45.4% of BKVN occurred within the first 12 months of transplant. The incidence of BKVN was 1.6% but it varied by era. The rate of graft loss was 75.7% (25 cases). The K-M graft survival probability at 6 months and 12 months after diagnosis of BKVN was 38.3% (95% CI 24.7-59.4) and 22.3% (95% CI 11.7-42.8), respectively. Conclusion. BKVN affected 1.6% of transplant recipients and it was associated with high-rate of graft loss. We observed that significant graft disfunction at the time of diagnosis resulted in worse outcomes with a reduced probability of graft survival.