P1759NEPHROTOXICITY OF CALCINEURIN INHIBITORS AS A RISK FACTOR FOR BK VIRUS REPLICATION AFTER KIDNEY TRANSPLANTATION

Abstract

Abstract Background and Aims BK virus nephropathy (BKVN) represents a serious complication of kidney transplantation and is responsible for significant percentage of transplanted kidneys prematurely terminating their function. Its occurrence is considered a complication of immunosuppressive therapy and is closely related to its intensity. The aim of our prospective study was to evaluate the incidence of subclinical and clinically manifest nephrotoxicity of calcineurin inhibitors (CI) in repeated protocol kidney graft biopsies as a manifestation of excessive immunosuppression and to evaluate its relationship to the PCR confirmed active BKV replication and bioptically proven BKVN during the first year after transplantation. Method In a group of 161 newly transplanted patients we prospectively evaluated 457 consecutive protocol renal biopsies performed within the first year after transplantation. Using the CI nephrotoxicity score, the incidence of nephrotoxicity was monitored. Findings were correlated with laboratory (PCR) and histological evidence of active BK virus (BKV) replication and BKVN. Results When compared to the normal histology, nephrotoxicity was associated with more frequent significant BKV viraemia and viruria (P = 0.02 and P = 0.01, respectively) and more common occurrence of BKVN. The persistence of toxicity in the subsequent biopsy proved to be a negative risk factor of significant BKV viraemia and viruria (P = 0.03 and P = 0.01, respectively), independently of the initial BKV status of the monitored groups. Toxicity could also be used as a predictor of significant viraemia and viruria (P = 0.02 and P = 0.01, respectively) even in the absence of viral replication at the time of initial biopsy. Conclusion Early histological detection of CI nephrotoxicity followed by pre-emptive CI dose reduction might prevent significant BKV reactivation in the risky first posttransplant year. The evaluation whether a regression of histological signs of nephrotoxicity after a CI dose reduction leads to a reduction in BKV replication, and whether a more frequent occurrence of rejection does not complicate further posttransplant course, will be the subject of our further investigation. Supported by grant of Ministry of Health, Czech Republic DRO (FNOL 00098892) – 87-68.