Graft loss among renal-transplant recipients with early reduction of immunosuppression for BK viremia

AIM To review the incidence of graft loss and acute rejection among renal transplant recipients with early reduction of immunosuppression for BK viremia.METHODS We performed a retrospective analysis of consecutive de-novo kidney-only transplants from January 2009 to December 2012 to evaluate the incidence of Polyomavirus associated nephropathy(PyV AN). Recipient plasma was screened for BKV DNA via quantitative polymerase chain reaction(PCR) at months 1,3,6,9 and 12 post-transplant and on worsening graft function.Immunosuppression was reduced at ≥ 3-log copies/mL. Those with viremia of ≥ 4-log copies/mL(presumptive PyV AN) underwent renal transplant biopsy. Presumptive Py VAN(PP) and definitive Py VAN(DP; biopsy-proven) were treated by immunosuppression reduction(IR) only. RESULTS Among 319 kidney transplant recipients,the median age was 53 years(range 19-83),65.8% were male,and 58.9% were white. Biopsy-proven acute rejection was found in 18.5% within 0-168 wk. Death-censored graft loss occurred in 5.3%(n = 17) and graft loss attributable to PyV AN was 0.6%(n = 2). Forty-seven patients were diagnosed with PP(14.7%) and 18(5.6%) with DP. Graft loss among participants with PyV AN(8.5%) and those without(4.8%) was not significantly different. Deceased donor kidney transplantation(OR = 2.3,95%CI = 1.1-4.6) and AR(OR = 2.3,95%CI = 1.2-4.7) were associated with Py VAN in the multivariate analysis. BK viremia between 3 and 4-log copies/mL occurred in 27 patients,all of whom underwent IR. Of these,16(59%) never developed PyV AN while 11(41%) developed PyV AN(4 DP,7 PP) within a range of 11-39 wk. CONCLUSION Instituting an early reduction of immunosuppression,in the absence of adjunctive antivirals,is effective at preventing PyV AN and may be associated with a lower incidence of graft-loss without a reciprocal increase in the incidence of acute rejection.