title: Conversion to a sirolimus-based regimen is associated with lower incidence of BK viremia in low-risk kidney transplant recipients.
abstract: BACKGROUND
  BK viral nephropathy is an increasingly recognized cause of early allograft loss in kidney transplantation. This study aimed to determine whether a sirolimus (Sir)-based calcineurin inhibitor-sparing regimen is associated with a lower incidence of BK viremia.
  
  
  METHODS
  This was a single-center retrospective study. Patients were either on tacrolimus (Tac)-based or on Sir-based immunosuppression. Conversion from Tac to Sir occurred at or after 3 months if patients were <62 years of age, had calculated panel reactive antibodies of <20%, and did not have acute early rejection.
  
  
  RESULTS
  Incidence of clinically significant BK viremia was 17.9% in the Tac group and 4.3% in the Sir group. Cox regression multivariate analysis showed that male gender (hazard ratio [HR] = 2.87) and switch to Sir (HR = 0.333) impacted the incidence of BK viremia. Kaplan-Meier analysis showed a higher BK-free survival in the Sir group. A trend was seen toward shorter time to resolution of BK viremia and lower peak viremia in the Sir group. Patients on Sir had a higher estimated glomerular filtration rate at each time point; 34% of patients discontinued Sir because of side effects.
  
  
  CONCLUSIONS
  Conversion to Sir-based maintenance immunosuppression at or about 3 months after kidney transplantation correlates with a lower incidence of BK viremia.
authors.affiliation: Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.
authors.forename: F A
authors.initials: FA
authors.lastname: Tohme
authors.forename: R S
authors.initials: RS
authors.lastname: Kalil
authors.forename: C P
authors.initials: CP
authors.lastname: Thomas
mesh_terms: D000328:Adult; D000368:Aged; D001739:BK Virus / Q000187:drug effects*; D005260:Female; D006801:Humans; D007165:Immunosuppression Therapy; D007166:Immunosuppressive Agents / Q000627:therapeutic use*; D015994:Incidence; D016030:Kidney Transplantation / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D027601:Polyomavirus Infections / Q000188:drug therapy / Q000517:prevention & control*; D012189:Retrospective Studies; D020123:Sirolimus / Q000627:therapeutic use*; D016559:Tacrolimus / Q000627:therapeutic use*; D066027:Transplant Recipients; D014412:Tumor Virus Infections / Q000188:drug therapy / Q000517:prevention & control*; D014766:Viremia
chemical_list: D007166:Immunosuppressive Agents; D020123:Sirolimus; D016559:Tacrolimus
keywords: BK virus; calcineurin inhibitor sparing; kidney transplantation; sirolimus; tacrolimus