title: Stabilization of renal function after the first year of follow-up in kidney transplant recipients treated for significant BK polyomavirus infection or BK polyomavirus-associated nephropathy.
abstract: BACKGROUND
  BK polyomavirus virus (BKPyV) screening and immunosuppression reduction effectively prevent graft loss due to BKPyV-associated nephropathy (BKPVAN) during the first year after transplantation. The aim of our study was to evaluate the impact of this infection during longer follow-up periods.
  
  
  METHODS
  We reviewed the outcome of our screening and immunosuppression reduction protocol in 305 patients who received a kidney transplant between March 2008 and January 2013. Quantitative BKPyV DNA surveillance in plasma was performed at 1, 2, 3, 6, 9, and 12 months after transplantation. Patients with significant viremia and/or biopsy-proven BKPVAN were treated with immunosuppression reduction and leflunomide.
  
  
  RESULTS
  During the first post-transplant year, 24 patients (7.9%) developed significant viremia at a median time of 95 days, and 18 patients had BKPVAN; 23 of the 24 (7.5%) were treated according to our protocol (group BKV+); 225 patients (73.8%) did not develop any BK viremia (group BKV-). Allograft function was similar in both groups at 1 month post transplantation (P=.87), but significantly worse at 1 year in the BKV+ group (P=.002). Thereafter, kidney function stabilized in the BKV+ group and no differences in patient and graft survival were seen between the groups after a median follow-up of 4 years.
  
  
  CONCLUSIONS
  We confirm the early occurrence of BKPyV replication after transplantation and the short-term decline in renal function. However, early detection of BKPyV replication, prompt diagnosis, and reduction in immunosuppression may offer long-term benefits for graft function.
authors.affiliation: Département de Médecine, Service de Néphrologie, Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada.
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Simard-Meilleur
authors.affiliation: Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada.
authors.forename: Paule
authors.initials: P
authors.lastname: Bodson-Clermont
authors.affiliation: Département de Médecine, Service de Néphrologie, Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada.
authors.forename: Gilles
authors.initials: G
authors.lastname: St-Louis
authors.affiliation: Département de Médecine, Service de Néphrologie, Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada.
authors.forename: Michel R
authors.initials: MR
authors.lastname: Pâquet
authors.affiliation: Département de Médecine, Service de Néphrologie, Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada.
authors.forename: Catherine
authors.initials: C
authors.lastname: Girardin
authors.affiliation: Département de Médecine, Service de Néphrologie, Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada.
authors.forename: Marie-Chantal
authors.initials: MC
authors.lastname: Fortin
authors.affiliation: Département de Médecine, Service de Néphrologie, Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada.
authors.forename: Héloïse
authors.initials: H
authors.lastname: Cardinal
authors.affiliation: Département de Médecine, Service de Néphrologie, Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada.
authors.forename: Marie-Josée
authors.initials: MJ
authors.lastname: Hébert
authors.affiliation: Département de Médecine, Service de Néphrologie, Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada.
authors.forename: Renée
authors.initials: R
authors.lastname: Lévesque
authors.affiliation: Département de Médecine, Service de Néphrologie, Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada.
authors.forename: Edith
authors.initials: E
authors.lastname: Renoult
mesh_terms: D000328:Adult; D064591:Allografts / Q000473:pathology; D000998:Antiviral Agents / Q000627:therapeutic use*; D001739:BK Virus / Q000302:isolation & purification* / Q000502:physiology; D001706:Biopsy; D004279:DNA, Viral / Q000302:isolation & purification; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate; D006085:Graft Survival / Q000187:drug effects; D006801:Humans; D007150:Immunohistochemistry; D007165:Immunosuppression Therapy / Q000009:adverse effects* / Q000379:methods; D007555:Isoxazoles / Q000627:therapeutic use; D007674:Kidney Diseases / Q000097:blood / Q000150:complications / Q000188:drug therapy* / Q000821:virology; D016030:Kidney Transplantation / Q000009:adverse effects*; D000077339:Leflunomide; D008297:Male; D008875:Middle Aged; D027601:Polyomavirus Infections / Q000097:blood / Q000150:complications / Q000188:drug therapy* / Q000821:virology; D012189:Retrospective Studies; D066027:Transplant Recipients; D014184:Transplantation, Homologous / Q000009:adverse effects; D014412:Tumor Virus Infections / Q000097:blood / Q000150:complications / Q000188:drug therapy* / Q000821:virology; D014766:Viremia / Q000150:complications / Q000188:drug therapy* / Q000453:epidemiology / Q000821:virology; D014779:Virus Replication
chemical_list: D000998:Antiviral Agents; D004279:DNA, Viral; D007555:Isoxazoles; D000077339:Leflunomide
keywords: BK polyomavirus; immunosuppression; kidney transplant; nephropathy