Risk Factors for the Development of BK Polyomavirus and Treatment Outcomes in Kidney Transplant Recipients: An 8-Year Retrospective Cohort Study.

Background: BKPyV-DNAemia occurs in up to 30% of kidney transplant recipients (KTRs), with graft-threatening BKPyV-nephropathy in up to 10%. Risk factors for BKPyV-DNAemia, BKPyV-nephropathy, and associated graft loss are incompletely described. We sought to determine the prevalence, risk factors for, and long-term impact of BKPyV-DNAemia.

Methods: A single-centre retrospective study of adult KTRs between 2010 and 2018. We used logistic regression to determine odds ratios (OR) of BKPyV-DNAemia, and survival analysis to assess the impact of BKPyV-DNAemia on graft and patient survival.

Results: Of 522 patients, 100 (19%) developed BKPyV-DNAemia and 43 (8.2%) developed BKPyV-nephropathy, resulting in the loss of two grafts. Factors associated with the development of BKPyV-DNAemia were non-Caucasian ethnicity (OR 1.76, CI 0.98-3.16), pre-transplant diabetes (OR 2.06, CI 1.02-4.14) and HLA mismatch of 3/6 or 4/6 (OR 2.37, CI 1.06-5.56) and HLA mismatch of 5/6 and 6/6 (OR 2.53, CI 1.20-5.63). Additionally, a greater than 25 mg per day prednisolone dose following acute transplant and acute rejection in the first month post-transplant was associated with an increased risk of BKPyV-DNAemia (OR 3.06, CI 1.66-6.06 and OR 2.36, CI 1.16-4.75 respectively). Over a 10-year follow-up, the development of BKPyV-DNAemia and BKPyV-nephropathy was not associated with reduced graft or patient survival.

Conclusion: While BKPyV-DNAemia and BKPyV-nephropathy remain prevalent in KTR, there were low rates of associated graft loss and no demonstrable impact on long-term graft or patient survival.