SAN DIEGO—Late-onset BK virus nephropathy (BKVN) in kidney transplant recipients is associated with less adherence to screening guidelines for the virus compared with early-onset BKVN, investigators reported at ID Week.

The finding implies that late-onset BKVN represents progression of undiagnosed earlier-onset BK virus infection, concluded Kathryn Whitaker, MD, and colleagues at the University of Washington in Seattle.

BKVN is a major cause of graft dysfunction and failure in kidney transplant recipients, the authors noted. Current guidelines recommend BKVN screening every 3 months during the first 2 years post-transplant and decreasing immunosuppression upon BK viremia detection.

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Dr. Whitaker’s group conducted a retrospective study of 671 patients who received a kidney transplant from 2008 to 2013  to assess the timing, clinical characteristics, screening adherence, and outcomes of early and late BKVN, either biopsy-proven or presumptive (plasma BK virus concentration greater than 10,000 DNA copies/mL).

At a median of 8.9 months post-transplant, physicians diagnosed BKVN in 97 patients (15 [15.5%] biopsy-proven and 82 presumptive [84.5%]). Of these, 80 were early onset (diagnosed within the first year post-transplant) and 17 were late onset (diagnosed more than 1 year post-transplant). The two groups had similar clinical characteristics (demographics, induction immunosuppression, and rejection episodes) and similar outcomes (renal dysfunction, graft loss, and death).

Among recipients with late-onset BKVN, 14 (82%) had no evidence of BK viremia within the first year post-transplant, whereas 3 (18%) had viremia detected but at a level below 10,000

DNA copies/mL. Adherence to screening was significantly lower in the late- versus early-onset BKVN group (65% vs. 90%).

Dr. Whitaker’s team concluded that improved first-year screening adherence following kidney transplantation may decrease the incidence of late-onset BKVN, and recommendations for BK virus screening beyond the first year after KT should be reassessed.