Effective management of BK viremia (BKPyV-DNAemia) in kidney transplant recipients (KTRs) involves regular monitoring and adjustment of immunosuppression. With this strategy, the majority of patients will clear BK or have ongoing, but non-significant, low-level BKPyV-DNAemia. However, despite adjustments, some will develop more severe sequelae of BK including BKPyV-DNAemia >5 log copies/ml and BK nephropathy, and others may develop de novo DSA (dnDSA) or acute rejection (AR).
This was a single-center study of KTRs transplanted at the University of Wisconsin-Madison between 01/01/2015 and 12/31/2017. In this study, we sought to elucidate characteristics associated with the progression of BKPyV-DNAemia to unfavorable outcomes after decreasing immunosuppressive medications for the management of BK viremia as describe in consensus guidelines.
A total of 224 KTRs fulfilled our selection criteria; 118 (53%) resolved or persistent low DNAemia, 64 (28%) had severe BK/nephropathy, and 42 (19%) developed dnDSA or AR. In multivariable analysis, female gender (HR: 2.05; 95% CI: 1.08-3.90; p=0.02); previous rejection (HR: 2.90; 95% CI: 1.04-8.12; p=0.04), and early infection (HR: 0.81; 95% CI: 0.72-0.90; p 3 (HR: 2.27; HR: 1.01-5.06; p=0.04), and delayed graft function (HR: 4.14; 95% CI: 1.12-15.28; p=0.03) were associated with development of dnDSA and/or rejection.
Our study suggests that almost half of KTRs with BKPyV-DNAemia managed by our immunosuppressant adjustment protocol progress unfavorably. Identification of these risk factors could assist the frontline clinician in creating an individualized immunosuppressive modification plan potentially mitigating negative outcomes.

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