BK polyomavirus-associated nephropathy (BKPyVAN) represents a challenge to transplant centers. Prevention using early detection of BKPy viremia (BKPyV) and immunosuppression(IS) reduction is the best current strategy and some centers including ours switch micophenolic acid to mTORi.. We retrospectively evaluated the cut-off of our in-house qPCR reaction to predict BKPyVAN in our population. All adult kidney transplants between Jan 2013-Dec2015 (N=631) were included. Other solid-organ transplantation and patients(pts) who died/graft loss within the 1^st month(mo) were excluded. 577 pts were submitted to BKPyV screening monthly, starting at the 2^nd mo until the 6^th month and then every 3 mo until the first year. Mean follow up was 597 days..IS consisted of steroids/tacrolimus (TAC) along with either mycophenolic acid (n=544) or everolimus (EVL) (n=33).271 (46%) patients developed BKPyV and 31 (5.4%) BKPyVAN, confirmed by biopsy and 306 (53%) no-viremia(NV). Mean TAC trough level did not differ among groups from the 1^st to the 5^th mo. Interestingly, EVL was associated with a higher number of pts with BKPyV, BKPyVAN compared to NV (9vs6vs3%, p=0.023). Demographics were similar except that Asian pts presented more BKPyVAN and BKPyV than NV (6.5%vs2.5×0.3%,p=0.028). Induction with Thymoglobulin (61vs59vs49%, p=0.056) and acute rejection (29vs27vs19%, p=0.057) tended to be higher in BKPyVAN and BKPyV groups than NV.

Median time to first positive BKV was similar in both BKPyVAN and BKPyV (124x 151 days). Median 1^st viremia was not different but the following ones were significantly higher in the former. 76% of the BKPyVAN increased the 2^nd viremia as compared to 56% of BKPyV group (p=0.004). Considering the highest viremia, a ROC curve analysis (AUC= 0.904) showed that a cut-off of 10.000 copies/ml had 97% sensitivity/59% specificity to predict BKPyVAN. A cut-off of 28.000 copies/ml showed 97% sensitivity/75% specificity. These data show that a viremia of 10.000 copies/ml should lead to a second evaluation and if the result increased or reach ≥28.000 copies allograft biopsy and decrease in IS are mandatory.

CITATION INFORMATION: Nihei C, Agena F, Paula F, David D, Fink M, Pierrotti L, David-Neto E. Defining a BKV Cutt-Off and Profile for Early Detection of BKV Associated Nephropathy. Am J Transplant. 2017;17 (suppl 3).

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