COMPLICATIONS - INFECTIONS

V. Malyar¹, V. Busch¹, U. Hillebrand¹, S. Reiermann¹, K. Kliche¹, B. Breil², M. Dugas², B. Suwelack^1
1Department Of Internal Medicine D, University of Muenster, Muenster/GERMANY, ²Department Of Medical Informatics And Biomathematics, University of Muenster, Muenster/GERMANY

Body: Introduction: BK-virus infection may lead to BK-virus nephropathy (BKN), which is a serious complication after renal transplantation (RTX) and may lead to allograft loss. Objective was the examination of the prevalence of BK viremia and BKN in a Caucasian renal transplant population and identification of risk factors associated with BK-infection. .Methods: Single-center analysis. Patients (pts) undergoing RTX between 2005 and 2009 with a tacrolimus-based triple-drug immunosuppression (IS) aged ≥18 years with at least one assessment of serum-PCR for BK-virus post-TX were included. PCR was considered positive if >500 copies(cps)/ml. Results: From 311 Caucasian kidney transplant recipients with at least one assessment of BK-PCR, PCR became positive in 58 (18.6%) pts. Nonparametric Mann-Whitney Test identified donor age (odds ratio 1.82, CI 1.00–3.29, p=0.015), the total number of HLA mismatches (OR 2.51, CI 1.38–4.55, p=0.013) and the presence of a mismatch on the HLA-DR locus (OR 2.52, CI 1.09–5.84, p=0.013) to be significantly associated with post-TX prevalence of BK-infection. Among the 58 pts with BK viremia, 28 pts (48%) had virema with >7000 cps/ml, thereof 10 pts with histologically proven BKN (BKN+ group) and 18 pts without BKN or without biopsy (BKN- group). BK viremia appeared 153.6 ± 151.2 days after RTX (mean ± standard deviation) and reached its peak after another 119.5 ± 167.7 days. The median of peak viremia of all pts with copies > 7000/ml was 48068 cps/ml (range 7730-196000000 cps/ml). The peak viremia was significantly higher in the BKN+ group than in the BKN- group: median 762350 cps/ml (range 30217 to 196000000 cps/ml) vs 22866 cps/ml (range 7730 to 352000 cps/ml), p=0.002 in a nonparametric Mann-Whitney Test. IS was reduced after diagnosis. In 11 of 28 pts (39%) with cps >7000/ml, BK virus was cleared. Clearance was reached 216.36 ± 187.7 (mean ± sd) days after peak viremia. Among pts with >7000 cps/ml, 2 pts lost their allograft function due to BKN. Interestingly, BKN was also present in 2 pts with low virus load <3500 cps/ml. Conclusion: Significant BK-viremia and BKN occur frequently after RTX. Pts with a high number of HLA mismatches, particular those with a mismatch on the HLA-DR locus, and pts with a high donor age are prone to post-TX BK-infection. Mostly, viremia occurs within the first post-TX year. In our population, graft loss happened in 2 pts, clearance was achieved in 39% of pts with significant viremia. IS should be reduced significantly at detection of BK-viremia >1000 cps/ml in order to avoid BKN and graft loss.

Disclosure: All authors have declared no conflicts of interest.