(Vienna, 24 July 2025) Infections or reactivations of the BK polyomavirus are among the most common complications following kidney transplantation. The transplant itself is affected and can be permanently damaged by uncontrolled virus replication. As there are currently no effective drugs against the virus, early detection of high-risk patients is crucial. A systematic analysis has now investigated which risk factors can influence BK virus complications. Certain drugs have been associated with an increased risk – at the same time, it became clear that no single factor is decisive on its own. The decisive factors remain their interaction and the individual immune competence required to control virus replication in the transplant. The results were published in the journal Kidney International.
BK polyomavirus nephropathy is a common cause of transplant damage after kidney transplantation. Until now, the assessment of risk factors has been based largely on small or retrospective case studies. Michael Eder and colleagues from the Clinical Division of Nephrology and Dialysis at the Department of Medicine III at MedUni Vienna have published a comprehensive systematic literature review including a meta-analysis. The aim was to identify modifiable risk factors for BK polyomavirus-associated complications (BKPyV) after kidney transplants.
Over 6,600 scientific papers were reviewed for the analysis, of which 165 studies with a total of around 197,000 patients were included in the evaluation. The effects of various immunosuppressants were investigated, in particular tacrolimus compared to cyclosporine, the use of corticosteroids, rituximab, mycophenolate mofetil, mTOR inhibitors and antithymocyte globulin compared to IL-2 receptor antagonists. The influence of ABO blood group incompatibility between donor and recipient and the use of ureteral stents were also analyzed.
The results show that corticosteroids are associated with an increased risk for three of the four viral complications investigated. A significant association was also found for tacrolimus and antithymocyte globulin in two endpoints each. Individual risk associations were found with tacrolimus blood levels, ABO incompatibility, rituximab, mycophenolate, mTOR inhibitors and ureteral stents.
The publication analyses modifiable factors on the largest scale to date and strengthens the existing evidence. Despite the associations identified, the results suggest that the risk factors are not decisive individually, but rather in combination with each other and, consequently, the resulting individual immune competence. However, the fact that most risk factors are also important drugs for preventing rejection, underscores the complexity of the problem and the need for effective antiviral drugs and personalized concepts for optimal transplant follow-up care.
Publication: Kidney International
A systematic literature review and meta-analysis evaluated modifiable risk factors for the development of BK polyoma virus-associated complications
Michael Eder, Alexander Kainz, Haris Omic, Christof Aigner, Dragan Copic, Camille N Kotton, Nassim Kamar, David Wojciechowski, Hans H Hirsch, Rainer Oberbauer
Kidney Int. 2025 Jul 2:S0085-2538(25)00506-X. doi: 10.1016/j.kint.2025.06.014