Evaluating CMV Risk Stratification, Donor Characteristics, and Post-Transplant Outcomes in Kidney Transplant Recipients: A Retrospective Eurotransplant Center Analysis.

INTRODUCTION: Cytomegalovirus (CMV) infection remains a major complication after kidney transplantation. Prophylactic and preemptive antiviral strategies are central to infection prevention, particularly in high-risk donor-positive/recipient-negative (D+/R-) constellations. While the IMPACT trial suggested that extending valganciclovir prophylaxis to 200 days reduces CMV disease, real-world data remain inconsistent, and the impact of donor characteristics on CMV-related outcomes is incompletely understood. This study evaluated CMV prophylaxis practices, donor characteristics, and post-transplant outcomes in a large single-center kidney transplant cohort.

METHODS: We retrospectively analyzed 635 kidney transplant recipients treated at the University Hospital of Leipzig between 1993 and 2014. Collected data included CMV serostatus, prophylaxis regimen and duration, donor characteristics, viral load, infection timing, and dialysis-free survival. Only patients transplanted between 2001 and 2014 were included in analyses of prophylaxis duration to ensure uniform valganciclovir use. CMV infection was defined as a positive IgM or PCR result post-transplantation. Multivariable regression analyses were used to assess factors associated with CMV replication and dialysis-free survival.

RESULTS: CMV prophylaxis was administered to 37.1% of patients (77% D+/R-, 32.1% D+/R+, 19.6% D-/R+, and 18.3% D-/R-). CMV infection occurred in 20% of the cohort, with the highest incidence observed in D+/R- recipients (28%). In this high-risk group, extended prophylaxis (>200 days) was associated with delayed but not prevented CMV infection, resulting in reduced CMV-free survival (p < .0001), delayed infection onset (p = .023), and higher viral loads (p = .003). Infections occurred predominantly within 1-3 months post-transplant in D+/R- and D+/R+ recipients, whereas D-/R+ patients more frequently exhibited late-onset infection (>12 months). In multivariable analyses, receipt of an expanded criteria donor kidney was independently associated with both reduced dialysis-free survival and increased risk of post-transplant hCMV replication, independent of CMV serostatus and recipient sex.

CONCLUSION: Extended valganciclovir prophylaxis in high-risk D+/R- kidney transplant recipients was associated with delayed but not prevented CMV infection, resulting in reduced CMV-free survival and higher viral loads. In addition, donor characteristics-particularly expanded criteria donor (ECD) status-were independently associated with increased risk of post-transplant CMV replication and reduced dialysis-free survival. These findings suggest that CMV outcomes after kidney transplantation are associated with not only prophylaxis duration but also donor quality, underscoring the need for individualized prophylaxis strategies tailored to both virological risk and graft characteristics.