Extended valganciclovir prophylaxis in D+/R- kidney transplant recipients is associated with long-term reduction in cytomegalovirus disease: two-year results of the IMPACT study.

Background: Whether the early reduction in cytomegalovirus (CMV) disease seen at 1 year with prolongation of antiviral prophylaxis (up to 200 days) persists in the long term is unknown.
Methods: This international, randomized, prospective, double-blind study, compared 318 CMV D+/R- kidney transplant recipients receiving valganciclovir (900 mg) once daily for up to 200 days vs. 100 days. Long-term outcomes including CMV disease, acute rejection, graft loss, patient survival, and seroconversion were assessed.
Results: At 2 years posttransplant, CMV disease occurred in significantly less patients in the 200- vs. the 100-day group: 21.3% vs. 38.7%, respectively (P<0.001). Between year 1 and 2, there were only 10 new cases of CMV disease; 7 in the 200-day group and 3 in the 100-day group. Patient survival was 100% in the 200-day group and 97% in the 100-day group (p=not significant). Biopsy-proven acute rejection and graft loss rates were comparable in both groups (11.6% vs. 17.2%, P=0.16, and 1.9% vs. 4.3%, P=0.22, in the 200-day vs. 100-day groups, respectively). Seroconversion was delayed in the 200-day group but was similar to the 100-day group by 2 years posttransplant (IgM or IgG seroconversion; 55.5% in the 200-day group vs. 62.0% in the 100-day group at 2-years; P=0.26). Assessment of seroconversion at the end of prophylaxis was of limited utility for predicting late-onset CMV disease.
Conclusion: Extending valganciclovir prophylaxis from 100 to 200 days is associated with a sustained reduction in CMV disease up to 2 years posttransplant.