Association of HHV-6 With Outcomes in CMV-seronegative Liver Transplant Recipients With CMV-seropositive Donors Receiving Preemptive Antiviral Therapy

Background. Risk factors, virological parameters, and outcomes associated with HHV-6 viremia in high-risk donor CMV-seropositive and recipient CMV-seronegative (D+R-) liver transplant recipients in the current era are incompletely defined. Methods. The study population consisted of patients in the preemptive therapy (PET) arm of a randomized, controlled trial of PET versus valganciclovir prophylaxis for CMV prevention in D+R- liver transplant recipients. Weekly blood samples through 100 d in the PET group were tested for HHV-6 viremia using a real-time quantitative polymerase chain reaction. Assessments included virological characteristics and relationship with CMV, risk factors, and impact of HHV-6 viremia with outcomes through 12 mo posttransplant. Results. HHV-6 viremia at any level developed in 42% (40 of 96). Older patient age (P = 0.03), longer hospitalization (P = 0.015), and ICU stay at transplantation (P = 0.029) were significantly associated with high-grade viremia. Concurrent HHV-6 and CMV viremia was associated with earlier onset of HHV-6 viremia (P = 0.004), higher HHV-6 area under the curve (P = 0.043), and higher peak HHV-6 viral load (P = 0.006) versus HHV-6 viremia alone. High-grade viremia was independently associated with biopsy-proven rejection within 12 mo (P = 0.045) posttransplant. Conclusions. Among D+R- liver transplant recipients receiving valganciclovir as PET, high-grade HHV-6 viremia was associated with increased age and critical illness in ICU at time of transplant and was independently associated with allograft rejection.