The effects of preemptive therapy using a very low threshold of pp65 antigenemia to prevent cytomegalovirus disease in kidney transplant recipients: a single-center experience.

Background. Preemptive therapy is a valid option for cytomegalovirus (CMV) disease prevention in kidney transplant recipients. However, there are controversies regarding the appropriate threshold value to be reached before starting antiviral drugs. The aim of this study was to evaluate the benefit of a low threshold of the CMV pp65 antigeneraia test as a guide to initiate the therapy. Methods. We performed a prospective study on 47 consecutive kidney recipients. The CMV pp65 antigenemia test was performed over 6 months posttransplantation; patients who displayed >= 2/200,000 CMV antigen-positive leukocytes were treated for 2 months with valgancyclovir (450 mg twice a day). Results. Twenty-five patients developed CMV infections, which were initially diagnosed at 55 +/- 25 days posttransplantation. The number of CMV antigen-positive cells/200,000 leukocytes on the first positive test was 17 +/- 22. The test first became negative at 17 +/- 8 days after the diagnosis. A positive correlation was observed between the number of CMV antigen-positive cells and the time to obtain the first negative test (P = .01). At the end of follow-up (35.3 +/- 16.4 months), none of the patients had developed CMV syndrome. Among the CMV-positive recipients, the creatinine levels showed no differences from the values before the CMV infection. No difference in creatinine levels was noted between CMV infection positive versus negative patients. Conclusion. Our data suggested that a CMV antigenemia titer >= 2/200.000 leucocytes can be considered to be an appropriate threshold to start anti-CMV preemptive therapy.