Dynamics of cytomegalovirus (CMV) plasma DNAemia in initial and recurrent episodes of active CMV infection in the allogeneic stem cell transplantation setting: implications for designing preemptive antiviral therapy strategies.

Preemptive antiviral therapy strategies for active cytomegalovirus (CMV) infection occurring in allogeneic stem cell transplant recipients should be optimized to avoid overtreatment. The current study was aimed at determining whether the analysis of the kinetics of CMV DNA load in plasma may provide useful information for the therapeutic management of active CMV infection in this setting. A total of 59 consecutive patients were included in the study, of which 40 (67.8%) developed 1 (n = 21) or more (n = 19) episodes of CMV DNAemia. The need for antiviral therapy for initial or secondary episodes of CMV DNAemia could not be predicted on the basis of the CMV DNA load value in the first plasma testing positive by polymerase chain reaction (PCR). In contrast, in the absence of antiviral therapy, an increase of ≥3-fold between the baseline CMV DNA load and that measured a median of 6 days later discriminated between initial episodes eventually requiring antiviral treatment and those resolving spontaneously (sensitivity, 76.4%; specificity, 89.4%; positive predictive value, 86.6%; negative predictive value, 80.9%). This criterion was not useful for identifying recurrent episodes of CMV DNAemia that required antiviral therapy. The CMV doubling time and CMV DNA loads at the time of the first positive PCR and at initiation of preemptive therapy did not differ significantly between episodes that responded immediately to antiviral therapy from those showing a delayed response. The analysis of the dynamics of CMV DNA load in plasma in the absence of antiviral therapy allowed early recognition of episodes of CMV DNAemia that eventually needed to be treated, but did not permit prediction of the kinetics of CMV DNA clearance in response to antiviral therapy.