Factors influencing cytomegalovirus DNA load measurements in whole blood and plasma specimens from allogeneic hematopoietic stem cell transplant recipients.

We assessed the impact of several parameters, including the nature of the episode of Cytomegalovirus (CMV) DNAemia, the use of preemptive antiviral therapy, and the blood cell content in CMV DNA loads measured in whole blood (WB) and plasma (PL). CMV DNA load was quantified in 245 paired specimens collected within 43 postengraftment episodes of CMV DNAemia by using the CMV RealTime CMV PCR (Abbott Molecular). Concordant categorical results were obtained for 78.4% of paired specimens (Kappa index, 0.385; P = <0.001). Overall, CMV DNA loads in PL were higher than those in WB (mean bias, +0.115 log IU/mL) in both initial and recurrent episodes; this was so in post-antiviral treatment but not in pretreatment paired specimens. Median CMV DNA doubling time values in both compartments were not significantly different. Leukocyte counts had a significant impact on the comparability of CMV DNA loads measured in both matrices.