Use of First Positive Cytomegalovirus (CMV) PCR Determination to Differentiate a Viral Blip From Established CMV Infection in Transplant Recipients
Background: CMV infection frequently complicates the course after solid organ or haematopoietic stem cell transplantation. A pre-emptive strategy relies on regular screening with CMV PCR of recipients to diagnose and promptly treat the infection while still asymptomatic. The PCR technology is known in HIV to also identify isolate positive reads – so called blips – that do not require medical intervention. Whether such viral blips exist also for CMV in the transplant setting remains unknown. We wanted to determine the prevalence and risk factors for developing viral blips while screening transplant recipients with CMV PCR in our cohort.
Methods: In a large unselected cohort of transplant recipients, consecutive situations were identified characterised by a triplicate of CMV PCRs during follow-up where the 1st PCR was undetectably low, the 2nd was positive and the interval between the 2nd and 3rd PCR was < 8 days apart. The situation was defined as either a viral blip or an established infection depending on whether the 3rd PCR was again undetectably low or still positive, respectively. Using logistic regression, the impact of the following factors on the % of situations being classified as blips were investigated: viral load of the 2nd PCR, type of transplantation, CMV IgG serostatus of donor and recipient, and use of treatment.
Results: Of a total of 402 scenarios fulfilling criteria above, 126 were classified as blips (31%). The proportion of blips was higher the lower the viral load of the 2nd PCR (table); the adjusted odds ratio (OR) of a blip (versus 2nd PCR just positive = 273 IU/mL) was 0.12 ([0.04-0.4] p<0.001), and 0.03 ([0.003-0.2] p<0.001)) when viral load was 2,730-9,100 or > 9,100 IU/mL, respectively, whereas OR was comparable with the group just positive if viral load levels was 273-2,730 IU/mL. The results were unaffected by use of anti CMV treatment.
Conclusion: Viral blips are frequent while screening transplant recipients with CMV PCR, in particular if the viral load of the first positive PCR is low. Our findings imply that in asymptomatic patients, a first positive CMV PCR viral load < 2,730 IU/mL should be confirmed before initiation of antiviral therapy, as otherwise more than 40% of patients will receive unnecessary antiviral medication.
F. Gustafsson, None
M. Iversen, None
N. Kirkby, None
A. Rasmussen, None
S. Schwartz Sørensen, None
H. Sengeloev, None
L. Vindeloev, None
J. Lundgren, None