Comparative study of cytomegalovirus viral load versus antigenemia in hospitalized patients from 2011 to 2016: in search of an equivalence

Cytomegalovirus (CMV) infections are highly prevalent in Chile and the world and are relevant in immunosuppressed patients. The most widely used diagnostic and monitoring techniques are CMV antigenemia and viral load (CV). This study compared CMV antigenemia with real-time PCR (RT-PCR) viral load to establish numerical equivalence between both methods. Material and method: CMV antigenemia and viral load were retrospectively analyzed from 2011 to 2016 in 154 samples corresponding to 119 patients (75 men and 44 women) with HIV disease (28.0%), transplant (16.0%) and acute pneumonia (16.0%) and others. A Log10 correlation of the values of both tests was made. Results: The CV presented a higher positivity than the antigenemia (40.3 and 16.9%, respectively). Both methods were concordant in 77.9% and presented a significant correlation (p<0.0001). The numerical equivalence found was: 1) 0 nuclei/400,000 leukocytes = <2000 copies/mL of blood. 2) 1-10 nuclei/400,000 leukocytes = 2,000-4,000 copies/mL of blood. 3) 11-50 nuclei/400,000 leukocytes = 4,001-50,000 copies/mL of blood. 4) >50 nuclei/400,000 leukocytes = to >50,000 copies/mL of blood. Both methods presented a similar behavior against a CMV infection in different types of patients. Conclusions: Real-time PCR turned out to be more sensitive. It was possible to establish an equivalence between the number of nuclei/400,000 leukocytes and the number of CMV copies/mL of blood, which suggests that both methods can be used interchangeably to make clinical decisions.