Assessment of an automated Cytomegalovirus nucleic acid amplification test using clinical plasma, bronchoalveolar lavage, and tissue specimens

Background: Cytomegalovirus (CMV) causes significant morbidity and mortality in immunocompromised patients, particularly transplant recipients. Quantitation of CMV DNA in peripheral blood is used to monitor prophylactic and pre-emptive approaches to prevent CMV disease, whereas CMV DNA testing of non-plasma specimens may aid in the diagnosis of end-organ disease. Methods: The analytical performance of the FDA-approved Aptima CMV Quant Assay was evaluated using reference CMV (SeraCare) diluted in defibrinated human plasma, as well as negative bronchoalveolar lavage fluid and tissue. Agreement was determined using 100 clinical acid-citrate-dextrose (ACD) plasma specimens, 77 bronchoalveolar lavage (BAL) fluids, and 101 tissues previously tested using artus CMV qPCR. Results: Aptima CMV lower limit of detection (LLOD) was 169 IU/mL for ACD plasma, 100 IU/mL for BAL, and 50 IU/mL for tissue. Positive percent agreement (PPA) was 100.0% (50/50; 95% CI: 92.9% - 100.0%) and negative percent agreement (NPA) was 94.0% (47/50; 95% CI: 83.5% - 98.8%) for ACD plasma. Bland-Altman analysis revealed a bias of 0.20 log10 IU/mL (Aptima - artus) with 95% limits of agreement of -0.53 to 0.93. For BAL fluids, PPA was 70.0% (14/20; 95% CI: 45.7% - 88.1%) and NPA was 82.4% (43/51; 95% CI: 69.1% - 91.6%). For tissues, PPA was 90.0% (45/50; 95% CI: 78.2% - 96.7%) and NPA was 94.0% (47/50; 95% CI: 83.5% - 98.8%). Conclusions: The Aptima CMV Quant Assay demonstrates high analytical sensitivity and good overall agreement using clinical plasma and tissue specimens.