Performance of a completely automated system for monitoring CMV DNA in plasma

Background: Completely automated systems for monitoring CMV-DNA in plasma samples are now available. Objectives: Evaluate analytical and clinical performances of the VERIS (TM)/MDx System CMV Assay (R). Study design: Analytical performance was assessed using quantified quality controls. Clinical performance was assessed by comparison with the COBAS (R) Ampliprep (TM)/COBAS (R) Taqman CMV test using 169 plasma samples that had tested positive with the in-house technique in whole blood. Results: The specificity of the VERIS (TM)/MDx System CMV Assay (R) was 99% [CI 95%: 97.7-100]. Intra-assay reproducibilities were 0.03, 0.04, 0.05 and 0.04 log(10) IU/ml (means 2.78, 3.70, 4.64 and 5.60 log(10) IU/ml) for expected values of 2.70, 3.70, 4.70 and 5.70 log(10) IU/ml. The inter-assay reproducibilities were 0.12 and 0.08 (means 6.30 and 2.85 log(10) IU/ml) for expected values of 6.28 and 2.80 log(10) IU/ml. The lower limit of detection was 14.6 IU/ml, and the assay was linear from 2.34 to 5.58 log(10) IU/ml. The results for the positive samples were concordant (r = 0.71, p < 0.0001; slope of Deming regression 0.79 [CI 95%: 0.56-1.57] and y-intercept 0.79 [CI 95%: 0.63-0.95]). The VERIS (TM)/MDx System CMV Assay (R) detected 18 more positive samples than did the COBAS (R) Ampliprep (TM)/COBAS (R) Taqman CMV test and the mean virus load were higher (0.41 log(10) IU/ml). Patient monitoring on 68 samples collected from 17 immuno-suppressed patients showed similar trends between the two assays. As secondary question, virus loads detected by the VERIS (TM)/MDx System CMV Assay (R) were compared to those of the in-house procedure on whole blood. The results were similar between the two assays ( -0.09 log(10) IU/ml) as were the patient monitoring trends. Conclusion: The performances of the VERIS (TM)/MDx System CMV Assay facilitated its routine use in monitoring CMV-DNA loads in plasma samples. (C) 2016 Elsevier B.V. All rights reserved.