Performance evaluation of the Roche cobas 6800 system for quantifying cytomegalovirus DNA in plasma and urine samples

Abstract

Introduction: Cytomegalovirus (CMV) nucleic acid amplification testing is important for CMV infection diagnosis and management. CMV DNA is found in plasma and various other fluids, including urine. If CMV can be reliably detected in urine, it may be considered a non-invasive alternative to blood tests. The cobas 6800 system (Roche Diagnostics, Mannheim, Germany) is a Food and Drug Administration-approved testing platform for measuring CMV DNA in plasma.

Objective: To evaluate the analytical performance of the cobas 6800 system and compare the clinical feasibility of CMV detection in plasma and urine samples.

Study design: Imprecision, linearity, limit of quantitation (LOQ), and cross-reactivity of the cobas 6800 system were assessed, and reference interval verification was performed. Plasma CMV DNA quantification was compared to CMV DNA values in urine samples obtained from 129 pediatric patients (<18 years of age) from March 2020 to May 2020 at a tertiary hospital.

Results: The assay precision was within the acceptable range. Linearity was observed within the tested concentration range (2.36-6.33 log IU/mL) with a coefficient of determination of 0.9972. The LOQ was 34.5 IU/mL. The assay did not show cross-reactivity with 15 other viruses. Plasma and urine detection results were stratified into three categories: negative, <LOQ, and positive to analyze the degree of agreement with the results. The quadratic weighted kappa value was 0.623 (P = 0.000), showing substantial concurrence.

Conclusion: The cobas 6800 system offers good sensitivity, precision, and linearity and is suitable for monitoring CMV viral loads in the plasma and urine samples.