Nation-wide measure of variability in HCMV, EBV and BKV DNA quantification among centers involved in monitoring transplanted patients.

Background: Inter-laboratory variability in quantifying pathogens involved in viral disease following transplantation may have a great impact on patient care, especially when pre-emptive strategies are used for prevention.

Objectives: The aim of this study was to analyze the variability in quantifying CMV, EBV and BKV DNA from 15 virology laboratories of the Italian Infections in Transplant Working Group (GLaIT) involved in monitoring transplanted patients.

Study Design: Panels from international Quality Control programs for Molecular Diagnostics (QCMD, year 2012), specific for the detection of CMV in plasma, CMV in whole blood (WB), EBV and BKV were used. Intra- and inter-laboratory variability, as well as, deviations from QCMD consensus values were measured.

Results: 100% specificity was obtained with all panels. A sensitivity of 100% was achieved for EBV and BKV evaluations. Three CMV samples, with concentrations below 3 log10 copies/ml, were not detected by a few centers. Mean intra-laboratory variability (% CV) was 1.6 for CMV plasma and 3.0 for CMV WB. Mean inter-laboratory variability (% CV) was below 15% for all of the tested panels. Inter-laboratory variability was higher for CMV in WB with respect to the CMV plasma panel (3.0 vs 1.6% CV). The percentiles 87.7%, 58.6%, 89.6% and 74.7% fell within±0.5 log10 difference of the consensus values for CMV plasma, CMV WB, EBV and BKV panels, respectively.

Conclusions: An acceptable intra- and inter-laboratory variability, in comparison with international standards was observed in this study. However, further harmonization in viral genome quantification is a reasonable goal for the future.