RESUMO
BACKGROUND: Several studies on standardisation of NAT assays for diagnosis of hepatitis C virus (HCV) infection have been carried out in European countries. In fact the widespreading use of nucleic acid amplification technology (NAT) in diagnostic centres for the evaluation of the HCV infection, requires the application of reference external standards to control laboratory performance; but up to date they are not routinely used. OBJECTIVES: Fifteen diagnostic centres of major Italian Hospitals participated to a quality control study for the standardisation of polymerase chain reaction (PCR)-based HCV-RNA detection, organised by the Committee for the Study of Biotechnology (CoSBio) of the Italian Society of Clinical Microbiology (AMCLI). All the participant centres (PC) used commercial assays, automated or semi-automated. STUDY DESIGN: The study was performed in four rounds. Altogether each centre received 14 reference negative and 22 reference positive sera. The range of copies number per ml of the reference positive sera was 10(4)-10(7). RESULTS AND CONCLUSIONS: Considering the 540 samples tested, 4.54% of false negative (FN) and 4.28% of false positive (FP) results were reported. Thereafter the sensitivity and the specificity were 95.65 and 95.89%, respectively. The errors were distributed among seven out of the 15 PCs. The percentage of FP results was uniformly distributed in each shipment, whereas FN results emerged with the sera at lower HCV genome copies number. The analysis of the data obtained suggests that FP as well as FN results may be attributable to errors or to others problems of laboratories. To improve the performance of Italian, as well as of laboratories throughout the world, the use of external reference standards in multicentre collaborative studies will be required.