External quality assessment for the detection of HCV RNA, HIV RNA and HBV DNA in plasma by nucleic acid amplification technology: A novel approach

Department of Infectious, Parasitic and Immune-mediated Diseases, Istituto Superiore di Sanità, Rome, Italy.
Vox Sanguinis (Impact Factor: 2.8). 04/2008; 95(1):8-12. DOI: 10.1111/j.1423-0410.2008.01047.x
Source: PubMed


In this EQA study a novel approach was used to assess the performance of blood centres and blood product manufacturers in detecting the possible contamination of plasma with HCV, HIV and HBV by NAT.
A panel of 12 samples, three negative and three positive for each virus, was distributed to the EQA participants. The positive samples were prepared, using the respective WHO standards, in order to obtain a viral concentration of about three times the 95% DL of the methods most commonly used by laboratories involved in blood screening by NAT. Participants were requested to test each sample of the panel on different days, possibly by different operators using their routine NAT assay.
Overall, the participants' performance was satisfactory. In particular, 49 of the 59 participants (83%) were able to correctly identify all samples. Regarding the remaining 10 laboratories, in three cases a deviation from the laboratory's procedure that could be attributed to an operator's mistake was observed, in two cases a possible cross-contamination occurred while in the remaining five cases the failure to detect the positive samples couldn't be ascribed to any relevant deviation in the laboratory's procedure.
The novel design of this EQA study allowed participants to verify their day by day activity as the study was carried out in the context of their routine testing. Under these conditions, it was demonstrated that, despite the high level of automation reached by NAT assays, human errors can still occur.

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    ABSTRACT: Two External Quality Assessment Programmes (EQAPs) were run in 2008 and 2009 to evaluate the proficiency of blood centres in detecting, by nucleic acid amplification techniques (NAT), the possible contamination of plasma with hepatitis C virus (HCV), human immunodeficiency virus (HIV) and hepatitis B virus (HBV). In the EQAP-2008, three customized panels were designed; each containing positive samples with a viral nominal concentration for the three viruses of about three times the 95% DL of the respective commercial NAT assay. In the EQAP-2009, the proficiency of the participants was evaluated with a single panel, independently on the NAT method used. While 84% (102/122) of the participants in the EQAP-2008 correctly identified the positive and negative samples of the panels, in the EQAP-2009 the percentage of proficient laboratories increased to 97% (118/122). Most importantly, in this 2-year experience, we observed a decrease in the number of pre-/postanalytical errors, from 14 in 2008 to two in 2009. The design of these two EQAPs allowed participants to assess the performance of the NAT methods applied in their routine screening of blood donations, not only with respect to analytical errors but also to human errors that, despite the high level of automation reached by NAT methods, can still occur.
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