Background. Electrochemiluminescence (ECLIA) immunoassays Elecsys®: Anti-HCV II, HBsAg II, HIV and Syphilis combi PT produced by Roche Diagnostics are dedicated to blood donor screening and clinical sample testing on a fully automated cobas e 601 analyzer.
The aim was to evaluate the usefulness of the Elecsys® assays for blood donor screening in Poland; analysis of assay specificity, sensitivity, repeatability and reproducibility (S/CO).
Material and methods. Specificity evaluation was based on analysis of 2 508 donations from first-time and repeat donors. Clinical sensitivity was estimated on the basis of test results of: 1) seroconversion panels (SeraCare, BBI), 2) panel of seropositive samples (confirmed) infected with genotypes most common in Poland; panels included dilutions of several seropositive samples, 3) donations positive in NAT Assays/negative in routine serological screening (NAT yields). With the exception of NAT yield samples, all studies were performed in parallel with reference CMIA tests.
Results. Test specificity was as follows: anti-HCV II — 99.8%, HBsAg II — 100%, HIV combi PT — 99.6%, Syphilis — 99.9%. The number of reactive results obtained with HBsAg II, HIV combi PT and Syphilis assays in seroconversion panels was the same as with reference tests. In SeraCare seroconversion panels the Anti-HCV II assay detected HCV antibodies in two earlier panel samples which went undetected in the reference test. For undiluted seropositive samples, the clinical sensitivity was estimated at 100%. Reactive results were obtained in HCV infected samples with dilutions from 1 : 50 to 1 : 1600 (18 reactive /18 tested dilutions), whereas in the reference CMIA test reactive results were reported in samples diluted up to 1 : 200 (9 reactive/18 tested dilutions). For HIV reactivity was detected in 9/18 dilutions, for HBV in 11/15, and for Syphilis in 7/9. The reference test detected infectious markers less frequently; 7/18, 10/15 and 6/9 for HIV, HBV and Syphilis respectively. Clinical sensitivity based on NAT yields was 12% for HCV (11/91), 6% for HBV (6/99) and 14% for HIV (1/7). The coefficient variation (CV) for repeatability and reproducibility of results expressed in S/CO was < 20%. During the evaluation period no invalid result was obtained and no analyzer failure was reported.
Conclusions. Automated Elecsys® assays: Anti-HCV II, HBsAg II, HIV and Syphilis combi PT performed on the cobas e601 analyzer (Roche) present satisfactory specificity, sensitivity and reproducibility and repeatability of results (S/CO). They can therefore be used for screening of Polish blood donors.