Roche Diagnostics Solutions Pleasanton, California, United States
Background/Case Studies: Serologic testing required for donations of blood and components in the US includes HBsAg antigen (ag), and antibodies (abs) to HIV, HCV, HBc, HTLV I/II, and syphilis. One-time testing is required for abs to Trypanosoma cruzi (Chagas). Some blood banks selectively screen donations for total (IgG and IgM) abs to Cytomegalovirus (CMV).
High specificity of the assays is required to minimize false positive reactivity resulting in extra testing, potential donor loss and donor anxiety. Tests are performed on more than one platform requiring additional space and consumables, increased instrument maintenance, and staff. A new automated immunoassay solution is available for performing all required and selective tests in the US.
Study
Design/Methods: The Cobas® Pro serology solution consists of the Cobas Pro serology controller, software, the automated Cobas e 801 analyzer, and US Elecsys® donor screening assays. Elecsys assays use electrochemiluminescence (ECLIA) methodology for the qualitative detection of target abs/ag.
Evaluation of specificity for the Elecsys assays: HIV Duo, Anti-HCV II, Anti-HBc II, HTLV-I/II, HBsAg II, Syphilis, Chagas, and Anti-CMV was performed in parallel to comparator devices: Bio-Rad GS HIV-1/HIV-2 PLUS O EIA and GS HBsAg EIA 3.0, Avioq HTLV-I/II Microelisa System, ORTHO® assays: HCV Version 3.0 ELISA Test System, HBc ELISA Test System and T. cruzi ELISA Test System, all run on the Ortho Verseia® Integrated Processor (Ortho); and Abbot Alinity s HIV Ag/Ab Combo on the Alinity s System (Alinity). Beckman Coulter PK® TP System and PK® CMV-PA assays run on the Beckman Coulter PK7300 Automated Microplate System (PK) were the comparator for detection of abs to Treponema pallidum and CMV.
Specificity was determined on samples from first time (FTD) and repeat (RD) blood donors. Only FTD were tested for Chagas and CMV. Discordant results between Elecsys and the comparator included confirmatory and/or supplemental testing, and testing on follow-up samples.
Results/Findings: For the six assays performed on all donations, the overall and FTD percent specificity for Elecsys vs the comparators Ortho/PK/Alinity are shown in Table 1. Specificity of Chagas FTD was the same for Elecsys and Ortho at 99.97 (CI: 99.90, 99.99) and CMV FTD was 99.46 (CI: 99.05, 99.69) with Elecsys vs 99.32 (CI: 98.89, 99.59) with PK. Conclusions: Elecsys assays have high specificity and are comparable to the comparators in FTDs. Differences in overall specificity may be due to a previous culling effect by the comparator assays. The Cobas Pro serology solution is an alternative to current assays and platforms, streamlining workflow and increasing efficiencies on a single platform.
