A-295 A Multicenter Evaluation of the Access Syphilis Assay on the DxI 9000 and Access 2 Immunoassay Analyzers

Abstract Background Beckman Coulter, Inc. has developed a fully automated Access Syphilis assay* for use on the DxI 9000 and Access 2 Immunoassay Analyzers. This assay can report results in =40 minutes using a serum or plasma sample volume of just 50 µL or less with no duplicate retesting. This study aims to evaluate the analytical and clinical performance of this assay. Methods Imprecision and reproducibility studies were conducted in accordance with CLSI EP05-A3 on both DxI 9000 and Access 2 analyzers. Imprecision was evaluated in a 20-day, 2 runs/day, 2 replicates/run study on serum and plasma samples with three reagent lots. Reproducibility was evaluated at 3 US clinical laboratories with serum and quality control samples (n=360 reps per sample) on three reagent lots. Cross-reactivity was evaluated using 337 specimens from 35 potential cross-reactant categories from individuals with conditions unrelated to syphilis infection (e.g., infections, auto-immunity, rheumatoid factor). The clinical performance on the DxI 9000 and Access 2 analyzers was evaluated at three U.S clinical laboratories. The performance of the Access Syphilis assay was compared to a final comparator result obtained using a composite algorithm of results from commercially available syphilis assays: the Abbott Architect Syphilis TP assay, a non-treponemal assay (Becton Dickenson Macro-Vue Rapid Plasma Reagin RPR Card), and a second treponemal assay (Fujirebio Inc. Serodia Treponema pallidum Particle Agglutination TP-PA). Results For positive samples, imprecision of 9% and 8% and reproducibility of 6% and 9% on Access 2 and DxI 9000, respectively, were observed. For negative samples, imprecision of 0.041 and 0.075 SD and reproducibility of 0.035 and 0.052 SD on Access 2 and DxI 9000, respectively, were observed. No cross-reactivity was observed on either platform for any sample/condition. The clinical study results demonstrated a positive percent agreement (PPA) of 100% for the Access Syphilis assay (n=184; 95% CI: 98-100%) and a negative percent agreement (NPA) of 96.7% (n=920; 95% CI: 95.4-97.7%) in the intended use population on both platforms. Conclusion The newly developed Access Syphilis assay for the DxI 9000 and Access 2 Immunoassay Analyzers has shown excellent analytical and clinical performance consistent with currently marketed syphilis assays. *FDA cleared in the US, not yet available for in vitro diagnostic use in all countries IVD: In Vitro Diagnostic Products. These products are labeled "For In Vitro Diagnostic Use."