Clinical Evaluation of a New Chemiluminescence Assay for the Detection of Treponema Pallidum Antibodies

Background: A new chemiluminescence assay, the Anti-TP-II assay, is going to be commercially available in clinical laboratories in China and other countries. This study examined the performance of the new assay for the detection of TP infection and compared it with that of the Anti-TP assay by using large amounts of clinical samples. Methods: The precision, accuracy, anti-interference ability, and the clinical sensitivity and specificity of the AntiTP-II assay were evaluated. In addition, compared with those of the Anti-TP assay, the false positive and false negative rates of the Anti-TP-II assay were evaluated for 2,436 clinical routine samples and 711 preselected AntiTP assay reactive samples. Discrepancy of the samples was investigated with the recomLinec Treponema IgM/IgG kit or the Elecsys syphilis assay. Results: The precision, accuracy, and anti-interference ability of the Anti-TP-II assay met the national standard of China, and there was an overall agreement of 96.75% (Kappa = 0.91) between the two assays. The sensitivity and specificity of the Anti-TP-II assay were 100% (95% CI: 94.13% to 100%) and 99.92% (95% CI: 99.70% to 99.99%), respectively. Compared with the Anti-TP assay, the Anti-TP-II assay significantly reduced the number of borderline samples and the false positive rate. Conclusions: Considering its excellent performance, the Anti-TP-II assay is a good screening test for high-throughput laboratories and can replace the previous generation of reagents, the Anti-TP assay, with a superior specificity.