Evaluation of a rapid syphilis test in an emergency department setting in Detroit, Michigan

BACKGROUND: Syphilis transmission can be prevented by prompt diagnosis and treatment of primary and secondary infection. We evaluated the performance of a point-of-care rapid syphilis treponemal test (RST) in an emergency department (ED) setting. METHODS: Between June 2015 and April 2016, men aged 18-34 years seeking services in a Detroit ED, and with no history of syphilis, were screened for syphilis with the RST, rapid plasma reagin (RPR) test, and Treponema pallidum particle agglutination assay (TP-PA). A positive reference standard was both a reactive RPR and a reactive TP-PA. We compared test results in self-reported MSM to non-MSM. RESULTS: Among 965 participants, 10.9% of RSTs were reactive in MSM and only 1.5% in non-MSM (p\u3c0.001). Sensitivity of the RST was 76.9% and specificity was 99.0% (PPV 50.0%) compared to the positive reference standard. Three discordant specimens found negative with the RST but positive with the reference standard had an RPR titer of 1:1, compared with 10 specimens with concordant positive results that had a median RPR titer of 1:16. The RST sensitivity was 50.0% (PPV 68.4%) compared to the TP-PA test alone. Among men seeking care in an ED, the RST detected 76.9% of participants with a reactive RPR and TP-PA. CONCLUSIONS: The RST detected all of the participants with an RPR titer \u3e 1:2 but less than 20% of participants with a positive TP-PA and negative RPR. The RST was useful to detect a high proportion of participants with an active syphilis in an urban ED. This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal