(P98) PERFORMANCE AND USABILITY OF TWO FDA-APPROVED RAPID DIAGNOSTIC TESTS FOR SYPHILIS

Background:
Incidence of syphilis, a sexually and perinatally transmitted infection caused by Treponema pallidum, has increased in recent decades. Prompt diagnosis and treatment of this curable infection reduces associated morbidity. New CDC guidelines for screening and/or diagnosis of syphilis include the use of point-of-care rapid treponemal antibody tests. We reviewed the performance and usability for two FDA-approved, CLIA-waived, treponemal antibody, rapid diagnostic tests.

Methods:
We reviewed FDA pre-marketing approval documents and searched PubMed for reports presenting the performance of the Syphilis Health Check (Diagnostics Direct, LLC Stone Harbor, NJ) or the DPP HIV-Syphilis System (Chembio Diagnostic Systems, Inc Medford, NY). Systematic reviews, secondary reports referencing primary studies, and those not reporting performance metrics were excluded from analysis. Data about specimen type, population, reference test, and usability were also collected to allow further analysis. Pooled sensitivity and specificity with 95% confidence intervals were calculated based on reported positive and negative test results in comparison to a reference standard.

Results:
7 reports for Syphilis Health Check and 6 reports for DPP HIV-Syphilis System and their respective FDA-approved package inserts were included. Syphilis Health Check’s pooled sensitivity and specificity were 88.8% (95% CI: 87.0-90.6%) and 96.0% (95% CI: 94.0-97.9%) respectively among 9061 tests; DPP HIV-Syphilis System’s pooled sensitivity and specificity were 85.7% (95% CI: 83.9-87.9%) and 98.0% (95% CI: 95.9-100%) among 8491 tests.

The DPP HIV-Syphilis System is more expensive (>$15/test vs. $10/test for the Syphilis Health Check) with longer time to result (15 minutes vs. 10 minutes), but advantages included a smaller volume blood specimen (10µl vs. 50µl), and concurrent HIV antibody detection. Additionally, DPP HIV-Syphilis System requires a DPP Micro Reader for result interpretation, which may increase complexity, but reduce risk of human error.

Conclusion:
Test performance appears similar between both rapid treponemal antibody tests while usability varies depending on testing sites’ needs and priorities.