Rapid Syphilis Testing for Men Who Have Sex with Men in Outreach Settings: Evaluation of Test Performance and Impact on Time to Treatment

Abstract

Rapid syphilis tests (RST) may shorten time to syphilis diagnosis and treatment while enhancing access to testing in outreach settings. There are limited data on the performance of RST in outreach settings in the US. Methods We offered RST (Syphilis Health Check) at 6 outreach sites to men who reported having sex with men and no prior history of syphilis. Clients accepting RST were also tested with laboratory-based rapid plasma reagin (RPR) and reflex Treponema pallidum particle agglutination (TPPA) assay when RPR or RST were positive. Clients with positive RST were immediately referred to a sexually transmitted infection clinic. Those declining RST were screened with RPR and reflex TPPA only. The validity of the RST-based algorithm was compared with the RPR-based algorithm among participants receiving both. Time to treatment for those accepting RST was compared with those declining RST and to a historical control group screened in outreach settings with RPR and reflex TPPA before the availability of RST. Results Rapid syphilis test was accepted by 690 (64%) of 1081 eligible clients. Compared with RPR-based algorithm, RST sensitivity was 90%; specificity, 98.5%; positive predictive value, 47.4%; and negative predictive value, 98.5. The single false-negative case by RST was determined to be a late latent case by RPR/TPPA. Median time to treatment was 1 day (range, 0-6 days) for 9 of 690 accepting RST, compared to 9 days (range, 7-13 days) for 3 of 391 declining RST, and 9 days (range, 6-21 days) for 25 of 1229 historical controls (P < 0.0001). Conclusion Compared with an RPR-based algorithm, RST identified all early syphilis cases. Although RST had high specificity and negative predictive value, the low positive predictive value resulted in additional assessments in a sexually transmitted infection clinic for some patients. However, RST use in outreach settings significantly decreased time to treatment for new syphilis cases.