Utility of the Syphilis Health Check™ in an STD Clinic Setting

Background: Syphilis Health Check™ (SHC) is the first CLIA waived rapid syphilis test (RST) in the US.  Whether a treponemal specific RST improves syphilis diagnosis and management in an STD clinic is unknown.

Methods:  As a pilot at San Francisco City Clinic, the SHC was used in patients with no known prior history of syphilis to guide clinical management in the following scenarios: 1) Diagnostic evaluation of oral or anogenital lesion(s); 2) Confirmation of positive non-treponemal test; 3) Contact to syphilis.  A stat RPR and lab based VDRL and TPPA were also obtained as per clinic protocols.  Final determination of syphilis disease status (positive, negative or indeterminate) was based on serologic results and clinical findings.    

Results:  From 9/15-1/16, 29 patients were tested with the SHC; 28 were male and 24 were MSM.  20 patients had oral or anogenital lesions, 1 had a weakly reactive VDRL with a pending TPPA, 7 were contacts to syphilis and in 1 reason for testing was unknown.  Overall, 5 patients had a positive SHC.   Of these, 1 had early latent syphilis, 2 were false positives and 2 were indeterminate.  One of the indeterminate cases had a tongue lesion, a weakly reactive VDRL and stat RPR, and a negative TPPA.  The other had a penile lesion, but VDRL, stat RPR and TPPA were negative.  There was one false negative SHC in a patient with primary syphilis who had a perianal lesion, positive stat RPR and TPPA, and a VDRL of 1:4.  

Conclusions:  In this small pilot in an STD clinic, 40% of SHC’s were false positives, and the SHC missed one of two patients with true disease.  Over-reading of a faintly positive test line may have contributed to the high false positive rate.  The SHC did help rule-out syphilis in several symptomatic patients who otherwise may have been empirically treated with penicillin.