Superior Detection of Syphilis With the Rapid Test DETERMINE Compared With Combined Cardiolipin- and Treponemal-Specific Tests

Objective: The aim of the studywas to quantify detection of syphilis with the DETERMINE Syphilis test versus single or combined treponemal/cardiolipin tests in a primary care setting. Methods: A total of 107 positive DETERMINE results obtained in 1898 samples were compared with combined Rapid Plasma Reagin/ Venereal Disease Research Laboratory and Fluorescent Treponemal Antibody Absorption results. True-positive tests were defined as either serological confirmation by either cardiolipin and/or specific treponemal positive results at diagnosis or at 1-week follow-up or signs and symptoms classically compatible with syphilis, which resolved completely and rapidly on administration of a single-dose benzathine penicillin G. All positive cases showed a sustained positive result in the DETERMINE Syphilis test at follow-up. False-positive tests with DETERMINE Syphilis test were defined as being unconfirmed by cardiolipin and specific treponemal positive tests at baseline and negativity in the follow-up period. Results: A total of 107 patients were positive with the DETERMINE Syphilis TP test. Of those, 20 (18.7%) were negative in both cardiolipin and specific treponemal positive tests. Fourteen (13.1%) were negative in cardiolipin tests but positive in specific treponemal positive tests. Of those patients with a positive DETERMINE Syphilis TP test result but with negative dual confirmation, 15 were shown to be true-positive results by fulfilling one or more of the aforementioned criteria, making this rapid syphilis test 14.0% superior in the diagnosis of syphilis than combined conventional tests. Compared with the use of single cardiolipin tests, the DETERMINE Syphilis TP test detected 29 more cases (27.1%). False-positive tests with DETERMINE Syphilis TP test occurred in 5 patients (0.26%) of all those tested. Conclusions: The DETERMINE Syphilis test is superior to treponemal and cardiolipin tests alone or in combination in the detection of syphilis in primary care.