Clinical evaluation of four recombinant Treponema pallidum antigen-based rapid diagnostic tests for syphilis

To evaluate the sensitivity, specificity and feasibility of four rapid tests in the diagnosis of syphilis in sexually transmitted disease diagnosis and treatment centre of Peking Union Medical College Hospital.

Tests were performed on consecutive clinic attendees, using whole blood in the clinic, and whole blood and serum in the laboratory. The sensitivity and specificity of each test was evaluated, using a standard treponemal test (Treponema pallidum haemagglutination assay) as the gold standard.

The results are as follows. Abbott Determine Syphilis TP test: for serum specimens, the sensitivity was 100% and specificity was 98.9%; for whole blood specimens, the sensitivity was 81.9% and specificity was 99.4%. SD Bioline Syphilis 3.0 test: for serum specimens, the sensitivity was 95.5% and specificity was 97.9%; for whole blood specimens, the sensitivity was 87.6% and specificity was 99.4%. VisiTect-Syphilis test: for serum specimens, the sensitivity was 94.0% and specificity was 98.1%; for whole blood specimens, the sensitivity was 73.5% and specificity was 99.7%. Syphicheck-WB test: for serum specimens, the sensitivity was 67.4% and specificity was 98.8%; for whole blood specimens, the sensitivity was 64.0% and specificity was 99.7%.

We therefore strongly believe that rapid serological tests for syphilis are an acceptable alternative to conventional laboratory tests. Since they do not require equipment or electricity, they could increase coverage of syphilis screening, and enable treatment to be given at the first clinic visit.