Evaluation of the Diagnostic Algorithms for Serodiagnosis of Syphilis

We analyzed the performance parameters of the traditional and reverse algorithms to determine which is more convenient for serodiagnosis of syphilis. In total, 4,789 serum samples were obtained from a cross-sectional study. Venereal Disease Research Laboratory (VDRL), Treponema pallidum hemagglutination assay (TPHA), and chemiluminescent microparticle immunoassay (CMIA) tests were performed on each serum sample. In case of discordance between results, TPHA was applied as a second treponemal test. Overall, 207 patients were serodiagnosed with syphilis. Among the 4,789 samples tested, 125 (2.6%) and 206 (4.3%) were positive using the traditional and reverse algorithms, respectively. The missed diagnosis rate of the traditional algorithm was 42.5%. The reverse algorithm had a higher sensitivity than that of the traditional algorithm. The sensitivity levels of the traditional and reverse algorithms were 57.49% and 99.85% respectively. The false positivity rate of the reverse algorithm was 0.02%.