Sensitivity and specificity of ELISA combined with TPPA for diagnosis of syphilis

Objective To investigate the value of Enzyme Linked Immunosorbent Assay (ELISA) combined with Treponema Pallidum Particle Agglutination assay (TPPA) in the detection of syphilis. Methods Seventy patients with suspected syphilis admitted to our hospital from January, 2018 to January, 2019 were enrolled. All the patients’ serum samples were tested by ELISA and TPPA. The serotonin from lymph node puncture was used as the gold standard. The diagnostic results by these two methods and by the combination, such as diagnostic accuracy, specificity, sensitivity, and positive and negative predictive values, were compared. Results Lymph node aspiration tests showed that among the 70 cases, 50 got syphilis; 47 of the 70 suspected syphilis patients were tested by ELISA; 47 of the 70 suspected syphilis patients were tested by TPPA ; and the combined ELISA and TPPA testing showed that 49 had syphilis. The accuracy, sensitivity, specificity, and negative predictive value of the combined ELISA and TPPA tests were higher than those of ELISA and those of TPPA , with statistical differences (all P< 0.005). The positive predictive value of the combination of ELISA and TPPA was higher than that of ELISA, with a statistical difference (χ2=4.696, P=0.012). Conclusion The combination of ELISA and TPPA has a high application value in the diagnosis of syphilis, and can improve the accuracy, sensitivity, specificity, and positive and negative predictive values. It is worthy of further clinical application. Key words: Syphilis; Enzyme-linked immunosorbent assay; Gelatin particle agglutination test; Accuracy; Sensitivity