Enzyme‐linked immunosorbent assay ( ELISA ) versus Venereal Disease Research Laboratory test ( VDRL ) and rapid plasma reagin test ( RPR ) for screening of syphilis in pregnant women

Objective To evaluate a treponemal enzyme‐linked immunosorbent assay ( ELISA ) as an alternative screening test for syphilis in pregnant women. Methods A cross‐sectional study of diagnostic test accuracy was carried out in a large volume laboratory from a tertiary care center. A total of 416 serum samples, including 102 archived syphilis Treponema pallidum hemagglutination ( TPHA )‐positive samples and 314 samples from pregnant women, were used to determine the sensitivity and specificity of ELISA . All the samples were subjected to Venereal Disease Research Laboratory ( VDRL ), rapid plasma reagin ( RPR ), ELISA , and TPHA tests. Performance characteristics of VDRL , RPR , and ELISA were calculated with TPHA as a reference standard test. Results VDRL and RPR exhibited higher false positivity of 10.5% and 9.6%, respectively, compared to 2.5% by ELISA . The sensitivity and specificity of ELISA were 98% and 97.5%, of VDRL were 71.6% and 89.5%, and of RPR were 73.5% and 90.5%, respectively. Moreover, ELISA had an excellent agreement (kappa=0.9) with TPHA compared to VDRL / RPR which had a moderate agreement (kappa=0.6) only. Conclusion ELISA has the potential to replace VDRL / RPR as a screening test for syphilis in centers that can perform ELISA , especially for antenatal screening.