An evaluation of on-site testing for syphilis

One of the major obstacles to the eradication of perinatal transmission of syphilis is the delay in obtaining the results of syphilis serological tests. The availability of on-site syphilis testing lead to this study which attempted to evaluate on-site syphilis testing performed by nursing staff. The seroprevalence of syphilis by laboratory rapid plasma reagin (RPR) was 8.2% (n=42). Twenty-one of the 42 women were correctly identified by the on-site test. The overall sensitivity of on-site testing was 50% [95% confidence interval (CI)=34.4-65.6]; specificity of 90.9% (95% CI=87.8-93.2). The on-site test correctly identified as uninfected 429 of the 471 women reported as RPR negative by the laboratory, giving a specificity of 91.1% (95% CI=88.1-93.4). The results of the study show that on-site RPR test had a sensitivity of 75% in respect of the clinically important titres of > or = 1:8. The specificity of the on-site test was 91.1% and on-site testing only failed to detect syphilis in those patients with titres of 1:1 and 1:2. On-site testing is a practical and cost-effective option to prevent congenital syphilis, in settings of a high prevalence of syphilis and using skilled testers.