Comparative assessment of veneral disease research laboratory (VDRL) and point of care (POC) tests for diagnosing syphilis among pregnant women at a tertiary health facility in Lagos: A retrospective cohort study

Abstract

Background: Syphilis is a systemic infection caused by the Spirochete Treponema Pallidum. The infection is of particular concern during pregnancy because of the high risk of vertical transmission causing adverse outcome including death. Traditional screening method is with Venereal Disease Research Laboratory (VDRL), which has a high false positive result and an increased waiting time. Aim: To compare the syphilis detection rate between Point-of-Care testing and Venereal Disease Research Laboratory testing among pregnant women. Methods: The retrospective cohort study was conducted at 68 Nigerian Army Reference Hospital Yaba (68NARHY), Lagos between July 2021 and June 2023. Data from antenatal clinic records were retrieved. All eligible pregnant women had both POC and VDRL testing. The primary outcome measures were false positive, false negative, true positive, true negative of the two tests. The sensitivity, and specificity and the diagnostic accuracy of both tests were calculated following which the ROC curve was drawn. Women with incomplete record or who did not conduct both testing were excluded from the study. All data set were collected using a well-designed purpose driven proforma. The data set were stored and later analyzed using the IBM SPSS for Windows, version 26.0 Armonk, NY: IBM corp. Analysis was both descriptive and inferential. The p-value of < 0.05 was set as statistically significant levels. Result: The mean age of the participants was 31.30±5.3. About 45.5% were of low parity while military personnel consisted of more than half of the study population. The prevalence of syphilis was 1.8% and 4.3% using VDRL and POC test kits respectively. When compared, there was a significant difference (P<0.001). It was also noted that a greater proportion of military personnel were reactive to the screening using either of those kits as against civilians. Conclusion: In our study, POC has demonstrated its ability to detect more cases of syphilis than VDRL as a screening test. Therefore, POC may serve as a cost-effective replacement screening test for VDRL, to rapidly and accurately detect syphilis infection. This step is crucial for early diagnosis, prompt treatment, and the prevention of further transmission of syphilis.