Analysis of reactivity pattern of venereal disease research laboratory test in a tertiary care hospital

Abstract

Background: In India, sexually transmitted diseases are one of the major risk factors for acquisition of HIV and infertility. Most of the sexually transmitted diseases are asymptomatic and we rely on cytology, culture, serological evidence and sexual history to diagnose them. VDRL and TPHA are the two most important serological tests in the diagnosis of syphilis. Aim of the study was analysis of quantitative VDRL reactivity pattern and the prevalence of false positive VDRL. Methods: 7543 patient records were taken. Age, gender, and referral status were recorded. Total records of study population were divided into 2 groups. Group 1-true positive-both VDRL and TPHA Positive. Group II-False positive-VDRL positive and TPHA negative. Results: Among 7543 cases the ratio of True positive: false positive = 84:16 and in both groups males outnumbered females. In both groups, low titer VDRL took 70%. 61% of false positive cases were in the older age group. Conclusions: True positives were seen mainly in younger sexually active age group with majority having low titer VDRL (Less than 1:8) emphasizing the need for creating awareness of STDs among this age group and the need for early interventions.Keywords: Biological false positive VDRL, TPHA, VDRL DOI: http://dx.doi.org/10.18203/2320-6012.ijrms20173549Prabahar P et al. Int J Res Med Sci. 2017 Aug;5(8):3498-3501 International Journal of Research in Medical Sciences | August 2017 | Vol 5 | Issue 8 Page 3499 7543 cases were tested for syphilis with VDRL and TPHA. Out of 7543 cases, 4599 were males and 2944 were females. The patients were grouped into (1) patients who came for screening without any complaints, (2) patients referred from other specialties and other hospitals (government and private), and (3) Partner screening.Out of 7543 cases 128 became VDRL reactive (1.7%). All the VDRL reactive cases were tested for TPHA. Among the VDRL reactive cases 110 became positive for TPHA (85.9%) and 18 cases were TPHA negative (14.1%). Out of the 110 cases, VDRL titer was >1: 8 in 37 whereas VDRL was <1: 8 in 73. Only in 3 cases, VDRL titer was high (1: 126). The remaining 18 cases were TPHA negative and diagnosed as biological false positive cases. Lab ProcedureIn above subject groups, Syphilis screening was done by VDRL test. VDRL reactive serum again underwent serial dilution for quantitative analysis. VDRL reactive serum was again tested for TPHA to rule out false positive VDRL. VDRL non-reactive patients were advised to repeat the test after 3 months with sexual abstinence or protected sex. RESULTSIn this study 7543 patients were screened with VDRL test and 128 (1.7%) turned out to be reactive. VDRL reactivity was higher in male patients (2.3%) as compared with females (0.75%) as shown in Table 1. Patients were grouped as true positive (Group I) who were both VDRL and TPHA positive, and false positive (Group II) who were VDRL positive and TPHA negative. Table 2 shows quantitative VDRL results based on gender and age group in true positives and false positives. 1.46% ...