Comparison of Traditional and Reverse Syphilis Screening Algorithms in Medical Health Checkups

Abstract

BackgroundThe syphilis diagnostic algorithms applied in different countries vary significantly depending on the local syphilis epidemiology and other considerations, including the expected workload, the need for automation in the laboratory and budget factors. This study was performed to investigate the efficacy of traditional and reverse syphilis diagnostic algorithms during general health checkups.MethodsIn total, 1,000 blood specimens were obtained from 908 men and 92 women during their regular health checkups. Traditional screening and reverse screening were applied to the same specimens using automatic rapid plasma regain (RPR) and Treponema pallidum latex agglutination (TPLA) tests, respectively. Specimens that were reverse algorithm (TPLA) reactive, were subjected to a second treponemal test performed by using the chemiluminescent microparticle immunoassay (CMIA).ResultsOf the 1,000 specimens tested, 68 (6.8%) were reactive by reverse screening (TPLA) compared with 11 (1.1%) by traditional screening (RPR). The traditional algorithm failed to detect 48 specimens [TPLA(+)/RPR(−)/CMIA(+)]. The median TPLA cutoff index (COI) was higher in CMIA-reactive cases than in CMIA-nonreactive cases (90.5 vs 12.5 U).ConclusionsThe reverse screening algorithm could detect the subjects with possible latent syphilis who were not detected by the traditional algorithm. Those individuals could be provided with opportunities for evaluating syphilis during their health checkups. The COI values of the initial TPLA test may be helpful in excluding false-positive TPLA test results in the reverse algorithm.

Evaluation of the Elecsys Syphilis electrochemiluminescence immunoassay as a first-line screening test in the reverse algorithms for syphilis serodiagnosis

“…The reverse algorithm revealed 158 (3.3%) subjects with discordant results in this study. Nah et al classified the discordant cases with positive treponemal and negative non-treponemal tests into two groups by the second treponemal test results, and reported that the second treponemal test-positive group tended to be older (Nah et al, 2017). However, there were no significant differences in age among the three groups according to the second treponemal test results in our study.…”

“…This study indicated that the seroprevalence (4.2%) of the reverse syphilis algorithm was higher than that (1.1%) of the traditional algorithm. Nah et al reported seroprevalences of 5.4% and 0.6% for the reverse and traditional algorithms, while Huh et al reported very low seroprevalence of 0.6% and 0.1%, respectively (Huh et al, 2016;Nah et al, 2017). Both studies included subjects undergoing routine health checkups, but they showed different seroprevalences.…”

“…In this study, the corresponding k value between the traditional and reverse algorithm was 0.415, which indicated moderate agreement. The other study reported a k value of only 0.191, indicating a poor agreement in the routine health checkup setting (Nah et al, 2017), while a study in China reported a k value of 0.668 in HIV-infected individuals (Chen et al, 2017). These differences may contribute to the different screening methods in each algorithm, characteristics of subjects, and distribution of syphilis stages.…”

“…Reverse missed-diagnosis rate than the reverse or ECDC algorithms (Binnicker et al, 2012;Dunseth et al, 2017;Huh et al, 2016;Mishra et al, 2011;Nah et al, 2017). Tong et al evaluated the algorithms using clinical diagnosis as a gold standard, and reported a sensitivity of 75.81% and a missed-diagnosis rate of 24.19% by the traditional algorithm in a population with high syphilis prevalence of 11.4%, while the reverse and ECDC algorithms had higher sensitivities of 99.38%-99.85% when compared to the traditional algorithm (Tong et al, 2014).…”

Evaluation of RPR, TPHA test results and diagnostic algorithms used in syphilis diagnosis

“…'nın (16) da rapor ettiği gibi geçirilmiş veya son zamanlarda tedavi almış hastalarda ve ayrıca hastalığın geç/latent dönemlerinde de görülebileceği düşünülmüştür. Bulgularımızla benzer olarak farklı çalışmalarda da belirtildiği gibi, tarama amacıyla nontreponemal testlerin yerine treponemal testlerin kullanılmasının pozitifliklerde artışa neden olduğu görülmüştür (18)(19)(20) . Çalışmamızda, konvansiyonel algoritma ile %3.35, ters algoritma ile %2.81 yalancı pozitiflik belirlenmiştir.…”