Ann Lab Med.  2017 Nov;37(6):511-515. 10.3343/alm.2017.37.6.511.

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

• Nah EH
• Cho S
• Kim S
• Cho HI
• Chai JY

• KMID: 2425992
• DOI: http://doi.org/10.3343/alm.2017.37.6.511

Abstract

BACKGROUND
The 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.
METHODS
In 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).
RESULTS
Of 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).
CONCLUSIONS
The 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.

Keyword

Syphilis; Treponema pallidum; Rapid plasma regain (RPR); Treponema pallidum latex agglutination; Chemiluminescent microparticle immunoassay; Algorithm

MeSH Terms

Agglutination
Automation
Budgets
Epidemiology
Female
Humans
Immunoassay
Latex
Male
Mass Screening*
Plasma
Syphilis*
Syphilis, Latent
Treponema pallidum
Latex

Figure

• 

  Fig. 1 Traditional and Reverse algorithms for syphilis diagnosis.Abbreviations: TPLA, Treponema pallidum latex agglutination; RPR, rapid plasma regain; CMIA, chemiluminescent microparticle immunoassay.

• 

  Fig. 2 Comparison of the quantitative results of TPLA between true reactive TPLA [TPLA(+)/RPR(-)/CMIA(+)] and false reactive TPLA [TPLA(+)/RPR(-)/CMIA(-)] cases in the reverse algorithm. Dotted line represents the cutoff index of TPLA test.Abbreviations: TPLA, Treponema pallidum latex agglutination; RPR, rapid plasma regain; CMIA, chemiluminescent microparticle immunoassay.

• 

  Fig. 3 Area under the receiver operator curve of TPLA for syphilis screening.Abbreviation: TPLA, Treponema pallidum latex agglutination.

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