Ann Lab Med.  2019 Jul;39(4):396-399. 10.3343/alm.2019.39.4.396.

Comparative Performance of the Reverse Algorithm Using Architect Syphilis TP Versus the Traditional Algorithm Using Rapid Plasma Reagin in Florida's Public Health Testing Population

• Totten YR
• Hardy BM
• Bennett B
• Rowlinson
• Crowe S

• KMID: 2438887
• DOI: http://doi.org/10.3343/alm.2019.39.4.396

Abstract

In Florida, where syphilis is a reportable disease, the number of primary and secondary (P&S) syphilis cases has increased from 3,266 in 2008-2010 to 5,340 in 2013-2015, a 63% increase. The objective of this study was to compare the performance and sensitivity of the syphilis reverse algorithm with the traditional algorithm for detecting P&S (infectious) syphilis cases. Clinical specimens from individuals who self-referred for syphilis testing at public health clinics were processed using the traditional algorithm (non-treponemal rapid plasma reagin (RPR) test followed by a confirmatory treponemal (EIA) test) and then further tested with the Architect Syphilis TP (ASTP) immunoassay (Abbott Diagnostics, Chicago, IL, USA) or by RPR confirmation, if needed (reverse algorithm). Of 1,079 specimens, 59 were positive for syphilis. The sensitivity of the reverse algorithm was 98.3% (58/59) and of the traditional algorithm was 72.9% (43/59). Based on clinical evidence, of the 16 traditional algorithm-negative but reverse algorithm-positive cases, 68.8% (11/16) were classified as missed P&S infections (treatment naïve) and 31.2% (5/16) were classified as missed past syphilis (latent or infections with documented linkage to care). The reverse algorithm enables the detection of additional P&S syphilis cases missed by our current traditional algorithm.

Keyword

Syphilis; Traditional algorithm; Reverse algorithm; Detection; Architect Syphilis TP; Rapid plasma reagin; Florida

MeSH Terms

Florida
Immunoassay
Plasma*
Public Health*
Syphilis*

Figure

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  Fig. 1 Reverse and traditional algorithm schematics with testing population distribution.*Based on the PRISM review of the 42 positive syphilis cases common to both algorithms, only 11 were reported as P&S (infectious) cases; †Clinical evaluation should be performed to identify signs, symptoms, or history of infection; ‡Syphilis staging as per PRISM review.Abbreviations: P&S, primary and secondary; RPR, rapid plasma reagin; ASTP, Abbott Architect Syphilis TP; TP-PA, Treponema pallidum particle agglutination; EIA, enzyme immunoassay; CMIA, chemiluminescence microparticle immunoassay.

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