Correlation of Treponemal Immunoassay Signal Strength Values With Reactivity of Confirmatory Treponemal Testing.

4 years ago

Correlation of Treponemal Immunoassay Signal Strength Values With Reactivity of Confirmatory Treponemal Testing.

Jeff M Schapiro, Anthony Tran, Yetunde F Fakile, Kathleen J Gustafson, Susan M Novak-Weekley, Ina U Park, Joan M Chow, Heather Jost, Karen W Hoover

Automated treponemal immunoassays are used for syphilis screening with the reverse sequence algorithm; discordant results (e.g., enzyme immunoassay [EIA]-reactive, reactive plasma reagin [RPR]-non-reactive) are resolved with a second treponemal test. We conducted a study to determine automated immunoassay signal strength values consistently correlating with reactive confirmatory treponemal testing.We conducted a cross-sectional analysis of four automated immunoassays: BioPlex 2200 microbead immunoassay (MBIA), LIAISON chemiluminesence immunoassay (CIA), ADVIA-Centaur CIA, and TrepSure EIA, and three manual assays: Treponema Pallidum Particle Agglutination (TP-PA), Fluorescent Treponemal Antibody-Absorption (FTA-ABS) test, INNO-LIA line immunoassay. We compared signal strength values of automated immunoassays and positive and negative agreement. Among 1995 specimens, 908 (45.5%) were true positives (≥4/7 tests reactive) and 1087 (54.5%) were true negatives (≥4/7 tests non-reactive). Positive agreement ranged from 86.1% (83.7-88.2%) for FTA-ABS to 99.7% (99.0-99.9%) for ADVIA-Centaur CIA; negative agreement ranged from 86.3% (84.1-88.2%) for TrepSure EIA to 100% for TP-PA (99.6-100%). Increasing signal strength values correlated with increasing reactivity of confirmatory testing (ptrend <0.0001 for all automated immunoassay). All automated immunoassays had signal strength cutoffs corresponding to ≥4/7 reactive treponemal tests. Bioplex MBIA and LIAISON CIA had signal strength cutoffs correlating with ≥99% and 100% TP-PA reactivity, respectively. ADVIA-Centaur CIA and TrepSure EIA had signal strength cutoffs correlating with at least 95%TP-PA reactivity. All automated immunoassays had signal strength cutoffs correlating with at least 95% FTA-ABS reactivity. Assuming that a 95% level of confirmation is adequate, these signal strength values can be used in lieu of confirmatory testing with TP-PA and FTA-ABS.

Publisher URL: http://doi.org/10.1128/JCM.01165-17

DOI: 10.1128/JCM.01165-17