Table 1. Comparison of the reverse and traditional algorithms.

	Reverse algorithm, ASTP screen/RPR/TP-PA (95% CI)	Traditional algorithm, RPR screen/EIA/TP-PA (95% CI)
Positive syphilis cases, N = 59	58/59 98.3% (95.0–100%)	43*/59 72.9% (61.7–84.1%)
No laboratory evidence of syphilis, N = 1,020	1,020/1,020 100% (99.7–100%)	1,017/1,020 99.7% (99.3–100%)

^*Of the 16 nonreactive RPR results reported as negative for syphilis per the traditional algorithm, 11 (68.8%) were classified as P&S infections and five (31.2%) as past syphilis (with documented linkage to care), using the reverse algorithm.

Abbreviations: P&S, primary and secondary; RPR, rapid plasma reagin; ASTP, Abbott Architect Syphilis TP; TP-PA, Treponema pallidum particle agglutination; EIA, enzyme immunoassay; CI, confidence interval.