Assessing the usefulness of antibody index values from treponemal immunoassays to reduce confirmatory syphilis testing in the reverse algorithm.

We assessed utility of antibody index values from treponemal immunoassays against confirmatory tests following reverse syphilis algorithm. We tested sera collected from a population at increased risk and established thresholds for treponemal immunoassays. High concordance with confirmatory tests was observed, indicating potential use of assay specific threshold to reduce testing.