Fig. 1.

Distribution of CIA signal/cutoff values in different serum groups. (A) Signal/cutoff value distribution in CIA⁺TPPA⁻RPR⁻ (n = 478), CIA⁺TPPA⁺RPR⁻ (n = 1034) and CIA⁺TPPA⁺RPR⁺ (n = 791) groups. (B) RPR titers versus signal/cutoff values in CIA⁺TPPA⁺RPR⁺ sera. +, reactive; −, nonreactive; RPR (titer, 1:1), n = 477; RPR (titer, 1:2), n = 128; RPR (titer, 1:4), n = 76; RPR (titer, 1:8), n = 33; RPR (titer, 1:16), n = 34; RPR (titer, 1:32), n = 19; RPR (titer, > 1:32), n = 24. Abbreviations: CIA, chemiluminescence immunoassay; TPPA, Treponema pallidum particle agglutination assay; RPR, rapid plasma reagin test