Background: Increasingly, clinical laboratories screen for syphilis with a treponemal test (Treponema pallidum EIA; TpEIA), and if positive, RPR testing is done. This algorithm identifies TpEIA+/RPR non-reactive (-) persons who would not be identified by traditional RPR screening algorithms. A confirmatory treponemal test (FTA) is then done. Persons who are FTA+ are considered to have “evidence of past treated or untreated syphilis”, but the clinical implications of these test results are unclear.
Objectives: To help understand the meaning of these test results by reviewing medical records from TpEIA+/RPR- persons.
Methods: We reviewed medical records from patients with TpEIA+/RPR- at a
Results: 404 patients had 511 TpEIA+/RPR-results. A random sample of 150 records were sought, 128 (85%) reviewed. 121 were FTA+, 6 FTA-, 1 had no FTA. Median age was 46 (range 21-93); 55% were male. Most were HIV-positive (male 70%;49/70, female 66%;38/58) or HIV-status unknown (15%;19/128). Common screening reasons were: routine screening among HIV+ patients (52%; 66/128); psychiatric screening (18%;23/128). Almost half (47%; 60/128) had previous syphilis (80% were HIV-positive), 33% (42/128) had previous syphilis treatment (76% HIV-positive), and 34% (43/128) had previous reactive RPRs (88% HIV-positive). Only 2 patients were documented to have no previous reactive RPR, no syphilis history, nor treatment, however, 56 were missing information on >1 of these variables. Physicians considered 9/128 (7%) to have late latent syphilis, (3 HIV-positive, 2 HIV-negative, 4 unknown).
Conclusions: In this hospital, most TpEIA+/RPR- patients were HIV-infected and had past syphilis. There appear to be few untreated cases, but further evaluation/investigation is needed.
Implications for Programs, Policy, and/or Research: Additional investigations, including some of low risk populations (eg pregnant women), are needed to clarify the clinical implications of Tp-EIA+/RPR- results.