Rapid plasma reagin titer variation in the 2 weeks after syphilis therapy.
BACKGROUND
Serologic tests for syphilis results at the time of diagnosis are the basis for evaluating response to syphilis therapy. After treatment, however, serologic tests for syphilis titers may continue to increase for several weeks. We evaluated rapid plasma reagin (RPR) titer variation during the 14 days after therapy using data from a recent large, prospective randomized controlled trial.


METHODS
Prospectively enrolled participants in North America and Madagascar with primary, secondary, or early latent syphilis were randomly assigned to penicillin, doxycycline (in the case of penicillin allergy), or azithromycin treatment. Blood for RPR analysis was drawn at days 0, 7, and 14 posttreatment. All RPR titers were determined simultaneously at a central laboratory.


RESULTS
Four hundred and seventy patients had data available for at least 2 of 3 RPR measurements. Overall, 20% of patients showed a titer increase of at least 1 dilution in the 14 days after therapy. The greatest proportion of titer increases following therapy was observed in patients with primary syphilis. Comparing outcome of therapy using the initial (day 0) RPR titer versus the maximal RPR titer (during 14 days) resulted in outcome reclassification in 2.98% of participants.


CONCLUSIONS
Despite the fact that about 20% of early syphilis patients had increases in RPR titers immediately after treatment, these changes rarely influenced assessment of therapeutic outcome. Only 3% of patients treated would have been reclassified.
Department of Quality Management, Birmingham VA Medical Center, Birmingham, AL 35294, USA.
Katherine M
KM
Holman
Mark
M
Wolff
Arlene C
AC
Seña
David H
DH
Martin
Frieda
F
Behets
Kathleen
K
Van Damme
Peter
P
Leone
Linda
L
McNeil
Meredyth L
ML
Gehrig
Edward W
EW
Hook
D000328:Adult; D000704:Analysis of Variance; D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D000907:Antibodies, Bacterial / Q000097:blood; D017963:Azithromycin / Q000008:administration & dosage*; D004318:Doxycycline / Q000008:administration & dosage*; D004334:Drug Administration Schedule; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D007155:Immunologic Factors / Q000097:blood; D008270:Madagascar / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009656:North America / Q000453:epidemiology; D010406:Penicillins / Q000008:administration & dosage*; D011446:Prospective Studies; D011935:Reagins / Q000097:blood*; D013587:Syphilis / Q000097:blood* / Q000188:drug therapy*; D013588:Syphilis Serodiagnosis / Q000379:methods*; D013997:Time Factors; D016896:Treatment Outcome; D014210:Treponema pallidum / Q000276:immunology / Q000302:isolation & purification*; D055815:Young Adult
D000900:Anti-Bacterial Agents; D000907:Antibodies, Bacterial; D007155:Immunologic Factors; D010406:Penicillins; D011935:Reagins; D017963:Azithromycin; D004318:Doxycycline