Association of hepatitis C virus infection with false-positive tests for syphilis.
The prevalence of false-positive reactions for syphilis (reactive rapid plasma reagin [RPR] test and nonreactive fluorescent treponemal antibody absorption [FTA-ABS] test) among patients at sexually transmitted disease (STD) clinics was assessed to evaluate the association between false-positive RPR reactions and hepatitis C virus (HCV) infections. Among 2672 patients, 400 (15.0%) had antibodies to HCV (anti-HCV) and 254 (9.5%) had a reactive RPR test. Of the 254 reactive RPR tests, 231 (90.1%) were also positive by FTA-ABS, leaving 23 false-positive RPR reactions. After excluding the 231 patients with positive FTA-ABS tests, false-positive RPR tests were found in 9 (2.7%) of 330 anti-HCV-positive patients compared with 14 (0.6%) of 2154 anti-HCV-negative participants (relative risk, 4.5; 95% confidence interval, 1.9-10.9; P = .0017). These data demonstrate that HCV infection is associated with false-positive RPR test results. However, because of the high prevalence of syphilis among STD patients, the RPR test remains a strong indicator of syphilis in this setting.
Thomas
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DL
Division of Infectious Diseases, Johns Hopkins University School of Medicine, Preventive Medicine and Epidemiology, Bethesda, Maryland 21205.
Rompalo
A M
AM
Zenilman
J
J
Hoover
D
D
Hook
E W
EW
Quinn
T C
TC
D000293:Adolescent; D000328:Adult; D000368:Aged; D000554:Ambulatory Care Facilities; D000907:Antibodies, Bacterial / Q000097:blood; D002648:Child; D005189:False Positive Reactions; D005260:Female; D006508:Hepatitis Antibodies / Q000097:blood; D006526:Hepatitis C / Q000150:complications / Q000276:immunology*; D018937:Hepatitis C Antibodies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011935:Reagins / Q000097:blood; D013587:Syphilis / Q000150:complications; D013588:Syphilis Serodiagnosis / Q000706:statistics & numerical data*; D014210:Treponema pallidum / Q000276:immunology
D000907:Antibodies, Bacterial; D006508:Hepatitis Antibodies; D018937:Hepatitis C Antibodies; D011935:Reagins