title: The impact of combined antiretroviral therapy on biologic false-positive rapid plasma reagin serologies in a longitudinal cohort of HIV-infected persons.
abstract: BACKGROUND
  Our objective was to determine the impact of combination antiretroviral therapy (cART) and the degree of immunosuppression on biologic false-positive (BFP) rapid plasma reagin (RPR) tests among persons infected with human immunodeficiency virus (HIV).
  
  
  METHODS
  This was a nested retrospective study of HIV-infected patients enrolled in the Johns Hopkins HIV Clinical Cohort. BFP RPR was defined as a reactive RPR and a nonreactive fluorescent treponemal antibody-absorption (FTA-ABS) test. Patients with BFP tests were compared to 2 control groups: HIV-infected patients (1) with active syphilis (reactive RPR and FTA-ABS) and (2) without current syphilis (nonreactive RPR). A persistent BFP test was defined by having at least 2 visits with consistent BFP at all visits.
  
  
  RESULTS
  Of 711 patients with HIV, 96 (13.5%) had BFP tests and 342 (48.1%) had syphilis. Twenty-two of 96 (23%) had persistent BFP tests. cART use was associated with decreased odds of BFP tests compared to having syphilis (adjusted odds ratio [AOR], 0.31; 95% CI, .15-.63) and those with nonreactive RPR (AOR, 0.42; 95% CI, .22-.81). cART use was also associated with decreased odds of BFP persistence (AOR, 0.07; 95% CI, .01-.33). Neither CD4 count nor HIV RNA was significantly associated with BFP test results. Lower RPR titers, younger age, and injection drug use were associated with increased odds of BFP.
  
  
  CONCLUSIONS
  The use of cART appears to decrease the odds of BFP RPR tests. This finding suggests that nontreponemal titer fluctuations in persons with HIV may reflect the influence of factors unrelated to syphilis disease activity.
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Ikwo K
authors.initials: IK
authors.lastname: Oboho
authors.forename: Kelly A
authors.initials: KA
authors.lastname: Gebo
authors.forename: Richard D
authors.initials: RD
authors.lastname: Moore
authors.forename: Khalil G
authors.initials: KG
authors.lastname: Ghanem
mesh_terms: D000328:Adult; D044966:Anti-Retroviral Agents / Q000627:therapeutic use*; D015331:Cohort Studies; D004359:Drug Therapy, Combination; D005189:False Positive Reactions; D005260:Female; D015658:HIV Infections / Q000097:blood / Q000188:drug therapy* / Q000382:microbiology*; D006801:Humans; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011935:Reagins / Q000097:blood*; D012189:Retrospective Studies; D013587:Syphilis / Q000097:blood / Q000175:diagnosis* / Q000821:virology; D013588:Syphilis Serodiagnosis / Q000379:methods*
chemical_list: D044966:Anti-Retroviral Agents; D011935:Reagins
keywords: HIV; antiretroviral therapy; false-positive RPR