title: Diagnosis of latent tuberculosis infection among HIV discordant partners using interferon gamma release assays.
abstract: BACKGROUND
  There is limited data on the effect of HIV status and CD4 counts on performance of Interferon-g Release assays (IGRAs) for diagnosis of latent tuberculosis infection (LTBI).
  
  
  METHODS
  A cross sectional study was conducted to assess the prevalence of and risk factors for a positive diagnostic test for LTBI, using tuberculin skin test (TST) and IGRAs among HIV-discordant couples in Zambia.
  
  
  RESULTS
  A total of 596 subjects (298 couples) were enrolled. Median CD4 count among HIV positive persons was 388 cells/μl, (range 51-1330). HIV negative persons were more likely than their HIV positive partner, to have a positive diagnostic test for LTBI with TST (203 vs 128), QFT (171 vs 109) and TSPOT (156 vs. 109). On multivariate analysis, HIV negative status was an independent predictor for a positive QFT (OR = 2.22, 95% CI 1.42- 3.46) and TSPOT (OR = 1.79, 95% CI 1.16-2.77). Among HIV positive subjects a CD4 count ≥ 388 cells/μl was associated with a positive TST (OR = 1.76 95% CI 1.10-2.82) and QFT (OR = 1.71 95% CI 1.06-2.77) but not TSPOT (OR = 1.20 95% CI 0.74-1.94).
  
  
  CONCLUSIONS
  Persons with HIV had significantly fewer positive diagnostic tests for LTBI with TST, QFT and TSPOT. Persons with a CD4 count < 388 cells/μl were less likely to have a positive TST or QFT, but not less likely to have a positive TSPOT. TSPOT may perform better than TST or QFT in HIV positive individuals.
authors.affiliation: Department of Medicine, University of Pennsylvania, Philadelphia, PA 19019, USA. naashatalati@yahoo.com
authors.forename: Naasha J
authors.initials: NJ
authors.lastname: Talati
authors.forename: Esteban
authors.initials: E
authors.lastname: Gonzalez-Diaz
authors.forename: Charles
authors.initials: C
authors.lastname: Mutemba
authors.forename: Joyanna
authors.initials: J
authors.lastname: Wendt
authors.forename: William
authors.initials: W
authors.lastname: Kilembe
authors.forename: Lawrence
authors.initials: L
authors.lastname: Mwananyanda
authors.forename: Elwyn
authors.initials: E
authors.lastname: Chomba
authors.forename: Susan
authors.initials: S
authors.lastname: Allen
authors.forename: Carlos
authors.initials: C
authors.lastname: del Rio
authors.forename: Henry M
authors.initials: HM
authors.lastname: Blumberg
mesh_terms: D000293:Adolescent; D000328:Adult; D018791:CD4 Lymphocyte Count; D003430:Cross-Sectional Studies; D005260:Female; D015658:HIV Infections / Q000150:complications* / Q000276:immunology*; D006801:Humans; D059425:Interferon-gamma Release Tests / Q000379:methods*; D055985:Latent Tuberculosis / Q000175:diagnosis* / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D012747:Sexual Partners; D014374:Tuberculin Test / Q000379:methods; D055815:Young Adult; D015024:Zambia / Q000453:epidemiology