title: Effect of Pregnancy on Interferon Gamma Release Assay and Tuberculin Skin Test Detection of Latent TB Infection Among HIV-Infected Women in a High Burden Setting.
abstract: Peripartum immunologic changes may affect latent tuberculosis infection (LTBI) diagnostic performance among HIV-infected women.
  
  
  
  HIV-infected women were serially tested with tuberculin skin test (TST) and interferon gamma release assay [QuantiFERON TB Gold In-tube (QFT)] in pregnancy and 6 weeks postpartum in Kenya. Prevalence, sensitivity and agreement, and correlates of QFT/TST positivity were assessed. Quantitative QFT mitogen and Mycobacterium tuberculosis antigen (Mtb-Ag) responses were compared by peripartum stage. Incidence of test conversion at 6 weeks postpartum was evaluated in baseline TST-/QFT- women.
  
  
  
  Among 100 HIV-infected women, median age was 26 years, median CD4 was 555 cells per cubic millimeter, and 88% were on antiretrovirals. More women were QFT+ than TST+ in both pregnancy (35.4% vs. 13.5%, P = 0.001) and postpartum (29.6% vs. 14.8%, P < 0.001). Among 18 consistently QFT+ women, 8 (44%) converted from TST- to TST+, with improved test agreement postpartum (56.9%, κ = 0.20 to 82.4%, κ = 0.60). Three initially QFT-/TST- women had test conversion (TST+ and/or QFT+), suggesting new infection (incidence 13.4/100 person-years). Mean QFT mitogen (4.46 vs. 7.64 IU/mL, P < 0.001) and Mtb-Ag (1.03 vs. 1.54 IU/mL, P = 0.03) responses were lower among all women retested in pregnancy vs. postpartum, and specifically among persistently QFT+ women (Mtb-Ag: 3.46 vs. 4.48 IU/mL, P = 0.007). QFT indeterminate rate was higher in pregnancy (16%) compared with postpartum (0%) because of lower mitogen response.
  
  
  
  QFT identified >2-fold more women with LTBI compared with TST in pregnancy and postpartum. Lower QFT Mtb-Ag and mitogen responses in pregnancy compared with postpartum suggest that pregnancy-associated immunologic changes may influence LTBI test performance.
authors.affiliation: *Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA; †Department of Pediatrics, Emory University School of Medicine and Children's Healthcare of Atlanta, Atlanta, GA; Departments of ‡Research and Programs; §Reproductive Health, Kenyatta National Hospital, Nairobi, Kenya; Departments of ‖Global Health; ¶Biostatistics, University of Washington, Seattle, WA; #Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Washington Harborview Medical Center, Seattle, WA; **Firland Northwest TB Center, Seattle, WA; and Departments of ††Pediatrics; ‡‡Epidemiology, University of Washington, Seattle, WA.
authors.forename: Sylvia M
authors.initials: SM
authors.lastname: LaCourse
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Cranmer
authors.forename: Daniel
authors.initials: D
authors.lastname: Matemo
authors.forename: John
authors.initials: J
authors.lastname: Kinuthia
authors.forename: Barbra A
authors.initials: BA
authors.lastname: Richardson
authors.forename: David J
authors.initials: DJ
authors.lastname: Horne
authors.forename: Grace
authors.initials: G
authors.lastname: John-Stewart
mesh_terms: D000328:Adult; D003955:Diagnostic Tests, Routine / Q000379:methods; D005260:Female; D015658:HIV Infections / Q000150:complications* / Q000276:immunology*; D006801:Humans; D059425:Interferon-gamma Release Tests / Q000379:methods*; D007630:Kenya; D055985:Latent Tuberculosis / Q000175:diagnosis*; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D058725:Peripartum Period; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000276:immunology*; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D014374:Tuberculin Test / Q000379:methods*; D055815:Young Adult