A comparative study of two different methods for the detection of latent tuberculosis in HIV-positive individuals in Chile

Int J Infect Dis. 2008 Nov;12(6):645-52. doi: 10.1016/j.ijid.2008.03.005. Epub 2008 Jun 4.


Objective: To compare the performance of two tests for diagnosing latent tuberculosis (TB) infection in the HIV-positive population in Chile, in order to better identify the subjects who might benefit from TB chemoprophylaxis.

Design: This was a cross-sectional study among individuals attending three HIV outpatient clinics in Santiago, tested with a 2-TU purified protein derivative, QuantiFERON((R))-TB Gold 'in-tube' (QFT-G), and a chest X-ray.

Results: A total of 116 subjects were enrolled in the study, having a mean CD4 count of 393cells/microl (range 100-977). The tuberculin skin text (TST; 5mm cutoff) and QFT-G results were positive in 10.9% and 14.8% of the individuals, respectively, with moderate agreement between both tests (kappa=0.59). A history of both known TB exposure (odds ratio (OR) 3.46, 95% confidence interval (CI) 1.02-11.22) and past TB (OR 4.31, 95% CI 1.13-15.5) were associated with a positive QFT-G result. Only past TB was significantly associated with a positive TST result (OR 6.63, 95% CI 1.62-26.3). Among the subjects with TST<5mm, 8.2% were positive by QFT-G test. These individuals had a lower mean CD4 cell count than those detected positive by both tests (328cells/microl and 560cells/microl, respectively, p=0.03).

Conclusions: In this population of HIV-infected individuals, QFT-G and TST showed an acceptable level of agreement, although QFT-G appears less affected by more advanced immunosuppression.

Publication types

  • Comparative Study
  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • AIDS-Related Opportunistic Infections / diagnosis*
  • AIDS-Related Opportunistic Infections / epidemiology
  • AIDS-Related Opportunistic Infections / microbiology
  • Adult
  • Aged
  • CD4 Lymphocyte Count
  • Chile / epidemiology
  • Female
  • HIV Infections / complications*
  • HIV Infections / immunology
  • Humans
  • Interferon-gamma / blood*
  • Male
  • Middle Aged
  • Mycobacterium tuberculosis*
  • Reagent Kits, Diagnostic
  • Reproducibility of Results
  • Tuberculin Test*
  • Tuberculosis, Pulmonary / diagnosis*
  • Tuberculosis, Pulmonary / epidemiology
  • Tuberculosis, Pulmonary / microbiology
  • Young Adult


  • Reagent Kits, Diagnostic
  • Interferon-gamma