Prevalence of Latent Tuberculosis Infection in Persons with and Without Human Immunodeficiency Virus Infection Using Two Interferon-gamma Release Assays and Tuberculin Skin Test in a Low Human Immunodeficiency Virus Prevalence, Intermediate...

Background: The risk of tuberculosis (TB) is higher in human immunodeficiency virus (HIV)-infected patients and intravenous drug users (IDUs). We determined the prevalence and risk factors of latent TB infection (LTBI) in individuals with or without HIV infection, including IDUs, in a country with a low HIV prevalence, an intermediate TB burden, and a high Bacillus Calmette-Guérin (BCG) vaccine coverage using two interferon-gamma release assays (IGRAs) and the tuberculin skin test (TST).

Methods: For this prospective, cross-sectional study, HIV-infected and -uninfected patients from a regional hospital and medical center in Taiwan were enrolled. Results of the two IGRAs [QuantiFERON-TB Gold (QFT-G) and QuantiFERON-TB Gold In-Tube (QFT-GIT)] and the TST were compared. Risk factors for positivity were analyzed.

Results: We recruited 233 patients [198 (85%) men; mean age, 39.4 years]. Most patients (74%) were BCG vaccinated. The prevalence of LTBI was estimated to be 22.8% by TST, 15.9% by QFT-G, and 20.6% by QFT-GIT. HIV-infected individuals had fewer positive QFT-GIT [7.0% vs. 28.6%, p < 0.001, adjusted odds ratio (aOR) = 0.28, p = 0.05] and TST results, and more indeterminate QFT-G responses (9.3% vs. 0.7%, p = 0.002). Concordance between IGRAs and TST was very poor in HIV-infected patients (κ < 0.05). Independent risk factors for IGRA positivity were increasing age (QFT-G: aOR = 1.98, p = 0.03; QFT-GIT: aOR = 2.00, p = 0.01) and IDUs (aOR = 4.33, p = 0.05 by QFT-G).

Conclusion: HIV-infected persons had a significantly lower response to both IGRAs and TST. High discordance was found between the two generations of IGRAs and between IGRAs and TST. Increasing age, a known risk factor for LTBI, was significantly associated with IGRAs, but not with TST.