Comparison of the QuantiFERON TB Gold In-tube Assay With Tuberculin Skin Test for the Diagnosis of Latent Tuberculosis Infection Among HIV-infected and Uninfected Children.

BACKGROUND: Diagnosis of latent tuberculosis infection (LTBI) is facilitated by tuberculin skin testing (TST) or interferon-gamma release assays such as the QuantiFERON TB Gold In-Tube (QTF-GIT) assays. Limited data exist on the utility of interferon-gamma release assays in HIV-infected children, which may be falsely negative due to immunosuppression.

METHODS: A cross-sectional study comparing TST to QTF-GIT for the diagnosis of suspected LTBI was performed in children in Tijuana, Mexico, and in San Diego, California. Concordance between TST (≥5 mm for HIV infected and ≥10 mm for HIV uninfected) and QTF-GIT was evaluated utilizing kappa coefficients. Multivariate logistic regression assessed factors influencing the results.

RESULTS: One hundred sixty-five children (70 HIV infected and 95 HIV uninfected) were evaluated (median age, 8.0 years). Among HIV-infected children, the median CD4 cell count was 913 cells/μL, with 92.9% of subjects on antiretroviral treatment and 80.0% with an HIV RNA load <400 copies/mL (76% <50 copies/mL). Among HIV-infected children with no history of tuberculosis, 12 HIV had either a positive QTF-GIT or TST ≥ 5 mm or both, giving a suspected LTBI prevalence of 20.3% (compared with 61.3% among HIV-uninfected children). Moderate concordance was demonstrated in HIV-infected children (both tests positive, κ = 0.42; 95% confidence interval: 8.9%-75.4%) and HIV-uninfected children (both tests positive, κ = 0.59; 95% confidence interval: 43.0%-76.5%).

CONCLUSIONS: A moderate correlation exists between TST and QTF-GIT among HIV-infected and uninfected children with preserved immune function in an area of moderate tuberculosis endemicity.