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 (5mm for HIV infected and 10mm 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/L, 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 5mm 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, = 0.42; 95% confidence interval: 8.9%-75.4%) and HIV-uninfected children (both tests positive, = 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.