QuantiFERON®-TB gold in-tube is not Useful for Diagnosing Active Tuberculosis in HIV/AIDS Patients with Severe Immunodeficiency: Results from Brazil

Abstract

Purpose: To assess interferon gamma release assay (IGRA) and tuberculin skin test (TST) performances in the diagnosis of active tuberculosis (TB) in adults with HIV/AIDS with different degrees of immunodeficiency. Methods: Cross-sectional study conducted with 90 HIV/TB-coinfected adults, Sao Paulo, Brazil. TB diagnosis was established based on the presence of positive sputum smear, culture, or anatomic-pathological examination. The participants responded to a questionnaire and were submitted to physical examination, chest x-ray (CRX), serum CD4+ and CD8+ T cell count, TST, and IGRA (QuantiFERON®-TB Gold In Tube, Cellestis, Carnegie, Australia). Results: Characteristics of 90 HIV/TB-coinfected individuals: male (60.0%), white (54.4%), single (57.3%), and average age 39 (±10.8) years with pulmonary TB (45.6%) and average CD4+ T-cell count (198.92 cells/mm3). TST was positive in 25.56%, and IGRA was positive in 65.56%. IGRA performance was better when compared to TST (p<0.001) and was able to diagnose TB with 93.75% probability when CD4+ ≥ 187 cells/mm3 ; TST showed similar efficacy when CD4+ ≥ 500 cells/mm3 . Conclusion: IGRA exhibited better performance for TB disease diagnosis in HIV-infected individuals with severe immunodeficiency when compared to TST. Nevertheless, both tests may exhibit false-negative results in this type of population. Despite the fact that IGRA has better performance than TST in the diagnosis of active TB in patients with HIV/AIDS, the practical utilization of the method seems to be limited and should be considered only for patients with CD4+ ≥ 187 cells/mm3.