High level of discordant IGRA results in HIV-infected adults and children
SETTING: Tygerberg district, Western Cape Province, South Africa. OBJECTIVE: To measure the agreement of two interferon-gamma release assays (IGRAs) and the tuberculin skin test (TST) for the detection of Mycobacterium tuberculosis infection in human immunodeficiency virus (HIV) infected adults and children in a setting highly endemic for tuberculosis (TB). DESIGN: Cross-sectional study. RESULTS: In HIV-infected adults (n = 20) and children (n = 23), tests yielded discordant results, with 61% of individuals testing positive with T-SPOT.TB, 41% with TST and 28% with QuantiFERON® TB Gold (QTF). In children, there was poor agreement between the TST and T-SPOT.TB (kappa [κ] = -0.02), but moderate agreement between the TST and QTF (κ = 0.44). In adults, there was moderate agreement between the TST and T-SPOT.TB (κ = 0.43), and the TST and QTF (κ = 0.46). In children and adults, there was fair agreement between the T-SPOT.TB and QTF (κ = 0.33). Twenty per cent of adults had ≥1 indeterminate IGRA results. CONCLUSIONS: There is poor to moderate agreement between the TST and IGRAs in HIV-infected adults and children. T-SPOT.TB may have improved sensitivity for detection of M. tuberculosis infection in HIV-infected individuals compared to the QTF and the TST. In HIV-infected individuals, IGRA test properties are affected by test cut-off point and nil control responses. © 2008 The Union.