Utility of QuantiFERON-TB Gold in-tube testing for latent TB infection in HIV-infected individuals

Abstract

Setting: Urban inner city human immunodeficiency virus (HIV) clinic.

Objective: To evaluate tuberculin skin testing (TST) and QuantiFERON-TB Gold (QFT-G) testing in an HIV-infected population relative to the presence of risk factors for latent tuberculosis infection (LTBI).

Design: Cross-sectional analysis of the response of a whole blood gamma interferon release assay to early secreted antigenic target 6 (ESAT-6) and culture filtrate protein 10 (CFP-10) antigens and TST relative to known risk factors for LTBI.

Results: Of 207 subjects enrolled, four were excluded due to missing data and three specimens yielded discordant results. Ten specimens were indeterminate due to inadequate response to mitogen. All indeterminate results occurred in subjects with CD(4) counts <200 cells/mm(3). Eleven QFT-G results and 13 TST results were positive. The concordance between TST and QFT-G was poor (kappa 0.38). QFT-G results were more likely than TST to be associated with risk factors for LTBI.

Conclusions: QFT-G, but not TST, showed a statistically significant association between the number of risk factors for LTBI and a positive result (OR 1.6). QFT-G testing may be more useful than TST in individuals with HIV infection.