Evaluation of QuantiFERON-TB Gold In-Tube in human immunodeficiency virus infection and in patient candidates for anti-tumour necrosis factor-alpha treatment.

SETTING

Cross-sectional study at four out-patient clinics in a single referral centre in Italy.

OBJECTIVE

To evaluate the performance of QuantiFERON-TB Gold In-Tube (QFT-GIT) in human immunodeficiency virus (HIV) infected adults and in patients with immune-mediated inflammatory diseases (IMIDs) who are candidates for anti-tumour necrosis factor-alpha (TNF-alpha) treatment.

DESIGN

A total of 402 immunocompromised patients were enrolled, including 207 HIV-infected individuals and 195 IMID patients scheduled for anti-TNF-alpha treatment. Tuberculin skin test (TST) and QFT-GIT were performed. For active tuberculosis (TB), test results were compared with microbiological, histopathological and clinical diagnoses.

RESULTS

In HIV-infected patients, the level of agreement between the tests was 68% and QFT-GIT sensitivity was 66% (95%CI 47-82). We found a large proportion of indeterminate QFT-GIT results (33.4%), which correlated with CD4 count < 200 cells/microl (P < 0.0001). The degree of agreement with TST was higher in IMID patients (81.6%). Factors associated with discordant positive TST and negative QFT-GIT results were bacille Calmette-Guérin vaccination (P = 0.0001), previous TB (P = 0.0001) and agricultural work (P = 0.0005).

CONCLUSION

The performance of QFT-GIT varies between different types of immunocompromised patients. Interferon-gamma release assays should not be used to confirm or rule out a diagnosis of active TB in HIV-infected adults. As there were no cases of active TB in the IMID subgroup, it was difficult to determine which test performs better in this population.