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Correlation of clinical data with reactivity in the interferon-g release assay for tuberculosis antigens in HIV-infected patients
Presented by Maximilian C. Aichelburg, Austria.
Aichelburg M.C.1, Makristathis A.2, Breitenecker F.1, Eltz S.1, Aichelburg A.C.3, Rieger A.1, Kohrgruber N.1
1Vienna Medical School, Department of Dermatology, Division of Immunology, Allergy and Infectious Diseases, Vienna, Austria, 2Vienna Medical School, Department of Clinical Microbiology, Institute of Hygiene and Medical Microbiology, Vienna, Austria, 3Pulmological Centre SMZ Baumgartner Höhe, Otto Wagner-Hospital, II. Medical Department, Vienna, Austria
Background: Austria is a low-incidence country for Tuberculosis (TB), nevertheless TB rates are higher among HIV infected persons. The QuantiFERON®-TB Gold Test (QFT) might provide improved screening accuracy for patients at risk for TB but as yet has not been sufficiently evaluated in HIV-infected individuals.
Methods: In this longitudinal study, QFT was performed in 701 HIV-infected patients. To correlate positive QFT results with clinical and socio-epidemiological data, tuberculin skin testing was done and TB related clinical, socio-epidemiologic and microbiological data were gained. The mean follow-up time was 6 months.
Results: The QFT was reactive or indeterminate in 39 (5.6%) and 33 patients (4.7%), respectively. Patients with indeterminate QFT had significantly lower CD4 cells as compared to patients with positive (p=0.001) or negative (p<0.001) tests. Mean CD4 cell counts were 297, 480 and 441, respectively. Active TB was found in 3/39 QFT positive but not in negative or indeterminate individuals. In 2 of the patients, a reactive QFT revealed occult TB. Among the 39 QFT+ patients, 23 were from high-incidence countries. Six patients had previously been diagnosed with TB. Risk factors for acquiring TB-infection, i.e., origin from or recent travel to a high-prevalence country or close contact with a patient with active TB were identified in 29/39 QFT+ patients. Systemic or pulmonary symptoms without microbiological or radiological evidence of active TB were present in 22/39 QFT+ patients. Two patients with positive QFTs died during the follow-up period, one of them due to TB. Concordance for QFT and tuberculin skin test was found in 64% of patients tested. None of the QFT+ patients without evidence of active TB at baseline developed active TB during the follow-up period.
Conclusion: The QFT appears to be highly sensitive and may reveal sub- or preclinical TB even in moderately immunocompromised HIV patients.
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