Aim: To study the utility of interferon-g release assays (QuantiFERON TB gold test) in a south Indian patient population of intraocular inflammation.
Design: Evaluation of a diagnostic test- a pilot study from January 2007 to October 2008.
Materials and methods: QuantiFERON TB gold test was performed on the following groups of patients following an informed consent. Group A included healthy volunteers without any exposure to tuberculosis (TB) or past history of TB (n=22). Group B included patients with active systemic TB diagnosed by the demonstration of acid-fast bacilli or by the histopathology finding of caseation with granuloma formation from the sputum, lymph node, skin or intestinal biopsies (n=26). Group C included patients with uveitis of known etiologies other than intraocular TB without any history of exposure to active TB (n=21). Group D included patients with a diagnosis of presumed intraocular TB, who responded to antitubercular therapy by decreased or no recurrences following treatment and with a minimum of nine months follow-up following initiation of antitubercular therapy (n=39).
Results: The sensitivity and specificity of the QuantiFERON TB gold test to pick up active systemic TB was 58% and 77% respectively. The sensitivity and specificity of the QuantiFERON TB gold test to pickup intraocular TB was 82% and 76% respectively.
Conclusions: QuantiFERON TB gold test alone may not be specific for intraocular TB. The significance of this test in a case scenario needs to be interpreted with clinical presentation and other evidences for intraocular TB.