The value of an immune response to Mycobacterium tuberculosis in patients with chronic posterior uveitis revisited: utility of the new IGRAs.

PURPOSE: To explore the utility of a specific immune response to Mycobacterium tuberculosis in a population of immunosuppressed idiopathic chronic posterior uveitis patients, by means of a tuberculosis-specific interferon-gamma release assay.
DESIGN: Prospective, interventional case series.
METHODS: A total of 31 referred patients with severe idiopathic chronic uveitis or panuveitis and 52 controls were screened for a specific immune response to tuberculosis. After ruling-out specific uveitis entities, presumed tuberculosis-related uveitis was initially considered when ophthalmologic findings were consistent with tubercular uveitis, and a specific immune response to M. tuberculosis confirmed by QuantiFERON, despite inability to detect M. tuberculosis. Clinical responses to antitubercular treatment were recorded.
RESULTS: The prevalence of an immune response to M. tuberculosis was 15.38% in controls and 32.25% in uveitis patients (OR=2.619, P=0.07). Two patients were QuantiFERON indeterminate (6.4%). After excluding seven specific uveitis entities (OR=3.66, P=0.03), eight QuantiFERON-positive and one QuanTIFERON-negative uveitis patients were initially treated for presumed tuberculosis-related uveitis. All but one had no evidence of active systemic involvement. None had been previously diagnosed with tuberculosis, but unsuccessfully treated with immunosuppressors. After a 9-month tuberculostatic treatment, seven QuantiFERON -positive and one QuantiFERON-negative patients exhibited decreased intraocular inflammation, visual acuity improvement, and no relapses. Estimated QuantiFERON sensitivity and specificity were 82 and 100%, respectively, with a PPV=100% and an NPV=86%.
CONCLUSIONS: QuantiFERON was useful for antituberculous treatment decision-making in chronic posterior uveitis immunosuppressed patients from areas with an intermediate-high prevalence of tuberculosis.