The Role of QuantiFERON ® -TB Gold and Tuberculin Skin Test as Diagnostic Tests for Intraocular Tuberculosis in HIV-Positive and HIV-Negative Patients in South Africa.

PURPOSE: To compare QuantiFERON®-TB Gold and tuberculin skin testing as diagnostic tests for intraocular tuberculosis in HIV positive and negative patients.

METHODS: A prospective study evaluating two different tests to help diagnose intraocular tuberculosis.

RESULTS: Thirty-five of 106 patients (33.0%) were diagnosed with intraocular tuberculosis including 11 (31.4%) with HIV infection. Patients were 6.95 times more likely to have intraocular tuberculosis if TST alone was positive (p < 0.001) versus 2.19 times more likely if Quantiferon alone was positive (p = 0.04). Tuberculin skin testing showed superior specificity (60.3% vs 33.3%) (p = 0.001) but similar sensitivity (90.3% vs 85.7%), positive (54.9% vs 40.5%) and negative predictive values (92.1% vs 81.5%) compared to Quantiferon. Specificity did not increase significantly if both skin testing and Quantiferon were positive.

CONCLUSIONS: In South Africa, with its high HIV burden and limited public health resources, Quantiferon testing should not replace tuberculin skin testing as it provides little additional diagnostic information.