Diagnostic Utility of QuantiFERON-Gold Testing in Patients with Ocular Inflammation in a Low-Endemic Tuberculosis Region

Purpose To evaluate the diagnostic value of QuantiFERON Gold (QFT-G) testing for ocular inflammation in a low prevalence tuberculosis (TB) area. Design Diagnostic utility analysis. Methods A review was performed for all uveitis patients who underwent QFT-G testing at the University of Colorado Eye Center from 2009 to 2022. Records were reviewed to assess QFT-G positivity rate and to identify which patients were tested for diagnostic purposes, defined as meeting the Standardization of Uveitis Nomenclature (SUN) criteria for tubercular uveitis (TBU): anterior uveitis with iris nodules, serpiginous-like choroiditis, choroidal nodule resembling a tuberculoma, multifocal choroiditis, or occlusive retinal vasculitis. Results A total of 388 patients with uveitis underwent QFT-G testing, of which 17 (4.38%) were positive. Only one (5.88%) patient had true TBU with anterior uveitis with iris nodules. The remaining 16 (94.1%) patients did not meet SUN criteria for TBU and were incidentally found to be QFT-G positive during laboratory work-up prior to immunosuppression. The positive predictive value was 100% when QFT-G testing was performed in patients who met SUN criteria for TBU, whereas the positive predictive value was 0% for QFT-G testing performed in patients who did not meet SUN criteria for TBU. Conclusion In low prevalence areas, the majority of QFT-G positive tests in uveitis patients are coincidental and unrelated to their uveitic disease process. The diagnostic value of a TB test is likely to be minimal unless the SUN clinical criteria for tubercular uveitis are met.