The Usefulness of Interferon-gamma Release Assay for Diagnosis of Tuberculosis-related Uveitis in Korea

PURPOSE To evaluate the usefulness of the interferon-gamma release assay (IGRA) for diagnosing tuberculosis (TB)-related uveitis (TRU). METHODS Records from 181 patients with ocular signs and symptoms suggestive of TRU and intraocular inflammation of unknown etiology were reviewed. All subjects underwent clinical and laboratory testing, including IGRA, to rule out presence of underlying disease. A diagnosis of presumed TRU was made based on an internist's TB diagnosis and a patient's response to anti-TB therapy. Sensitivity, specificity, and positive predictive values of IGRA for TRU diagnosis were calculated. Clinical characteristics were compared between patients with positive and negative IGRA results. RESULTS The sensitivity and specificity of IGRA for TRU were 100% and 72.0%, respectively. Mean age, percentage of patients with retinal vasculitis, and the anatomic type of uveitis were significantly different between patients with positive and negative IGRA results (all p ≤ 0.001). Positive IGRA rates and false-positive rates were significantly different between age and anatomic type groups (both p = 0.001). The positive predictive value of the IGRA among patients with intraocular inflammation was high (70%) when all of younger age (≤ 40 years), posterior uveitis, and retinal vasculitis were present. CONCLUSIONS The IGRA is useful for diagnosing TRU in the Korean population, especially when it is used as a screening test. Clinical characteristics, including younger age (≤ 40 years), posterior uveitis, and retinal vasculitis in IGRA-positive patients, increase the likelihood of the patient having TRU.