Indirect supportive evidence for diagnosis of tuberculosis-related uveitis: from the tuberculin skin test to the new interferon gamma release assays

Abstract

Purpose: To evaluate clinical and paraclinical parameters for the indirect diagnosis of tuberculosis-related uveitis (TRU).

Methods: Prospective 2-year study in a tertiary referral centre. Patients with clinically suspected TRU were recruited. Demographical and clinical data were recorded. QuantiFERON(®) -TB Gold (QFT), tuberculosis skin test (TST) and pulmonary X-ray were performed, and other possible uveitis aetiologies were ruled out. Further investigations were also performed case by case after consultation. After final assessment, standard antituberculosis therapy was started if TRU was considered highly probable. Finally, diagnosis of TRU was established according to current criteria and set as gold standard. Strength of association for TRU was determined by odds ratio and compared by appropriate tests. Concordance and binary classification tests were also assessed.

Results: The study included 103 patients, 54 men and 49 women. Mean age 45.6 years. Sixty-eight patients were Spanish-born and 35 were foreign-born. Final diagnosis included 33 (32%) cases of TRU and 70 (67%) cases with other diagnoses. Asian origin (OR = 3.50, p = 0.046), previous tuberculosis (TB) contact (OR = 2.61, p = 0.026), TB in the past (OR = 6.18, p = 0.004) and associated retinal vasculitis (OR = 7.85, p < 0.001) were significantly related to TRU. Sensitivity (S) and specificity (Sp) of the TST and QFT did not differ significantly (S 87% versus 90% and Sp 85% versus 82%, respectively) with fair agreement (k = 0.607).

Conclusion: In a Western urban multi-ethnic population, patients from Asia, TB history or contact in the past and vasculitis are at higher risk of TRU. TST and QF are complementary providing enough S and Sp to support the diagnosis.