To test the efficacies of a strategy for preventing tuberculosis (TB) in Indian patients with inflammatory rheumatic diseases (IRD) treated with tumor necrosis factor-alpha (TNF-alpha) inhibitor.
The screening strategy included tuberculosis skin test (TST), QuantiFERON-TB Gold (QTG) test, standard chest radiograph, and contrast enhanced-computerized tomography of the chest (CT).
Among 53 patients screened, 17 (32%) had >or= 1 test positive, with 5 (9.4%) patients having TB infection (clinical, CT, biopsy). The remaining 12 patients showed latent TB; 1 additional patient with negative screening tests was diagnosed with latent TB retrospectively for he developed TB disease within a few weeks of receiving infliximab. The remaining 35 patients tested negative with all tests. The combination of 4 screening tests gave a sensitivity of 0.83, specificity of 0.74, positive predictive value (PPV) 0.29, and negative predictive value (NPV) 0.97. Only 22 patients could afford treatment with TNF-alpha inhibitors; 19 of them were negative in the screening tests. Three patients who were positive on TST and/or QTG received prophylactic treatment with TNF-alpha inhibitor. Since implementation of the screening strategy, only 1 of 22 (4.5%) patients given TNF-alpha inhibitor developed probable TB disease.
With the use of these 4 TB screening tests in India, where TB is highly prevalent, TB could be excluded with a high degree of certainty (NPV 0.97). However, as even this combination of tests has only moderate sensitivity and specificity and poor PPV for detecting TB, vigilance may be advisable even if only one of the tests is positive.