Latent tuberculosis in rheumatoid arthritis: evaluating cellular response and high-resolution computed tomography

The diagnosis of latent tuberculosis (LTB) in patients with rheumatoid arthritis (RA) has become important with the introduction of anti-tumor necrosis factor (anti-TNF-α) agents and the appearance of active tuberculosis cases in these patients. The tuberculin skin test (TST) has limited value in patients with RA. Tests based on the release of interferon-gamma (IFN-γ) are being studied, but their role has not been well established for this group of patients. To compare the diagnosis of LTB in patients with RA by using cellular immune response to the TST and T.SPOT-TB. Additionally, findings of tomography studies compatible with LTB were used. Clinical evaluation, TST, T.SPOT-TB and high-resolution computed tomography (HRCT) in a group of patients with RA at the University Hospital of the Federal University of Goiás. Response to the TST was lower in patients with RA (13.5%) compared to the predicted values of the general population. T.SPOT-TB identified a higher number of patients with LTB than the TST (36.8%). HRCT showed changes compatible with LTB in 52.9% of the patients, including 8 of the 11 patients with negative TST and T.SPOT-TB. The TST by itself is insufficient to diagnose LTB. A higher number of positive results were obtained with T.SPOT-TB when compared to the TST. Nevertheless, it was negative in a large percentage of patients with tomography findings consistent with LTB. HRCT is readily available in most large health-care centers and it could be incorporated into the diagnostic strategy for LTB in patients with RA.