Poor agreement between QuantiFERON-TB Gold test and tuberculin skin test results for the diagnosis of latent tuberculosis infection in rheumatoid arthritis patients and healthy controls

BACKGROUND/AIMS: We investigated the agreement between the QuantiFERON-TB Gold (QFT-Gold) test and the tuberculin skin test (TST) in the diagnosis of latent tuberculosis infection in patients with rheumatoid arthritis (RA), compared with healthy controls, in Korea. METHODS: We recruited 64 patients with RA and 79 healthy controls at two university hospitals in South Korea. The participants underwent both the QFT-Gold test and the TST simultaneously between August 2006 and February 2009. All patients were diagnosed using the classification criteria for RA revised in 1987 by the American College of Rheumatology. Bacillus Calmette-Guerin vaccination status and current medications were evaluated, and disease activities were assessed using the Disease Activity Score in 28 joints. Eleven patients with RA produced indeterminate QFT-Gold test results and were thus excluded from the kappa analysis. RESULTS: Based on an induration of 10 mm in diameter as the TST cutoff value, the QFT-Gold test and TST demonstrated 75.0% agreement (kappa = 0.23) in patients with RA and 75.9% agreement (kappa = 0.19) in healthy controls. Among the 56 patients with RA who had negative TST results, 11 patients (17.2%) also yielded indeterminate QFT-Gold results. CONCLUSIONS: Our study showed poor agreement between the results of the QFT-Gold test and the TST in both RA patients and healthy controls. Based on these findings, we emphasize the importance of making clinical decisions in the diagnosis of latent tuberculosis in Koreans with or without RA.

Role of the quantiferon-TB gold in tube in ruling out tuberculosis in end stage renal disease patients receiving hemodialysis

It is difficult to diagnose tuberculosis [TB] in dialysis patients because of the high rate of extrapulmonary TB in these patients compared with the general population. Recently, a new diagnostic test called QuantiFERON[QFT] has been developed and shown promise as a diagnostic tool for active TB diseases and latent TB infection. The aim of the present study was to analyze the performance of QuantiFERON-TB Gold in tube [QFT-G] in end stage renal disease patients receiving hemodialysis. QuantiFERON Gold in tube [QFT-GIT] were prospectively performed in 50 end stage renal disease [ESRD] cases undergoing hemodialysis [HD], including 6 patients with active TB and evaluated the utility of this test in dialysis patients. Among 50 dialysis patients, positive QFT results occurred in 10 [20%], negative QFT results occurred in 25 [50%] and indeterminate QFT results occurred in 15 [30%]. All six active TB patients had positive QFT results, and none of the 25 patients with negative results had active TB. Among 7 patients with a history of active TB, 2 [28.5%] had positive results. Although the indeterminate rate was relatively high, no patient with an indeterminate result had active TB. Among 30 cases after excluding the patients with previous TB and indeterminate results, the sensitivity of the QFT is 100% [6 of 6] and the specificity is 91.6% [22 of 24 cases]. Our data suggest that the QFT test is a useful supplementary tool for the diagnosis of active TB even in dialysis patients. Negative and indeterminate results on this test may be used to exclude the presence of active TB