The value of QuantiFERON®TB-Gold in the diagnosis of tuberculosis among dialysis patients

Abstract

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. We examined 162 dialysis patients admitted to a single institute, including 8 patients with active TB, and evaluated the utility of this test in dialysis patients. Among 162 dialysis patients, positive QFT results occurred in 28 (17.3%), negative QFT results occurred in 95 (58.6%) and indeterminate QFT results occurred in 39 (24.1%). All eight active TB patients had positive QFT results, and none of the 95 patients with negative results had active TB. Among 23 patients with a history of active TB, 10 (43.5%) had positive results. Although the indeterminate rate was relatively high, no patient with an indeterminate result had active TB. Factors such as shorter duration of dialysis, lower lymphocyte count and higher white blood cell count were associated with indeterminate results. Among 105 cases after excluding the patients with previous TB or indeterminate results, the sensitivity of the QFT is 100% (8 of 8) and the specificity is 89.7% (87 of 97 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.