COMPARISON OF INTERFERON-GAMMA RELEASE ASSAY VERSUS TUBERCULIN SKIN TEST FOR LATENT TUBERCULOSIS SCREENING IN HEMODIALYSIS PATIENTS

Early diagnosis and proper treatment of latent tuberculosis infection (LTB1) in patients with end stage renal diseases (ESRD) is critical to reduce increased reactivation risk of LTB1. However; this condition is known to decrease responsiveness to the tubercidin skin test (TST). A new, diagnostic test [QuantiFERON-TB Gold in-tube (QFT-GIT)] has been developed using mycobacterium tuberculosis specific antigens for the identification of LTB1. We aimed to evaluate the two test methods among hemodialysis patients for their diagnostic usefulness. We performed a cross-sectional comparison study on 275 ESRD recruits tested for LTB1 using the TST and QTF-GIT. Valid TST and QFT-GIT results were available for 259 and 246 patients, respectively. Overall, 46.7% of 246 patients were tested positive for the QTF-GIT and 35.5% of 259 were found to be TST positive. The QTF-GIT but not TST results were correlated with the history of tuberculosis: conversely, QTF-GIT and TST results were not associated with contact to tuberculosis. Moreover, QTF-GIT test generated indeterminate results in 10.4% of subjects. The concurrence between the two test methods was poor (67.8%, kappa = 0.34). Inconsistent results, most of which were, tested as TST negative/QTF-GIT positive were observed in 32.2% patients. The present results suggest that the QTF-GIT is more sensitive than TST in the detection of LTB1 among renal dialysis patients. Nevertheless, large longitudinal studies are required for more accurate results.