Validity of interferon-γ-release assays for the diagnosis of latent tuberculosis in haemodialysis patients

Abstract

Haemodialysis patients are at higher risk of developing active tuberculosis (TB) infection. However, tuberculin skin tests (TST) have limitations and the diagnostic usefulness of interferon-γ-release assays (IG-RAs) remains unclear in immunocompromised hosts including haemodialysis patients. Haemodialysis patients were enrolled from a dialysis centre in Korea, an intermediate TB-burden country with a high bacille Calmette–Guérin (BCG) vaccination rate. The QuantiFERON-Gold TB In tube test® (QFT) and the T-SPOT TB test® (T-SPOT) were performed, along with the TST. We stratified patients to low- and high-risk groups, according to the risk factors for latent TB. Association between each of the three diagnostic tests and the risk of latent TB was analysed. One hundred and sixty-seven patients were enrolled. The positive rates for the TST, the QFT and T-SPOT were 23.5, 45.9 and 60.4%, respectively. Previous BCG vaccination increased the TST-positive rate in the low-risk group (OR 4.438), whereas it affected neither QFT nor T-SPOT. The positive QFT rates were 41.2 and 62.5% in the low- and high-risk groups, respectively. The QFT was associated with the high-risk group (OR 2.578), whereas the TST was not. The positive T-SPOT rates were 58.9 and 65.7% in the low- and high-risk groups, respectively. The frequency of indeterminate results was higher for the QFT (12.6%) compared with the T-SPOT (4.8%). In conclusion, the IG-RAs can be useful for the diagnosis of latent TB infection in haemodialysis patients.