Diagnostic potential of interferon-gamma release assay to detect latent tuberculosis infection in kidney transplant recipients

Background: Latent tuberculosis (TB) infection (LTBI) is screened by using clinical assessment, tuberculin skin test (TST), chest radiography, and recently by interferon-gamma release assays (IGRA). The objective of this study was to evaluate the diagnostic potential of QuantiFERON((R))-TB Gold In-Tube test (QFT) for diagnosing LTBI in patients planned for kidney transplantation. Methods: All adult patients with end-stage renal disease, evaluated for kidney transplantation in a referral center from August 2008 till May 2013, were enrolled, after consenting in a prospective, observational, non-interventional study. LTBI diagnosis was conducted by TST, chest x-ray, and clinical assessment, followed by IGRA by QFT. Results: Overall, 278 patients were enrolled and kidney transplantation was performed in 173 patients. Contributed follow-up was 836.5 patient-years, and TB-free transplant duration was 478.5 patient-years. By standard methods, LTBI was diagnosed in 14 patients. Peri-transplant chemoprophylaxis was given to 53 patients, which included recipients of organs from all deceased donors and living donors with LTBI. QFT was positive in 70 patients, negative in 200 patients, and indeterminate in 8 patients. The agreement between LTBI diagnosis using standard methods and IGRA by QFT was poor (kappa: 0.089+0.046, P-value=.017). Twenty-seven of the QFT-positive patients were transplanted and only one was given isoniazid preventive therapy. None of the transplant recipients developed TB after a median follow-up of 25months (range 2-58months, mean 27months). Conclusions: The agreement of the QFT with standard diagnosis of LTBI in kidney transplant recipients was poor.