| Summary: | Introduction: Malignancies are among the most important risk factors for progression of latent tuberculosis (TB) to active disease. The tuberculin skin test (TST) has been used worldwide for the diagnosis of latent TB. New T-cell-based interferon-gamma release assays such as QuantiFERON-TB Gold In-Tube (QFT-GIT) have yielded promising results in this regard, but little information is available on their use in hematopoietic stem cell recipients. The aim of this study was to evaluate the agreement between QFT-GIT and TST in the diagnosis of latent TB in hematopoietic stem cell transplantation (HSCT) candidates.
Materials and Methods: Patients who underwent HSCT in our hospital between November 1, 2013 and July 31, 2015 were retrospectively evaluated from patient files. Those who had both QFT-GIT and TST before transplantation were included in the study. Isoniazid prophylaxis was initiated one week before transplantation and continued for nine months for patients with positive results in one or both tests. The kappa (κ) coefficients were calculated to analyze the agreement between two tests.
Results: The study included 122 patients, (53.3% autologous and 46.7% allogeneic hematopoietic stem cell recipients). The median age was 43.5 years (25-75% IQR: 30-54) and 73% were men. Bacillus Calmette-Guérin (BCG) scars were seen in 84.4% of the patients. Tuberculin skin test and QFT-GIT test were positive in 38 (31.1%) and 26 (21.3%) of the patients, respectively. Both TST and QFT-GIT were positive in 17 patients (13.9%). There was no statistically significant relationship between the two tests and BCG scars. Statistically significant, fair agreement was found between positive TST and QFT-GIT results (κ=0.37 and p<0.001). Patients were followed until July 2018. The median follow-up time of all patients was 39 months (IQR: 10.8-49.0). None of the patients developed active TB during follow-up, but 44.3% of the patients died due to malignancy and/or opportunistic infections.
Conclusion: Further research is needed to demonstrate the agreement between these two tests in the diagnosis of latent TB in HSCT patients. For now, the combination of these two tests seems to be most rational for these patients.
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