A prospective longitudinal study evaluating the usefulness of the interferon-gamma releasing assay for predicting active tuberculosis in allogeneic hematopoietic stem cell transplant recipients.

Objective: There is little information on the efficacy of interferon-gamma-releasing assays for predicting subsequent active tuberculosis in hematopoietic stem cell transplant (HCT) recipients.

Methods: We prospectively enrolled adult patients admitted for allogeneic HCT during a 3-year period in an intermediate-tuberculosis-burden country. All the patients underwent QuantiFERON-TB In-Tube (QFT-TB) assay, while those enrolled during the first 2-year period also received the tuberculin skin test (TST). We observed the development of tuberculosis after HCT for additional 6-month.

Results: Of the 391 patients, 8 developed tuberculosis. Three of the 45 patients with positive QFT-TB results developed tuberculosis, while 5 of the 346 patients with negative or indeterminate QFT-TB outcomes developed tuberculosis (rate difference 2.7 per 100 person-years, P = 0.05). Of the 169 patients who underwent both TST and QFT-TB, 5 developed tuberculosis after HCT. None of the 19 patients with positive TST developed tuberculosis. Among the 150 patients with negative TST, there were 20 with positive QFT-TB and, of these, 3 developed tuberculosis, while 2 of the 130 patients with negative or indeterminate QFT-TB assays developed tuberculosis (rate difference 6.5 per 100 person-years, P = 0.004).

Conclusion: Positive QFT-TB assay results predict subsequent development of tuberculosis in HCT recipients in whom latent tuberculosis cannot be detected by TST (NCT01021124).