Cellestis Pty Ltd.

Hypothesis: a combined strategy of tuberculin skin test (TST) followed by QuantiFERON-TB Gold In-Tube (QFT-IT) to confirm positivity (tuberculosis infection,in contact-tracing study will allow avoiding unnecessary preventive treatment without increasing rates of tuberculosis cases among contacts screened.
Aim of the study: to compare a combined strategy of the TST and the QFT-IT with TST alone for the diagnosis of tuberculosis infection and for therapeutic decision in contact tracing study.
Design and setting: Prospective, multicentre, comparative study in 12 hospitals in Spain.
Study population: 870 subjects, household contacts of patients with culture positive pulmonary and/or laryngeal tuberculosis will be randomized to one of two strategies: Arm A (standard practice), in which treatment decisions will be based on the TST result, and Arm B (experimental), in which treatment decisions will be based on the QFT result.
Interventions: participants in arm A will undergo TST; participants in arm B will undergo TST, and, in case of a positive result, QFT-IT as well. Participants with positive TST (arm A) and positive QFT-IT (arm B) will be diagnosed with tuberculosis infection and will be treated with isoniazid for 6 months. All participants will be followed for two years.
End-points of evaluation: development of tuberculosis and proportion of subjects for whom treatment is prescribed in each arm.

Tuberculosis (TB) is an important cause of morbidity and mortality in organ transplant recipients. Management of tuberculosis in this setting is challenging due to the complexity of diagnosis and the potential toxicity of anti-TB therapy, especially in liver transplant candidates and recipients. Although the tuberculin skin test (TST) is recommended for screening of latent tuberculosis infection (LTBI) in all candidates for liver transplantation, the performance of the TST in this setting is less than optimal, due to a lack of specificity (false-positive results due to interaction with BCG vaccine and other mycobacterial infections), and a lack of sensitivity in a population that is relatively immunocompromised. Recently, a new test named QuantiFERON-TB Gold (QFT-G) has been approved for the diagnosis of LTBI. QFT-G detects the release of interferon-gamma (IFN-γ) by sensitized white cells after incubation of whole blood with TB antigens. QFT-G is expected to be more specific than TST. However, there are no studies defining the performance of QFT-G in a population of patients on a waiting list for liver transplantation. We plan to estimate the usefulness of the QFT-G test for the diagnosis of LTBI in a cohort of patients with end-stage liver disease. We hypothesize that the QFT-G test will correlate better with the risk of LTBI. This study advances research on the prevention of a serious bacterial infection that can have devastating consequences in the post-transplant setting. The new diagnostic strategy may more accurately determine the presence of LTBI, thereby allowing appropriate therapy.