0; 95% CI, 2.4–179.9). No patients were diagnosed with TB disease. In this study of 100 BCG-vaccinated adults with positive TST results, 30% also had a positive QFT-G result. The strongest

predictors of a positive QFT-G result were TST induration ≥ 16 mm, being from a high-incidence country, and having evidence of a previous, healed TB infection on a chest radiograph. These findings verify the results reported by a Canadian TB clinic, which used a similar approach that resulted in a significant reduction of the number of patients who were treated for LTBI [10]. In the Canadian study, researchers also observed that a positive QFT-G result was associated with the factors found in our study, in addition to increasing age. Additionally, our study showed that persons with a positive TST and a positive QFT

result were more likely to see more have pulmonary abnormalities suggestive of previous TB disease. This is an important finding because these persons are at high risk for developing TB disease and are priority candidates for treatment for LTBI once TB disease is excluded. In BCG-vaccinated persons with a positive TST result observed at a TB clinic in Cleveland, OH, USA, male sex and a shorter time since arrival in the United States were also significantly associated with a positive IGRA result [11]. The advent of IGRAs and their increasing availability selleck kinase inhibitor is having an important impact on setting priorities for the treatment of LTBI in an era of limited and decreasing resources [12]. Approaches to reducing the number of lower-risk persons who are started on treatment include using QFT-G as the test of choice for persons

who have had BCG vaccination or using an IGRA to verify LTBI in those who have a positive TST result. Although the sensitivity of IGRA is similar to that of the TST in patients with culture-confirmed TB, proponents of doing two tests (a TST followed by an IGRA for those who have a positive TST result) highlight the specificity of IGRAs, which approaches ≥94% in BCG-vaccinated persons [5]. In contrast, the specificity of the Methocarbamol TST is relatively low and is heterogeneous in BCG-vaccinated persons, ranging between 35% and 79%. These test parameters suggest that, in BCG-vaccinated persons, an IGRA should be the preferred test [13]. There is evidence suggesting that persons with a positive TST result and a negative QFT-G result are at low risk for developing TB disease. In a German study of 954 close contacts of culture-confirmed pulmonary TB patients, treatment for LTBI was offered only to those who had a positive QFT-G result [14]. None of the treated patients developed TB disease. In contrast, among untreated contacts, only 3.1% of TST-positive [>5 mm] and QFT-G-negative contacts developed disease, while 12.9% of contacts with a positive QFT-G result developed TB disease.