Perspectives of Quantiferon TB Gold test among Indian practitioners: a survey

Among the 37 responders, there were 19 uveitis specialists, 9 rheumatologists, and 9 pulmonologists with the majority having more than 7 years of experience in treating tuberculosis. Latent TB was the most common type of tuberculosis reported by 81% of the responders. Although 92% agree that Quantiferon TB Gold assay is used for the diagnosis of latent TB, only 32% use this test always in their practice. Limiting factors include the higher cost (35.14%), limited data from countries endemic for TB and hence limited interpretation of results (32.43%), the inability to differentiate active and latent TB (32.43%), and technical issues related to the test (18.92%). A combination of the Mantoux test and Quantiferon TB Gold test was the preferred test for investigation in 51% of the responders rather than solo tests.Within this group of specialists dealing with different forms of tuberculosis, perspectives of this test and preferences are many. The increased cost and limited data from India with respect to interpretation of the results are the most common limiting factors in using this test.Interferon gamma release assays (IGRAs) are new immune-based in vitro tests for detecting Mycobacterium tuberculosis (MTb) infection [1,2]. They are based on the detection of interferon gamma (IFN-γ) released by sensitized T cells on stimulation with very specific antigens, early secretory antigen target-6 and culture filtrate protein-10, both derived from a very specific region of MTb, the region of difference 1 (RD1). This segment (RD1) is deleted from all strains of BCG and the majority of environmental mycobacteria (except Mycobacterium kansasii[3], Mycobacterium szulgai, Mycobacterium marinum, Mycobacterium flavescens, and Mycobacterium gastrii). The two IGRAs that are available commercially include the T-Spot TB test (based on the ELISpot technology to directly count the number of IFN-γ-secreting T cells) and Quantiferon TB Gold In-Tube test (based on the ELISA technology, which m