Lessons learned from implementation of interferon-gamma release assay to screen for latent tuberculosis infection in a large multicenter observational cohort study in Brazil

Background: Interferon-gamma release assay (IGRA) has emerged as a useful tool in identifying latent tuberculosis infection (LTBI). This assay can be performed through testing platforms, such as QuantiFERON-TB Gold Plus (QFT-Plus). This in vitro test has been incorporated by several guidelines worldwide and has recently been considered for the diagnosis of LTBI by the World Health Organization (WHO). The possibility of systematically implementing IGRAs such as QFT-Plus in centers that perform LTBI screening has been accelerated by the decreased availability of tuberculin skin testing (TST) in several countries. Nevertheless, the process to implement IGRA testing in routine clinical care has many gaps. Methods: The study utilized the expertise acquired by the laboratory teams of the Regional Prospective Observational Research in Tuberculosis (RePORT)-Brazil consortium during study protocol implementation of LTBI screening of TB close contacts. Results: RePORT-Brazil includes clinical research sites from Brazilian cities and is the largest multicenter cohort of TB close contacts to date in the country. Operational and logistical challenges faced during IGRA implementation in all four study laboratories are described, as well as the solutions that were developed and led to the successful establishment of IGRA testing in RePORT-Brazil. Conclusions: The problems identified and resolved in this study can assist laboratories implementing IGRAs, in addition to manufacturers of IGRAs providing effective technical support. This will facilitate the implementation of IGRA testing in countries with a high TB burden, such as Brazil.