Characteristics of a large latent tuberculous infection screening programme using QuantiFERON^®-TB Gold in Korea

Background As mentioned in the 'Action Strategy for TB Safe Korea' in March 2017, almost 2 million Koreans were screened for latent tuberculous infection (LTBI) in 2017. As a preliminary step, the Korean Institute of Tuberculosis (KIT) screened 23 824 individuals from various population groups. The present study aimed to characterise the data collected from the screening programme using the QuantiFERON®-TB Gold In-Tube (QFT) assay. Methods Interferon-gamma release assays were performed using the manual QFT or automated DS2 instruments. Statistical analyses were performed using Stata software. Turnaround time (TAT) was defined as the average time required from submission of whole blood samples by each regional laboratory to the reporting of results by the central laboratory. Results Seventeen individuals (0.1%) had indeterminate results on repeat testing, 4519 (18.98%) screened positive and 19 288 (81.0%) were screen-negative. The group of social welfare workers had the highest positivity rate, at 27.2%. Of the 11 regions in Korea, the Gyeonggi Region had the highest positivity rate, at 25.8%. The overall mean ± standard deviation for TAT was 3.05 ± 1.66. Conclusion These findings provide information on LTBI prevalence in a Korean population, and will be helpful in implementing the LTBI screening strategy for those participating in the Action Strategy for TB Safe Korea.