Prevalence, Risk Factors, and Result Features in the Detection of Latent Tuberculosis Infection in Thai Healthcare Workers Using QuantiFERON-TB Gold Plus

Introduction Latent tuberculosis infection (LTBI) is an enormous reservoir for tuberculosis (TB), and healthcare workers (HCWs) are at high risk for TB infection. QuantiFERON-TB Gold Plus (QFT-Plus) is an alternative to the tuberculin skin test for LTBI detection, but data on its application and LTBI detected by QFT-Plus in high TB burden countries are limited. This study aimed to determine the prevalence of LTBI and its risk factors, and to investigate the QFT-Plus results in Thai HCWs. Methods A cross-sectional analytical study was conducted among HCWs at a secondary care hospital in Health Region 5, Thailand. Eligible HCWs were enrolled and underwent QFT-Plus testing. Interferon-gamma (IFN-γ) values in tubes were analysed. The prevalence and associated risk factors for LTBI were assessed based on laboratory and sociodemographic data. Logistic regression analyses were applied to calculate odds ratios (OR, aOR) reported with 95% confidence intervals (CI). Results Of the 269 participants enrolled, their median age was 42 years and 93.31% (n = 251/269) were female. The majority (n = 178/269, 66.17%) were nurses or nurse assistants and 42.75% (n = 115/269) worked in the inpatient medical wards. Overall, the QFT-Plus results showed 110 (40.89%) positive with good agreement (93.68%; κ 0.87) and high correlation (Spearman's ρ 0.91) of IFN-γ concentrations in the two antigen tubes. A true difference in IFN-γ values for predicting a recent infection was found about 7.81% (n = 21/269). By univariate and multivariate analyses, the participants' age > 40 years (OR = 3.21, 95% CI: 1.84-5.64%; aOR = 2.05, 95% CI: 1.07-3.96%), and employment duration > 10 years (OR = 3.19, 95% CI: 1.66-6.37%; aOR = 2.34, 95% CI: 1.05-5.21%) were significantly associated with the increased risk of LTBI (p value < 0.05). Conclusions The prevalence of LTBI among these HCWs was high, and the increased risk factors for LTBI according to QFT-Plus positivity were age over 40 years and working time in the hospital for more than 10 years. It is important to screen HCWs in this setting for LTBI, particularly those with long employment durations and older ages. The high prevalence of LTBI suggests that LTBI management, such as regular screening and treatment, should be considered together with strengthening preventive measures, especially in high-risk groups.