Objectives: To determine the agreement of Mycobacterium tuberculosis (MTB) antigen-based skin test (TBST) with interferon-gamma release assay (IGRA) in elderly individuals aged ≥ 65 years beyond instruction for use in China.
Methods: Based on the baseline survey of randomized controlled trial with objective to explore suitable regimen for tuberculosis (TB) preventive treatment, MTB infection was tested using TBST and IGRA in parallel in rural residents aged 50-70 years by means of a cross-sectional study design.
Results: A total of 21219 participants with both TBST and IGRA results were included in this analysis. The concordance between TBST and IGRA was 89.4% (95%CI: 89.0 - 89.8%) with a kappa coefficient of 0.61 (95%CI: 0.60 - 0.62). In those aged ≥ 65 years, the concordance was 86.5% (95%CI: 85.6 - 87.4%) with a kappa coefficient of 0.55 (95%CI: 0.52 - 0.58). 21.2% (35/165) of the participants with indeterminate IGRA results were TBST positive, and 9 of them aged ≥ 65 years.
Conclusions: The consistent agreement between TBST and IGRA in individuals aged ≥ 65 years suggests that TBST has potential to be used in the elderly with age beyond instruction for use in China. The respective diagnostic performance of each test will be analyzed when the longitudinal data on incident TB be obtained in the future.
Keywords: Elderly; Interferon-gamma release assay; Latent tuberculosis infection; Mycobacterium tuberculosisantigen-based skin test; Tuberculosis.
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