The LTBI survey using 2 IGRA tests among the elderly in Eastern China

Who

• Study population: 1,583 elderly individuals aged ≥65 years

• Setting: Community-dwelling older adults attending routine health check-ups

• Subgroup for agreement analysis: 108 participants aged ≥65 years

• Sex distribution: Male-to-female ratio ≈ 0.95:1 in the main study

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What

• Primary outcomes:

  • The prevalence of latent tuberculosis infection (LTBI) among elderly adults was 26.78%.

  • Risk factors positively associated with LTBI included:

    • Male sex (Adjusted OR = 1.64; 95% CI: 1.25–2.15)

    • Former smoking (Adjusted OR = 1.42; 95% CI: 1.01–2.01)

    • Exercising at least once per week (Adjusted OR = 2.21; 95% CI: 1.03–4.75)

• Diagnostic agreement findings:

  • The domestic AIMTB Rapid Test Assay showed high agreement with QFT-Plus:

    • Overall agreement: 92.59%

    • AUC for AIMTB: 0.952

    • Optimal AIMTB cutoff: 24.02 pg/mL IFN-γ

• Authors’ conclusion: LTBI burden among the elderly is substantial and warrants targeted screening. AIMTB demonstrates strong diagnostic performance and may reduce screening costs in high-TB-burden, resource-limited settings.

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When

• Data collection period: Not specified

• Conducted during recent years following implementation of the Tuberculosis-Free Community project.

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Where

• Location: Lanxi City

• Region: Central Zhejiang Province (Jinhua area), China

• Context: Rural/suburban setting with high pulmonary TB notification rates among the elderly

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Why

• To address the high burden of TB and LTBI in older adults in aging populations.

• To identify factors associated with LTBI in the elderly.

• To evaluate agreement between a domestic LTBI assay (AIMTB) and a conventional interferon-gamma release assay (IGRA), supporting scalable screening strategies in developing countries.

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How

• Study design: Community-based cross-sectional study with an embedded diagnostic agreement analysis

• Sampling: Random selection of two subdistricts; daily recruitment of eligible elderly residents

• Sample size: Calculated minimum 1,261; final enrollment 1,583

• Data collection:

  • Structured questionnaire (demographics, BMI, smoking, alcohol use, exercise, diabetes)

  • LTBI testing using:

    • QFT-Plus

    • AIMTB Rapid Test Assay

• Statistical analysis:

• Multivariable logistic regression for risk factors

• Agreement analysis (kappa, correlation, Bland–Altman)

• ROC curve to optimize AIMTB cutoff values

Source: Jiang, X., Feng, Y., Yu, Z., Chen, B., Wang, W., Jiang, G., Hu, L., Tong, W., Chen, Q., Zhang, M. and Zhu, Y., 2025. The latent tuberculosis infection survey using two interferon γ release assay tests among the elderly in a well-confined rural county in Eastern China. BMC geriatrics, 25(1), p.1035.