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P169 Latent tuberculosis infection screening of adult close contacts in london: a cost-utility analysis
  1. M Hayama1,
  2. N Green1,
  3. SL Seneviratne2,
  4. M O’Donoghue3,
  5. N Drey4,
  6. OM Kon3
  1. 1NIHR Health Protection Research Unit in Modelling Methodology and MRC Centre for Outbreak Analysis and Modelling, Imperial College London School of Public Health, London, UK
  2. 2Clinical Immunology, Royal Free Hospital, London, UK
  3. 3Chest and Allergy Department, St. Mary’s Hospital, Imperial College NHS Trust, London, UK
  4. 4School of Health Sciences, City, University of London, London, UK


Background The National Institute for Health and Care Excellence (NICE) guidelines in 2016 recommend tuberculin skin test (TST) at a 5 mm induration size cut-off for latent tuberculosis infection (LTBI) screening of adult close contacts of active tuberculosis (TB) cases. An alternative would be to use an interferon-gamma release assay (IGRA) which has a higher specificity, such as the QuantiFERON-TB Gold in Tube (QFT-GIT) or T-SPOT.TB (T-SPOT). We aimed to evaluate the cost-effectiveness of the screening and treatment of LTBI in adult close contacts with various combinations of these tests in a representative London cohort.

Methods Clinical data of adult close contacts of pulmonary TB cases who were recommended to receive TST and IGRA in a TB clinic in London between 2008 and 2010 were retrospectively reviewed. A Markov decision analytic model, using an NHS perspective and lifetime horizon, was used to compare costs and quality-adjusted life-years (QALYs) associated with 7 screening strategies followed by chemoprophylaxis: TST alone, IGRA (QFT-GIT or T-SPOT) alone, TST positive followed by IGRA, and TST negative followed by IGRA. Future costs and QALYs were discounted at 3.5% per year.

Results 381 asymptomatic close contacts aged 18 to 65 years were included in this study. The mean age was 35.2 years and the majority (75.3%) were BCG vaccinated. In the base-case analysis, QFT-GIT was the most cost-effective strategy with £6876 per QALY gained, compared to TST positive followed by QFT-GIT strategy. QFT-GIT alone averted 1.6 TB cases per 1000 contacts compared to TST positive followed by QFT-GIT.

Conclusion Of the considered testing strategies, the QFT-GIT alone is preferable for LTBI screening in adult close contacts of pulmonary TB cases in London.

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