, Volume 12, Issue 4, pp 235-251
Date: 16 Aug 2012

Cost Effectiveness of Interferon-γ Release Assay for Tuberculosis Contact Screening in Japan

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Abstract

Background: Nearly the entire population of Japan has been vaccinated with Bacillus Calmette-Guerin (BCG), which causes a false-positive result in the tuberculin skin test (TST). The interferon-γ release assay QuantiFERON®-TB Gold (QFT) is a new alternative to the TST that can be used to screen for latent tuberculosis infection and active tuberculosis, as it has no cross-reactivity with BCG.

Methods: We constructed a Markov model to evaluate the cost effectiveness of the QFT for tuberculosis contact screening. The target population is a hypothetical cohort of 1000 immunocompetent 20-year-old individuals who have had contact with sputum-smear-positive pulmonary tuberculosis patients. The analysis was conducted from a societal perspective over the lifetime of a contact. We compared the QFT-alone strategy with the TST followed by QFT (TST/QFT) strategy and the TST-alone strategy.

Results: In a base-case analysis, the QFT-alone strategy was dominant ($US471.54; 28.1099 quality-adjusted life-years [QALYs]), compared with the TST/QFT strategy ($US500.55; 28.1087 QALYs) and the TST-alone strategy ($US573.98; 28.1079 QALYs). The incremental cost-effectiveness ratio of the QFT-alone strategy was a cost saving of $US23 043.5/QALY gained compared with the TST/QFT strategy. On one-way sensitivity analysis, TST specificity and the prevalence of tuberculosis/latent tuberculosis infection affected the cost effectiveness. The probabilistic analysis showed that the QFT-alone strategy has a 95% chance of being cost effective at a threshold ratio of $US2.10/QALY gained, compared with the TST/QFT strategy.

Conclusion: The QFT-alone strategy is the most cost effective for tuberculosis contact screening in Japan.