Cost effectiveness of interferon-γ release assay for tuberculosis contact screening in Japan

Background: Nearly the entire Population of Japan has been vaccinated with Bacillus CalmetteGuerin (BCG) Which Causes a false-positive result in the tuberculin skin test (TST). The interferon-gamma release assay QuantiFERON (R)-TB Gold (QF-T) 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 evalute 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 QFF-alone strategy with the TST followed by QFT (TST/QFT) strategy and the TST-alone strategy. Results: In a base-case analysis, the QFF-alone strategy was dominant ($US471.54; 28.1099 quality-adjusted life-years [QALYs]), compared with the TST/QF17 strategy ($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/QFF strategy. On one-way sensitivity analysis, TST specificity and the prevalence of tuberculosus/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.