Cost effectiveness of interferon-gamma release assay for tuberculosis contact screening in Japan.
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-gamma 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 ($US 471.54; 28.1099 quality-adjusted life-years [QALYs]), compared with the TST/QFT strategy ($US 500.55; 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.


CONCLUSIONS
The QFT-alone strategy is the most cost effective for tuberculosis contact screening in Japan.
Kowada
Akiko
A
Katsushika City Public Health Center, Tokyo, Japan. a-kowada@city.katsushika.lg.jp
Takahashi
Osamu
O
Shimbo
Takuro
T
Ohde
Sachiko
S
Tokuda
Yasuharu
Y
Fukui
Tsuguya
T
D000328:Adult; D000368:Aged; D000995:Antitubercular Agents / Q000627:therapeutic use; D001500:BCG Vaccine / Q000191:economics*; D002353:Carrier State / Q000175:diagnosis; D016358:Contact Tracing; D003362:Cost-Benefit Analysis; D005189:False Positive Reactions; D006801:Humans; D007371:Interferon-gamma / Q000097:blood*; D008390:Markov Chains; D008403:Mass Screening / Q000191:economics* / Q000379:methods; D008875:Middle Aged; D008962:Models, Theoretical; D012680:Sensitivity and Specificity; D014374:Tuberculin Test / Q000191:economics* / Q000379:methods; D014376:Tuberculosis / Q000175:diagnosis* / Q000188:drug therapy
D000995:Antitubercular Agents; D001500:BCG Vaccine; D007371:Interferon-gamma