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QFT-alone more cost-effective than TST-alone—in USA, UK, Germany, Canada and now Japan
A recently published Japanese study (Kowada et al 2008) has shown that QFT-alone is more cost-effective than TST followed by QFT and TST-alone for contact tracing.
The Markov model constructed in this study showed that the cost of the TST-alone strategy was very high because of unnecessary INH chemoprophylaxis being administered to a large number of individuals due to the poor specificity of the TST. In addition a higher adherence rate for INH and a lower adverse event rate to INH increased the cost effectiveness of the QFT- alone strategy compared with the TST followed by QFT strategy. Moreover, the QFT-alone strategy was shown to be more cost effective in individuals at high risk of tuberculosis mortality, such as the elderly.
This study supports assessments conducted in the US, UK, Canada and Germany—all of which showed that a QFT-alone approach is more cost- effective than a TST-alone approach. De Perio et al (2007) showed that QFT was more cost-effective for health care worker screening in a US setting, while Oxlade et al (2007) showed that, for Canadian contacts who were BCG vaccinated after infancy, QFT-alone was more cost-effective than TST-alone—because of the reduced specificity of the TST.
In assessments conducted in Germany (Diel et al 2007) and the UK (NICE), an IGRA-only approach was cheaper than a TST-only approach for contact tracing; however combining an IGRA with a TST (validation of a positive TST by QFT) was slightly cheaper again. However this approach raises ethical considerations as the TST can miss people who will later develop active TB, but would have been picked up had they been first tested with QFT (Diel et al 2008).
Additionally it requires the maintenance of two testing modalities and does not capture the operational advantages offered by QFT such as the need for a single visit and (in most cases) next day results.
To see a review of literature on economic assessments visit http://www.cellestis.com/IRM/Company/ShowPage.aspx?CPID=1534.
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