Enhanced cost-benefit analysis of strategies for LTBI screening and INH chemoprevention in Germany.

OBJECTIVES: There is only limited economic data in head-to head comparison between a whole blood QuantiFERON TB Gold in tube (QFT) and the tuberculin skin test (TST) when screening and treating for latent tuberculosis infection (LTBI), and no published study to date that takes into account the predictive value of the two tests.
METHODS: Health and economic outcomes of isoniazid preventive treatment (IPT) of close contacts were compared in a decision tree model to perform a cost-benefit analysis with respect to isoniazid related hepatotoxicity and early post-exposure TB over a 2-y period, using the QFT or TST alone or QFT as a confirmatory test for TST results.
RESULTS: Cost of screening and treating for using the QFT alone amounted to euro215.79 per close contact, less than that of dual step-testing (euro227.89) or using TST alone (euro232.58). Savings amounted to euro12,200 or euro16,791 per 1000 close contacts, respectively. QFT based procedures were most sensitive to low compliance with IPT or increasing price. Costs of dual step screening was mostly influenced by cost of treating TB disease. When the progression rate for QFT was lowered to that for the TST in a sensitivity analysis, the relationship between the strategies remained robust. In addition, costs of the QFT strategy decreased to euro165.1, and those of the dual step strategy to euro218.4.
CONCLUSION: IPT on the basis of using the QFT assay alone produces less cost and reduces more TB cases than other strategies in a low-incidence setting. These data have implications for the rational implementation of screening strategies in contact investigation.