Cost-effectiveness of interferon-gamma release assay screening for latent tuberculosis infection treatment in Germany

Chest. 2007 May;131(5):1424-34. doi: 10.1378/chest.06-2728.


Objectives: To assess the cost-effectiveness of the new QuantiFERON-TB Gold In-Tube (QFT-G) [Cellestis; Carnegie, VIC, Australia] assay for screening and treating of persons who have had close contact with tuberculosis (TB) patients and are suspected of having latent tuberculosis infection (LTBI) [hereafter called close-contacts] in Germany.

Methods: The health and economic outcomes of isoniazid treatment of 20-year-old close-contacts were compared in a Markov model over a period of 20 years, using two different cutoff values for the tuberculin skin test (TST), the QFT-G assay alone, or the QFT-G assay as a confirmatory test for the TST results.

Results: QFT-G assay-based treatment led to cost savings of $542.9 and 3.8 life-days gained per LTBI case. TST-based treatment at a 10-mm induration size cutoff gained $177.4 and 2.0 life-days gained per test-positive contact. When the cutoff induration size for the TST was reduced to 5 mm, the incremental cost-effectiveness ratio fell below the willingness-to-pay threshold ($30,170 per life-years gained) but resulted in unnecessary treatment of 77% of contacts owing to false-positive TST results. Combination with the 5-mm induration size TST cutoff value compared to the results of the QFT-G assay alone reduced the total costs per 1,000 contacts by 1.8% to $222,869. The number treated to prevent 1 TB case was 22 for the two QFT-G assay-based procedures, 40 for the TST at a cutoff induration size of 10 mm, and 96 for the TST at a cutoff induration size of 5 mm. When the sensitivity rates of the TST and the QFT-G assay were compounded, the QFT-G assay strategy alone was slightly less costly (0.6%) than the two-step approach.

Conclusions: Using the QFT-G assay, but especially combining the QFT-G assay following the TST screening of close-contacts at a cutoff induration size of 5 mm before LTBI treatment is highly cost-effective in reducing the disease burden of TB.

Publication types

  • Comparative Study

MeSH terms

  • Adult
  • Antitubercular Agents / therapeutic use
  • Carrier State / diagnosis
  • Cost-Benefit Analysis / statistics & numerical data
  • False Positive Reactions
  • Female
  • Germany
  • Humans
  • Interferon-gamma / blood*
  • Isoniazid / therapeutic use
  • Male
  • Markov Chains
  • Mass Screening / economics*
  • Mass Screening / methods
  • Models, Theoretical*
  • Sensitivity and Specificity
  • Tuberculin Test / economics*
  • Tuberculin Test / methods
  • Tuberculosis / diagnosis*
  • Tuberculosis / drug therapy*


  • Antitubercular Agents
  • Interferon-gamma
  • Isoniazid