title: Systematic review of cost and cost-effectiveness of different TB-screening strategies.
abstract: BACKGROUND
  Interferon-γ release assays (IGRAs) for TB have the potential to replace the tuberculin skin test (TST) in screening for latent tuberculosis infection (LTBI). The higher per-test cost of IGRAs may be compensated for by lower post-screening costs (medical attention, chest x-rays and chemoprevention), given the higher specificity of the new tests as compared to that of the conventional TST. We conducted a systematic review of all publications that have addressed the cost or cost-effectiveness of IGRAs. The objective of this report was to undertake a structured review and critical appraisal of the methods used for the model-based cost-effectiveness analysis of TB screening programmes.
  
  
  METHODS
  Using Medline and Embase, 75 publications that contained the terms "IGRA", "tuberculosis" and "cost" were identified. Of these, 13 were original studies on the costs or cost-effectiveness of IGRAs.
  
  
  RESULTS
  The 13 relevant studies come from five low-to-medium TB-incidence countries. Five studies took only the costs of screening into consideration, while eight studies analysed the cost-effectiveness of different screening strategies. Screening was performed in high-risk groups: close contacts, immigrants from high-incidence countries and healthcare workers. Two studies used the T-SPOT.TB as an IGRA and the other studies used the QuantiFERON-TB Gold and/or Gold In-Tube test. All 13 studies observed a decrease in costs when the IGRAs were used. Six studies compared the use of an IGRA as a test to confirm a positive TST (TST/IGRA strategy) to the use of an IGRA-only strategy. In four of these studies, the two-step strategy and in two the IGRA-only strategy was more cost-effective. Assumptions about TST specificity and progression risk after a positive test had the greatest influence on determining which IGRA strategy was more cost-effective.
  
  
  CONCLUSIONS
  The available studies on cost-effectiveness provide strong evidence in support of the use of IGRAs in screening risk groups such as HCWs, immigrants from high-incidence countries and close contacts. So far, only two studies provide evidence that the IGRA-only screening strategy is more cost-effective.
authors.affiliation: University Medical Center Hamburg-Eppendorf, Institute for Health Service Research in Dermatology and Nursing - Hamburg, Germany. a.nienhaus@uke.uni-hamburg.de
authors.forename: Albert
authors.initials: A
authors.lastname: Nienhaus
authors.forename: Anja
authors.initials: A
authors.lastname: Schablon
authors.forename: José Torres
authors.initials: JT
authors.lastname: Costa
authors.forename: Roland
authors.initials: R
authors.lastname: Diel
mesh_terms: D016358:Contact Tracing / Q000191:economics / Q000379:methods; D003362:Cost-Benefit Analysis; D005260:Female; D005858:Germany; D017048:Health Care Costs; D006801:Humans; D059425:Interferon-gamma Release Tests / Q000191:economics* / Q000379:methods; D008297:Male; D008403:Mass Screening / Q000191:economics* / Q000379:methods*; D014374:Tuberculin Test / Q000191:economics / Q000379:methods; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000191:economics / Q000453:epidemiology