title: Cost-effectiveness of a new interferon-based blood assay, QuantiFERON-TB Gold, in screening tuberculosis contacts.
abstract: BACKGROUND
  Recent approval of interferon-gamma release assays that are more specific for Mycobacterium tuberculosis has given new options for the diagnosis of latent tuberculosis infection (LTBI).
  
  
  OBJECTIVE
  To assess the cost-effectiveness of Quanti-FERON-TB Gold (QFT-G) vs. the tuberculin skin test (TST) in diagnosing LTBI in contacts of active TB cases using a decision analytic Markov model.
  
  
  METHODS
  Three screening strategies--TST alone, QFT-G alone and sequential screening of TST then QFT-G--were evaluated. The model was further stratified according to ethnicity and bacille Calmette-Guérin (BCG) vaccination status. Data sources included published studies and empirical data. Results were reported in terms of the incremental net monetary benefit (INMB) of each strategy compared with the baseline strategy of TST-based screening in all contacts.
  
  
  RESULTS
  The most economically attractive strategy was to administer QFT-G in BCG-vaccinated contacts, and to reserve TST for all others (INMB CA$3.70/contact). The least cost-effective strategy was QFT-G for all contacts, which resulted in an INMB of CA$-11.50 per contact. Assuming a higher prevalence of recent infection, faster conversion of QFT-G, a higher rate of TB reactivation, reduction in utility or greater adherence to preventive treatment resulted in QFT-G becoming cost-effective in more subgroups.
  
  
  CONCLUSIONS
  Selected use of QFT-G appears to be cost-effective if used in a targeted fashion.
authors.affiliation: University of British Columbia, Vancouver, British Columbia, Canada. carlo.marra@ubc.ca
authors.forename: F
authors.initials: F
authors.lastname: Marra
authors.forename: C A
authors.initials: CA
authors.lastname: Marra
authors.forename: M
authors.initials: M
authors.lastname: Sadatsafavi
authors.forename: O
authors.initials: O
authors.lastname: Morán-Mendoza
authors.forename: V
authors.initials: V
authors.lastname: Cook
authors.forename: R K
authors.initials: RK
authors.lastname: Elwood
authors.forename: M
authors.initials: M
authors.lastname: Morshed
authors.forename: R C
authors.initials: RC
authors.lastname: Brunham
authors.forename: J M
authors.initials: JM
authors.lastname: Fitzgerald
mesh_terms: D000293:Adolescent; D000328:Adult; D001500:BCG Vaccine; D002170:Canada; D019411:Clinical Laboratory Techniques / Q000191:economics*; D016358:Contact Tracing; D003362:Cost-Benefit Analysis; D006801:Humans; D007371:Interferon-gamma / Q000097:blood; D008390:Markov Chains; D008875:Middle Aged; D012680:Sensitivity and Specificity; D014374:Tuberculin Test / Q000191:economics; D014376:Tuberculosis / Q000175:diagnosis*; D014611:Vaccination
chemical_list: D001500:BCG Vaccine; D007371:Interferon-gamma