Cost-effectiveness of interferon gamma release assays vs tuberculin skin tests in health care workers.
BACKGROUND
Interferon gamma release assays (IGRAs) offer alternatives to tuberculin skin tests (TSTs) for diagnosing latent tuberculosis infection (LTBI). Unlike TSTs, IGRAs require only a single patient visit and are not affected by prior BCG vaccination, providing greater specificity. Of 2 Food and Drug Administration-approved IGRAs, the newer QuantiFERON-TB Gold in Tube test (QFT-GIT) requires less manual processing time than the QuantiFERON-TB Gold test (QFT-G). We compared the cost-effectiveness of the QFT-G, QFT-GIT, and TST for detecting LTBI in new health care workers (HCWs).


METHODS
A Markov state-transition decision analytic model using the societal perspective and lifetime horizon was constructed to compare costs and quality-adjusted life-years (QALYs) associated with the 3 strategies for hypothetical 35-year-old HCWs with or without prior BCG vaccination. Direct and indirect costs and probabilities were based on manufacturer data, national Veterans Health Administration records, and the published literature. Future costs and QALYs were discounted at 3% per year.


RESULTS
Both IGRAs were more effective and less costly than the TST, whether or not the HCW had been vaccinated with BCG previously. The incremental cost-effectiveness ratio of the QFT-G compared with the QFT-GIT was $14,092/QALY for non-BCG-vaccinated HCWs and $103,047/QALY for BCG-vaccinated HCWs. There was no prevalence of LTBI at which the TST became the most effective or least costly strategy. If the sensitivity of the QFT-GIT exceeds that of the QFT-G, then the QFT-GIT is the most effective and least costly strategy.


CONCLUSIONS
Use of the QFT-G and QFT-GIT leads to superior clinical outcomes and lower costs than the TST and should be considered in screening non-BCG-vaccinated and BCG-vaccinated new HCWs for LTBI.
de Perio
Marie A
MA
Division of Infectious Diseases, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Box 670560, Cincinnati, OH 45267, USA. deperiom@hotmail.com
Tsevat
Joel
J
Roselle
Gary A
GA
Kralovic
Stephen M
SM
Eckman
Mark H
MH
D000942:Antigens, Bacterial; D003362:Cost-Benefit Analysis; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006282:Health Personnel; D006801:Humans; D007371:Interferon-gamma / Q000097:blood* / Q000378:metabolism; D007962:Leukocytes / Q000378:metabolism; D008297:Male; D008403:Mass Screening; D012680:Sensitivity and Specificity; D014374:Tuberculin Test / Q000191:economics*; D014376:Tuberculosis / Q000175:diagnosis* / Q000191:economics
D000942:Antigens, Bacterial; D007371:Interferon-gamma