Costs and Consequences of Using Interferon-γ Release Assays for the Diagnosis of Active Tuberculosis in India
Fig 1
Decision Analytic Model for IGRA Testing for Active TB in India.
A simplified schematic of the decision analytic model of one million TB suspects in India, with branches for the reference scenario (clinical exam only, no microbiological testing), reference scenario + testing with interferon-gamma release assays (“IGRA”), clinical exam + sputum smear microscopy (“Sputum Smear”), and clinical exam + testing with Xpert MTB/Rif with MDR treatment (“Xpert MTB/RIF”). Differential infectiousness (as denoted by smear status, in the event that a smear could be performed) is incorporated into the model, as are the reference set of tests, but these are not shown for simplicity. * “Costs” includes the cost of empiric treatment and the cost of the reference test(s), as well as the cost of the microbiological testing and TB treatment (if applicable). The “Xpert MTB/RIF” also includes the cost of MDR-TB treatment. Consequences include deaths, DALYs, secondary cases, false-positives treated, and true positives treated.