Costs and consequences of using interferon-γ release assays for the diagnosis of active tuberculosis in India
Abstract
Background
There is growing concern that interferon-γ release assays (IGRAs) are being used off-label for the diagnosis of active tuberculosis (TB) disease in many high-burden settings, including India, where the background prevalence of latent TB infection is high. We analyzed the costs and consequences of using IGRAs for the diagnosis of active TB in India from the perspective of the Indian TB control sector.
Methods and Findings
We constructed
a decision analytic model to estimate the incremental cost and
effectiveness of IGRAs for the diagnosis of active TB in India.
We compared a reference scenario of clinical examination and
non-microbiological tests against scenarios in which clinical
diagnosis was augmented by the addition of either sputum smear
microscopy, IGRA, or Xpert MTB/RIF. We examined costs (in 2013
US dollars) and consequences from the perspective of the Indian
healthcare sector. Relative to sputum smear microscopy, use of
IGRA for active TB resulted in 23,700 (95% uncertainty range,
UR: 3,800 – 38,300) additional true-positive diagnoses,
but at the expense of 315,700 (95% UR: 118,300 – 388,400)
additional false-positive diagnoses and an incremental cost of
US$49.3 million (95% UR: $34.9 – $58.0 million) (2.9
billion Indian Rupees). Relative to Xpert MTB/RIF (including the
cost of treatment for drug resistant TB), use of IGRA led to 400
additional TB cases treated (95% UR: [-8,000] – 16,200),
370,600 (95% UR: 252,200 – 441,700) more false-positive
diagnoses, 70,400 (95% UR: [-7,900] – 247,200) fewer
disability-adjusted life years averted, and US$14.6 million
(95%UR: [-$7.2] – $28.7 million) (854 million Indian
Rupees) in additional costs.
Conclusion
Using IGRAs for diagnosis
of active TB in a setting like India results in tremendous
overtreatment of people without TB, and substantial incremental
cost with little gain in health. These results support the
policies by WHO and Standards for TB Care in India, which
discourage the use of IGRAs for the diagnosis of active TB in
India and similar settings.
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Source:
PLOS ONE
