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Xpert test could substantially reduce TB burden in India
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The public health impact of the Xpert test for tuberculosis in India depends heavily on its broader use in the private and public health sectors, as well as the quality of care after diagnosis, according to new data published in PLOS Medicine.
In India, the Xpert MTB/RIF test (Cepheid) test is primarily being used for those with HIV or at highest risk for multidrug-resistant TB in the public sector. For the rapid diagnostic test to have a more substantial effect, researchers said it must be made available to private health care providers as well.
“Most people in India with underlying TB initially seek care for cough from the private health care sector,” Henrik Salje, PhD, a postdoctoral fellow at Johns Hopkins Bloomberg School of Public Health, said in a press release. “Private providers often use the wrong tests for TB, and without getting the right diagnosis, patients move between providers with long diagnostic delays.”
Henrik Salje
Salje and colleagues developed a mathematical model of TB transmission, care-seeking behavior and diagnostic and treatment practices in India, and evaluated the public health impact of several different strategies to rolling out the Xpert test.
They found that providing the test to 40% of public-sector patients with HIV or prior TB treatment — similar to the current national strategy in India — would only reduce TB incidence by 0.2% (95% uncertainty range [UR], –1.4 to 1.7) and MDR-TB incidence by 2.4% (95% UR, –5.2 to 9.1). In comparison, making the test available to patients in the public sector without HIV or prior treatment in addition to 20% of all private-sector providers, including qualified and unqualified personnel, could reduce new TB cases by 14.1% after 5 years (95% UR, 10.6-16.9). However, this strategy relies on diagnosed patients also receiving appropriate treatment and requires more than 2,200 new Xpert systems.
The researchers also found that simply improving referrals could successfully reduce the incidence of TB in India — even without the use of new diagnostics. For example, if 20% of all individuals seeking care for TB symptoms from providers with no formal medical training were referred to smear-based TB diagnosis in the public sector without any use of Xpert, TB incidence would be reduced by 6.3%.
David W. Dowdy
“The impact of better TB diagnosis depends not only on the accuracy of the test, but also on the behavior of both patients and providers, good access to validated new tools, and quality TB treatment following diagnosis,” study researcher David W. Dowdy, MD, PhD, assistant professor in the department of epidemiology at Johns Hopkins, said in the release. “To achieve maximum impact of novel diagnostics, India should engage the private sector, improve quality of care across all sectors, and dramatically increase the resources used to fight TB.”
David W. Dowdy, MD, PhD, can be reached at 615 N. Wolfe St., E6531, Baltimore, Md. 21205; Email: ddowdy1@jhmi.edu.
Disclosure: The researchers report no relevant financial disclosures.
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