Inaccurate TB blood tests commonplace in many TB high-burden countries

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Although recent press attention has highlighted the problematic use of TB serological tests by medical providers in India, a new paper in The European Respiratory Journal (Widespread use of serological tests for tuberculosis: data from 22 high-burden countries) demonstrates that the use of these tests is much wider spread.

Various TB serologic tests.

Drs. J. Grenier and M. Pai conducted a survey of both the private and public health sectors in the 22 high burden TB countries and found that use of these costly and inaccurate diagnostic tests is commonplace in many of these countries, despite World Health Organization (WHO) guidance discouraging their use and country policies that in many instances do not authorize their use.

“It is worrisome than 17 of 22 highest TB burden countries have these assays on the market. In countries such as India, these tests are very widely used in the private health sector,” said author Madhukar Pai, MD, PhD of McGill University in Montreal.  Eleven (65 percent) of the 17 countries reported that serological tests were used to initiate therapy for active TB, including India, Indonesia and South Africa who reported that this happened “often” in the private sector.  Serological testing was also especially widespread in China, Indonesia, Pakistan, Vietnam and Uganda.

“The apparent popularity of these inaccurate antibody tests raises interesting questions: What are the market dynamics that allow bad tests to succeed in the market, while good technologies sometimes struggle to get scaled-up? And what is the best business model to replace bad tests with validated, WHO-endorsed technologies?,” Pai said

The authors argue that high burden countries must implement WHO policy, tighten their regulations and educate doctors, laboratories and consumers, while providing incentives to the private sector to use validated, WHO-endorsed products instead of serological tests.

In another article by S. Jaroslawski and Pai, published in The Journal of Epidemiology and Global Health, the authors explore why these serological tests are so popular in the private healthcare sector in India. Seven root causes were identified, including poor regulation of TB tests in the private health sector, the high costs of molecular and liquid culture tests, and the limitations of smear microscopy.

The Indian government is taking action, according to The Times of India, and is set to place a ban on the sale and use of these serological tests.

“The big challenge for India now is to wean doctors and laboratories away from inaccurate TB tests, and replace them with validated WHO-endorsed tests such as GeneXpert MTB/RIF [rapid TB diagnostic test] and liquid culture,” Pai said. “This will require market-based business models which will actually work within the private sector in India.”

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