Mortality Reduced by DNA Test for Tuberculosis

A rapid molecular test for tuberculosis (TB) could substantially and cost-effectively reduce deaths from the disease and improve treatment in southern Africa.

An automated DNA test can show a result within two hours for people at high risk of multidrug resistant TB and also human immunodeficiency virus (HIV)-associated TB and many countries are already moving to adopt the test.

Scientists at the Harvard School of Public Health (Boston, MA, USA) investigated the potential health and economic consequences of implementing the Xpert TB test in Botswana, Lesotho, Namibia, South Africa, and Swaziland. The Xpert test enables rapid detection of Mycobacterium tuberculosis and rifampicin drug resistance (MTB/RIF). The World Health Organization (Geneva, Switzerland) recommends Xpert for initial diagnosis in individuals suspected of having multidrug-resistant TB (MDR-TB) or HIV-associated TB.

The investigator found that replacing the current diagnostic approach, which relies on identifying the bacteria in patient's sputum using a microscope, with one based on the Xpert test would prevent an estimated 132,000 TB cases and 182,000 TB deaths in southern Africa over 10 years, reducing by 28% the proportion of the population with active TB. The new test provides information on TB drug resistance; many more patients would be referred for treatment of multidrug resistant TB, which is expensive in this setting. The additional HIV treatment costs are a result of the success of the intervention, as individuals co-infected with TB and HIV receive better TB care, their survival improves, increasing the total number of people receiving HIV treatment.

The scientists found that the cost per year of healthy life gained from adopting the new test ranged from USD 792 in Swaziland to USD 1,257 in Botswana. While these results suggest that scaling up Xpert can be a good health investment, the cost per healthy year gained is substantially higher in this study than in previous reports, and the economic results raise questions about affordability that will be critical for policy makers to consider. The Xpert MTB/RIF test is a product of Cepheid (Sunnyvale, CA, USA) and runs on their GeneXpert System.

Nicolas Menzies, a PhD candidate in health policy at Harvard School of Public Health, and lead author of the study said, "This test is one of the most significant developments in TB control options in many years. Our study is the first to look at the long-term consequences of this test when incorporated into routine health programs." The study appeared online on November 20, 2012, in journal Public Library of Science (PLOS) Medicine.

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Harvard School of Public Health
World Health Organization
Cepheid