TB Diagnosis: Rollout Strategy As Important As New Tests

A study shows that improving the doctor referral network could have just as much impact on TB as implementing expensive new testing.

AsianScientist (Jul 22, 2014) – A study suggests that getting patients in India quickly evaluated by the right doctors can be just as effective at curbing tuberculosis (TB) as a new, highly accurate screening test. The results of the study have been published in the journal PLoS Medicine.

While ideally all suspected TB cases would be evaluated with the new test, it is primarily being used only on the highest-risk populations and only in public health clinics, partly because of its cost and the complexity of the nation’s health care system. This slows diagnosis of a disease that must be caught early, the researchers say.

Approximately 8.6 million people worldwide develop active TB each year, and 1.4 million die from it. India alone accounts for twenty five percent of all diagnosed TB patients. Although treatment for TB is freely available and highly effective, TB continues to kill hundreds of thousands of people every year in India, and vast numbers of cases go undetected. Public TB clinics are better equipped to quickly diagnose and begin treatment for the disease, but patients are often reluctant to utilize them. The researchers say that for better TB tests to make a major difference they must be made available to the private health care providers where patients first seek care.

“Most people in India with underlying TB initially seek care for cough from the private health care sector,” notes the study’s lead author Dr. Henrik Salje, a postdoctoral fellow at the Johns Hopkins Bloomberg School of Public Health. “Private providers often use the wrong tests for TB, and without getting the right diagnosis, patients move between providers with long diagnostic delays.”

Often, patients with symptoms start with convenient and more trusted private sector physicians and informal health care providers, but ultimately public sector physicians diagnose and treat more than half of the TB cases in India. They have long used sputum smear microscopy, which may miss up to half of all active cases.

The new test for TB, Xpert MTB/RIF, can diagnose TB in 90 minutes, capture 70 percent of cases missed by microscopy and can also determine if the strain is resistant to rifampin, the most important anti-TB drug. India has begun rolling out this new technology, but since Xpert MTB/RIF is much more expensive than traditional tests, it is currently being implemented mainly in public clinics to test HIV-positive patients who may also have TB or those at high risk of having multidrug-resistant tuberculosis (MDR-TB).

For their study, the researchers explored the impact of six different rollout strategies by developing a mathematical model of TB transmission, care-seeking and diagnostic and treatment practices in India. They found that providing access to Xpert for 20 percent of all individuals seeking care for TB symptoms could reduce new TB cases by 14.1 percent over five years, while the “high-risk-only,” public-sector strategy currently being implemented might only reduce TB cases by 0.2 percent. However, achieving this result required substantially more resources and appropriate TB treatment. The authors also found that simply improving the referral network of informal providers to the public sector—without any new testing at all—could have as much of an effect on TB as scaling up the new Xpert test.

“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,” says the study’s senior author Dr. David W. Dowdy, an assistant professor in the Department of Epidemiology. “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.”

The article can be found at: Salje et al. (2014) The Importance of Implementation Strategy in Scaling Up Xpert MTB/RIF for Diagnosis of Tuberculosis in the Indian Health-Care System: A Transmission Model.

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Source: John Hopkins University Bloomberg School of Public Health; Photo: Yale Rosen/Flickr/CC.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

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