December 29, 2016
3 min read

Researchers warn of epidemic of drug-resistant TB in India

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Based on their modelling study, researchers predict that India will experience an epidemic of drug-resistant tuberculosis in the next two decades if changes are not made to the way patients are managed in the public and private sectors.

India already has the highest estimated number of patients with tuberculosis and multidrug-resistant tuberculosis in the world, Dick Menzies, MD, of the respiratory epidemiology and clinical research unit at McGill University, and colleagues noted. They estimate only minor changes in overall risk for infection, incidence, or prevalence of TB in India over 20 years under current practices.

“However, if these practices are not corrected, we project the tuberculosis epidemic will shift gradually from one that is predominantly drug susceptible to one with increasing drug resistance,” they wrote in The Lancet Public Health. “In particular, multidrug-resistant tuberculosis in India will shift from being mainly acquired during treatment to being mainly acquired through primary transmission.”

A ‘complex’ system

Menzies and colleagues characterized India’s health care system as “complex” with at least three non-public sectors, including private allopathic providers, pharmacists and informal providers of Ayurveda and homeopathic treatments.

However, the public sector accounts for most of the multidrug-resistant tuberculosis infections in India because of the irregular adherence of patients treated with rifampicin and has the highest risk for acquired multidrug-resistant tuberculosis among all sectors, according to Menzies and colleagues.

“Correction of irregular adherence in patients treated in the public sector would have the largest effect on multidrug-resistant tuberculosis incidence,” they wrote. “In other sectors, increased completion of treatment by patients treated by private providers would reduce mortality and isoniazid resistance, but have little effect on multidrug-resistant tuberculosis incidence.

“The largest reduction of tuberculosis morbidity and mortality in patients treated by chemists, and by informal providers, would occur if these providers referred all patients with tuberculosis to public or private allopathic providers. However, if informal providers and chemists stopped treating patients with tuberculosis drugs (even non-standard treatment), there would be greater mortality with a small decrease in isoniazid resistance.”

Predicted surges

Focusing on both public and private sectors and assuming no changes in provider or patient behavior, Menzies and colleagues used a Markov model to analyze India’s tuberculosis epidemic, using 2012 as a base year and projecting epidemiological outcomes for 2032.

“This is the first study, to our knowledge, to examine the effect of tuberculosis management and patient adherence on emergence of drug resistance in all major health care sectors in India,” they wrote.

If tuberculosis management practices across sectors in India remain unchanged over the next 20 years, Menzies and colleagues predict the following surges:

  • 47% increase in the incidence of isoniazid resistance;
  • 152% increase in multidrug-resistant tuberculosis incidence;
  • 242% increase in prevalent untreated multidrug-resistant tuberculosis; and
  • 275% increase in the risk for multidrug-resistant tuberculosis infection.

Further, they estimate that 85% of multidrug-resistant tuberculosis will be primary multidrug-resistant tuberculosis by 2032 compared with 15% in 2012.

Menzies and colleagues said potential interventions include scaling up effective public–private strategies to improve tuberculosis management, implementing local initiatives to increase tuberculosis case notification from private and informal sectors to ensure diagnosed patients receive appropriate treatment, and introducing patient-centered strategies such as reminder systems to improve treatment adherence.

“Evidence-based strategies to improve provider practices and patient adherence, and ultimately reduce the burden of drug-resistant tuberculosis in all relevant health sectors are urgently needed,” they concluded.

David Dowdy
David W. Dowdy

In a related editorial, Anthony T. Fojo, MD, of the Johns Hopkins School of Medicine, and David W. Dowdy, MD, associate professor in the Johns Hopkins Bloomberg School of Public Health, said an increase in multidrug-resistant tuberculosis incidence has never been seen on a scale as large as the one presented by Menzies and colleagues.

“China, for example, has an estimated multidrug-resistant tuberculosis prevalence nearly twice the global average, but this has been seen on a regional level for many years, with no clear evidence of a recent increase,” they wrote. “India — with its strong private sector involvement — might have epidemiological reasons to experience a larger increase in multidrug-resistant tuberculosis over the coming 20 years. But such a substantial shift has not yet occurred despite decades of treating tuberculosis with rifampin and isoniazid, and would be unprecedented outside the prison system of the former Soviet Union.” – by Gerard Gallagher

Disclosures: Please see the full study for a list of all authors’ relevant financial disclosures.