New, shorter therapies to treat tuberculosis more effective

New, shorter therapies to treat tuberculosis (TB), which kills millions worldwide each year, may make TB control efforts substantially more effective by simplifying treatment, improving patient outcomes and reducing transmission of new infections.

Looking at the potential benefits if a two-month regimen becomes available during the next decade, a new study led by researchers at the Harvard School of Public Health (HSPH) reports that as many as 11 million cases and 5 million deaths could be averted through 2030 in the South-East Asia region alone, compared to a situation in which treatment continues at current levels with existing drug regimens. The research appears in the August 2006 online edition of Public Library of Science Medicine.

Every year, some eight or nine million people develop active TB and some two million people die from the disease. The cornerstone of global control efforts is the World Health Organization's DOTS strategy, which relies on four or more drugs administered under the observation of health care workers for at least six months. No new first-line TB drugs have been developed in over 30 years, but recently an array of promising new drug candidates have been identified, which raises hopes that novel, shorter regimens may enter the TB treatment arsenal in the coming years.

Exploring a number of different scenarios, the researchers developed a mathematical model of TB to study what impact shortening treatment durations might have on the course of the epidemic. The results showed that shorter regimens could produce dramatic benefits at the population level by reducing patients' opportunities to default from treatment and therefore improving their own outcomes as well as curtailing transmission to others. Other possible indirect benefits were explored in alternative scenarios in which new regimens are accompanied by wider case detection, which might arise if shorter therapies can free up scarce financial and human resources, simplify program administration and patient monitoring and prompt more people to seek care.

Applying the model to the South-East Asia region, where around one-third of global cases and deaths occur, the researchers found that a two-month regimen introduced by 2012 could double or even triple the current rates of decline in new cases and deaths, which would translate into total reductions between 2012 and 2030 of up to 40 percent of the numbers expected with continuing use of current drugs. However, the study cautions that if the introduction of new drugs is delayed by ten years, nearly three-fourths of this benefit would be erased.

Joshua Salomon, assistant professor of international health at HSPH and lead author of the study, said, "Even in optimistic scenarios where current efforts expand dramatically, there is enormous potential to enhance global TB control with new technologies. Continued progress against TB will require aggressive efforts to develop new, effective and affordable drugs in parallel to the ongoing campaign to expand the reach of current control strategies."