"We found that using a therapy of four months of Rifampin instead of the current nine months of Isoniazid costs significantly less for the health-care system," lead analyst Anne Aspler, of the respiratory epidemiology and clinical research unit at McGill University's Montreal Chest Clinic, said in a prepared statement.

"Overall, Rifampin costs about $484 less per patient treated, which, if we assume that four months of Rifampin has a least equal efficacy to nine months of Isoniazid, represents an added savings to the health system of more than $10,000 per patient prevented from developing [full-blown] TB disease. And because of improvements in compliance, we are actually preventing more cases. This treatment can save money as well as lives," Aspler said.

The study was expected to be presented Tuesday at the American Thoracic Society's International Conference, in Toronto.

Currently, about 2 billion people worldwide are believed to have latent, or dormant, TB. Of those, 8 million to 9 million will develop TB each year, and 1.6 million of them will die.

TB is most prevalent in developing countries, where Rifampin is offered at a subsidized cost through the Global Drug Facility of the World Health Organization. Not only is Rifampin less expensive, it has better patient compliance than Isoniazid due to the shorter treatment time, according to Aspler.

"While Isoniazid therapy is 90 percent effective for those who complete it, in reality, fewer than 50 percent do," Aspler said. This low compliance rate can have serious health consequences for patients who fail to complete treatment and for those they later infect.

Previous research and experience suggests that a four-month treatment program improves patient compliance by 20 percent to 25 percent, and reduces the risk of serious side effects such as liver damage.

"The next step in research is a major phase III clinical trial of efficacy — ideally in HIV-infected and non-infected patients and in low-income settings where tuberculosis is the leading cause of death in people living with HIV," Aspler said.

— Robert Preidt

SOURCE: American Thoracic Society, news release, May 20, 2008