XDR-TB prevention starts with TB treatment

Washington -- The outlook for treating extensively drug-resistant tuberculosis turned gloomier with a new study that confirms earlier reports of the poor prognosis associated with the disease.

The study, the largest to date on the most lethal form of TB, determined that patients with XDR-TB are four times more likely to fail treatment and three times more likely to die than are patients with other strains of multidrug-resistant TB. The study was in the Nov. 15 American Journal of Respiratory and Critical Care Medicine, a journal of the American Thoracic Society.

Despite efforts to control all forms of TB, the disease remains the worldwide leading cause of death from an infectious agent. An estimated 8 million to 9 million new cases develop annually and 2 million patients die, the study authors noted.

As drug-resistant cases increase, physicians find treatment options limited. An editorial in the same journal issue raised a related concern. Does the rise of XDR-TB portend the reversal of progress made at combating TB? The high mortality rate for XDR-TB mirrors TB deaths of decades ago, before there were any drugs, said editorial co-author D'Arcy Richardson, RN, technical director for TB programs at PATH, a nonprofit, international global health organization. "We are looking at, more or less, the natural history of TB."

For their study, "Treatment Outcomes and Long-term Survival in Patients with Extensively Drug-resistant Tuberculosis," researchers reviewed medical records of 1,407 patients in South Korea who were diagnosed with resistant forms of TB between 2000 and 2002, and 75 patients who had XDR strains.

Researchers monitored patients for up to seven years after treatment began. Among the findings: XDR-TB patients were older than MDR-TB patients, more likely to have a history of treatment with second-line TB drugs and more likely to have a history of being treated for TB two or more times.

"One of the most important take-away messages ... is to treat TB carefully the first time around so you don't end up with multidrug-resistant or extensively drug-resistant TB," Richardson said.