IIn one of the largest clinical trials of its kind, scientists have discovered HIV patients who use episodic drug treatment are more than twice as likely to die or develop an AIDS-related illness as those who take medications continuously.

Researchers from institutions all over the world, including the University, collaborated to track the progress of more than 5,000 HIV-positive volunteers from 33 different countries. The $73 million study, led and funded by the National Institutes of Health, was published Thursday in the New England Journal of Medicine.

Researchers found that a drug-conservation approach to HIV treatment, which some doctors have advocated to reduce drug side effects and costs, is both less effective and potentially much more harmful to patients than a continuous drug regimen, said Sandra Lehrman, director of the therapeutic research program in the National Institute of Allergy and Infectious Diseases’ AIDS division.

Participants were split into two groups. In one, doctors gave patients HIV-suppressing medication only when the health of their immune systems dipped below a certain level. The other group took the drugs continuously.

“No matter how you looked at it, the patients on interrupted therapy did less well than the people on continued therapy,” Lehrman said.

Although the trial was meant to determine whether one treatment was more hazardous for patients than the other, researchers were nonetheless surprised by the results, said Birgit Grund, a University professor of statistics and senior statistician for the study.

“What turned out to have happened was the treatment difference of relative risk was much higher than anticipated,” she said.

The risk was so much higher for people getting drug-interruption treatment, Grund said, that the study, which began in 2002 and was supposed to follow participants for an average of six years, ended after only four years. When researchers terminated the trial in January 2006, they had followed patients for an average of 16 months.

Andy Ansell, a health education coordinator for the Minnesota Aids Project, said he’s disappointed the study’s results weren’t more promising for patients looking for less debilitating, more cost-effective treatment. But he said he believes there is more research to be done.

“Obviously, it’s a setback,” he said. “But there are still places they can be looking in order to streamline treatment.”

Ansell, who was diagnosed with HIV 19 years ago, said he is currently on a continuous drug treatment program in which he takes four medications a day.

Since being diagnosed, Ansell has taken three breaks from treatment, he said, during which he didn’t take any medication at all in order to cleanse his body of the medications’ chemicals.

“The thing people don’t understand with these drugs is, while they are effective at stopping HIV from replicating itself, these compounds are very toxic to the body,” he said. “Anti-retroviral therapy is self-administered chemotherapy for the rest of a person’s life.”

So-called “drug holidays” are different than episodic drug treatment, Ansell said, which “basically boils down to a structured way to skip your doses.”