WEDNESDAY, Oct. 19 (HealthDay News) -- Three new studies provide insight into the best time to begin AIDS drug treatments in HIV-positive patients who are also infected with tuberculosis, a double whammy common in Africa. Starting the drugs earlier, even by a few weeks, could make a big difference for patients who are very sick, the research suggests.

The cost of earlier treatment isn't much higher, and the drugs pay big dividends, said Dr. Diane V. Havlir, lead author of one of the studies. Her study found that starting the drugs within two weeks of diagnosis rather than eight weeks reduced the death rate or progression to more severe HIV by almost 40 percent in the sickest patients.

"This is fabulous news. It's amazing that starting it at two weeks versus eight weeks makes such a difference," said Havlir, professor of medicine at the University of California, San Francisco, and head of the AIDS division at San Francisco General Hospital.

HIV, the virus that causes AIDS, and tuberculosis frequently strike people in less developed regions such as sub-Saharan Africa, Havlir said. HIV disrupts the immune system, she said, making it easier for people to get tuberculosis.

"These two diseases go hand in hand," she said. "They're synergetic, they're partners."

The studies are published in the Oct. 20 issue of the New England Journal of Medicine.

The HIV-tuberculosis combo is less common in richer areas of the world, such as the West, said Dr. Jeremy Farrar, co-author of a commentary accompanying the studies. He is director of the Oxford University Clinical Research Unit in Ho Chi Minh City, Vietnam.

It hasn't been clear how to treat patients who have both diseases. Among other things, doctors worried about adding HIV drugs to tuberculosis drugs because of concerns about side effects, including those from drug interactions, Havlir said.

The three new studies looked at the problem from different perspectives. In Havlir's study of 806 patients who were assigned to different treatments, 13 percent who received earlier HIV treatment got worse on the AIDS front or died within 48 weeks compared to 16 percent of those who started the drugs later.

But there was a much bigger difference in patients in the worst shape in terms of HIV: 16 percent of those who received earlier treatment got worse or died, compared to 27 percent of those who received later treatment.

The finding suggests that "very sick patients must be started (on HIV drugs) immediately and early," Havlir said, but those who are doing better can wait eight weeks.

Farrar supported the findings of the studies and agreed that it's a good idea to start HIV treatment early in the patients whose HIV is most severe. It will save lives and could reduce transmission, he said.

But culture tests for TB are rare in areas lacking state-of-the-art medical resources, so diagnoses are often based on clinical observation of symptoms, Farrar said. Also, he noted that most of the patients in the studies had pulmonary tuberculosis, which is rarely life-threatening. Death rates are much higher for more severe forms, such as tuberculous meningitis.

Farrar also acknowledged other caveats. A regimen of many pills might lead to noncompliance among some patients, he said. For patients with drug-resistant tuberculosis, the medication schedule is even more daunting.

The possibility also exists of "complex interactions between the drugs for TB and HIV and other conditions the patients have," he said.

"We need a much greater understanding of this interaction and work to help deliver these crucial drugs in a better way," Farrar stated.

More information

For more about tuberculosis, see the U.S. National Library of Medicine.