TUESDAY, Nov. 27, 2001 (HealthDayNews) -- The initial effectiveness of anti-HIV drugs doesn't appear to hinge on how much virus is in the bloodstream as long as the patient's immune system is even modestly active when treatment starts, two new studies say.
The findings should help doctors fine-tune their treatment of HIV, which causes AIDS. They also suggest that delaying treating HIV-positive patients with antiviral drugs may be safe, provided the patients are not at serious risk of developing AIDS. Delaying treatment could safely postpone the medications' serious side effects and their harsh impact on quality of life. The research appears in the Nov. 28 issue of the Journal of the American Medical Association.
The Centers for Disease Control and Prevention (CDC) estimates that 800,000 to 900,000 Americans are infected with HIV, including roughly 320,000 who have full-blown AIDS. As many as a third of HIV patients don't know they have the virus.
Since the advent of antiretroviral therapy (ART), including protease inhibitors that suppress HIV, doctors have recommended starting the drugs quickly to avoid spikes in viral levels.
The treatment philosophy "used to be to treat hard and treat early," says Dr. Roger Pomerantz, an AIDS expert at Thomas Jefferson University, in Philadelphia. "The pendulum is now swinging even farther the other way. You can wait a fair amount of time" before starting the drug regimen, says Pomerantz, author of an editorial accompanying the journal articles.
How many weeks, months or even years treatment can wait will vary from patient to patient, he says.
Last year, the International AIDS Society and the U.S. Public Health Service issued guidelines calling for HIV treatment to start when a patient's viral load topped 50,000 copies per milliliter of plasma or when the CD4 lymphocyte count, another marker of immune health, fell below 350 per microliter of blood. Pomerantz says the new research pushes the CD4 bar to as low as 200, a red flag for impending AIDS, as long as doctors carefully monitor their patients for further falloff in the protective immune cells.
In the first study, a team led by Dr. Andrew Phillips of Royal Free and University College Medical School, in London, followed 3,226 patients undergoing HIV treatment at European clinics between 1996 and 2000. None of the patients had received earlier therapy for their infection before starting the antiviral drug "cocktails," which included at least three medications.
After 32 weeks of treatment, the researchers say, 2,741 (85 percent) of the patients had viral counts driven below 500 copies per milliliter of plasma, a level at which therapy was considered successful. While people with 100,000 or more virus copies per milliliter got to 500 slower, the odds of reaching this milestone didn't depend on how much virus the patients initially had in their blood when they started drug therapy.
Patients with fewer CD4 cells at the start were more likely to die of AIDS and to suffer AIDS-related ailments, but these effects weren't especially strong. And baseline levels of neither measure predicted which patients would suffer a rebound in virus copies above the 500 mark.
The second study by researchers in British Columbia supports the European findings. That work looked at 1,219 patients with HIV receiving triple-drug therapy and found that higher viral loads did not increase the risk of treatment failure, the scientists say.
However, the Canadian researchers did find that patients with CD4 counts below 200 had sharply higher odds of dying of AIDS-related illnesses during the study than subjects with counts of 200 or better. Those with CD4 levels below 50 per microliter had nearly a seven-fold higher risk of death than patients above that cutoff, while patients whose cell counts fell between 50 and 199 faced a 3.4-fold higher risk.
So, if baseline virus and CD4 counts aren't clear-eyed oracles for treatment success, what, if anything, is?
"We know adherence is of key importance, but it is doubtful whether this knowledge can be used to predict the outcome of therapy before it is initiated," says Phillips in an e-mail interview.
While Pomerantz says the new work is "very important," he urges caution. It's possible, for example, that differences between initial virus and CD4 counts could emerge over time.
Dr. Robert Schooley, an AIDS researcher at the University of Colorado Health Sciences Center, in Denver, says the time issue is critical.
"We're still dealing with a middle check on a long-term disease," says Schooley. "Over the mid-to-short term, the reversibility of the immune damage is much better than we feared it might be. What you can't say is whether that holds for 20 years," he says.
What To Do: To learn more about the biology of HIV, try the University of California San Francisco. For more on AIDS, visit the CDC, or the World Health Organization.
