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78% of U.S. HIV Infections Drug Resistant

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WebMD Health News
Reviewed by Gary D. Vogin, MD

Dec. 18, 2001 -- At least one AIDS drug no longer works for the vast majority of Americans living with HIV.

Used in combination, the drugs are a lifeline. Now a nationwide study shows that many people may be reaching the end of that line.

"It does mean patients are running out of options," study co-leader Samuel A. Bozzette, MD, PhD, tells WebMD. "And more are going to be out of options soon."

Reported at the American Society for Microbiology's annual infectious disease conference, the findings paint a grim picture. They show that 78% of Americans being treated for HIV infection carry a virus that already is resistant to one or more anti-HIV drugs.

"Treatment of HIV is going to be increasingly complicated," says Bozzette, a researcher at the University of California, San Diego, and the VA San Diego Healthcare System.

That's bad news for doctors, already faced with an extremely complex situation. There now are 16 different FDA-approved drugs that fight the AIDS virus. They fall into three basic classes: nucleoside- and non-nucleoside-based reverse transcriptase inhibitors (NRTIs and NNRTIs) and protease inhibitors (PIs). A virus resistant to one drug often -- but not always -- is resistant to some or all of the other drugs in its class.

The drugs must be used in combinations. People who begin treatment must continue for the rest of their lives. Some combinations work for some people, and some don't. There is no easy way to tell which drugs to start with -- or which drugs to switch to if the first combination fails.

Studies suggest that one in five newly detected U.S. HIV infections already is resistant to at least one anti-HIV drug. Doctors have usually used resistance tests to see whether the drugs a patient is taking still work. Now doctors will have to use the relatively expensive tests in patients with new infections, Bozzette says.

The study, begun in 1996, collects blood samples from more than 1,600 U.S. men and women with HIV infection. Samples tested in 1999 showed that:

  • 70% of samples were resistant to one or more NRTIs, the oldest class of anti-HIV drug.
  • 42% of samples were resistant to one or more PIs.
  • 31% of samples were resistant to one or more NNRTIs.
  • Resistance was much more common among people whose treatment was failing (based on HIV disease stage and measures of immune function).
  • Resistance was more common in people with the best access to treatment: non-Hispanic white males, highly educated people, people with private insurance, and men who have sex with men.

Why so much resistance? It's partly due to how hard it is to take drugs every single day of one's life -- especially when they often have serious side effects. Another factor, Bozzette says, is that nobody knew the best way to use anti-HIV drugs when they first became available.

"Certainly one would have to ascribe some of this to patient compliance, and some to doctor's prescribing practices," Bozzette says. "What the best experts were doing in the early '90s turns out to have been exactly the wrong thing."

The good news is that HIV treatment is getting more sophisticated. New anti-HIV drugs -- and new classes of these drugs -- already are on the way. And now doctors have a much better idea of how to use them. That's a good thing, because many clinicians admit that only half of their patients get a true long-term benefit from anti-HIV treatment.

"Outcomes are steadily improving," Bozzette says. "I have sense that we are doing better than that now."

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