A surprising 14 percent of new U.S. cases of HIV infection are already resistant to drugs that treat the virus, doctors said on Wednesday - meaning everyone newly diagnosed with HIV needs to find out which drugs are doomed to fail from the outset.
And at least 10 percent of people newly infected in Europe have a drug-resistant form of the virus, as well, researchers told a scientific meeting on AIDS, referring to an average of two studies in France and Switzerland.
This is grim news for patients, they said, who will have fewer drugs they can choose from to treat their illness.
"For recently infected people, clearly I think resistance testing is merited," Dr. Susan Little of the University of California San Diego, who led one of the studies, said in a telephone interview.
Doctors have debated whether the tests are worthwhile. But Little said her findings show many people are getting infected with a form of the virus that has already mutated so that it resists the effects of some of the 15 HIV drugs being used to treat the infection.
That means the odds are stacked against patients before they start any treatment.
Little and colleagues across the United States looked at blood tests from 394 patients in eight cities, none of whom had been given any HIV drugs at the time of the tests.
They used an assay made by ViroLogic, based in South San Francisco that tests the virus against the various HIV drugs.
Fourteen percent of all the patients had resistance to at least one HIV drug, Little told the Eighth Annual Retrovirus Conference being held in Chicago.
They compared people who became infected between 1995 and 1998, to those infected in 1999 and 2000. They saw a huge leap in the number of people who got a drug-resistant form of the virus to start with.
"The number went from 3.5 percent in 1995 to 1998, to 14 percent in 1999 to 2000," Little said.
MULTI-DRUG RESISTANCE RISES, TOO
When they looked for multi-drug resistance - resistance to two or more classes of drug at the same time - the numbers went from 0.4 percent of patients infected in 1995 through 1998 to 5.8 percent of those infected in 1999 and 2000.
"East coast, West Coast, Midwest - there was hardly any geographic variability," Little said.
Little's team tested the blood of patients long after they had been diagnosed, but taken at the time of initial diagnosis, so they were able to then check and see what happened.
As would be expected, these patients did not do as well when they took drug cocktails.
"They take longer to achieve virologic suppression, and fewer of them do achieve virologic suppression," Little said.
"Those who do suppress are more likely to fail their first regimen. They don't do as well with therapy."
Little believes that if every HIV patient were tested for drug resistance as soon as they were diagnosed doctors could better decide which drugs to give them and which drugs would be a waste of time.
Another team at Basel University Hospital in Switzerland and the Swiss Institute of Bioinformatics tested 197 people with HIV between 1996 and 1999. They found in 1996, 8.6 percent of those tested were infected with a virus that resisted at least one drug. The numbers rose to 14.6 percent in 1997 but fell to 5 percent in 1999.
A French team at Hospital Necker in Paris and the French research agency INSERM tested 108 HIV patients and found 10 percent had viruses that had evolved resistance against at least one drug.