Posted by NewsFlash on December 19, 2001 at 17:58:48:
CHICAGO (Reuters Health) - Nearly 80% of HIV (news - web sites)-infected adults in the US harbor a viral strain that is resistant to one or more drugs used to fight the infection, according to a study presented here Tuesday.
``This is sobering but important information,'' said study leader Dr. Douglas Richman, of the Department of Veterans Affairs (news - web sites)' San Diego Health Care System. ``Both health care providers and patients need to use the drugs we have as intelligently as possible.'' The findings were presented to delegates attending the 41st Annual Interscience Conference on Antimicrobial Agents and Chemotherapy.
The study, the first to provide a national overview of drug resistance among HIV patients, also found that people being treated at larger centers were less likely to be drug resistant than those treated elsewhere.
``The more expert and experienced providers have better outcomes,'' Richman said. ``The use of antiretroviral drugs is a very complex specialty, it's as least as complex as oncology.''
In the study, Dr. N. Hellmann, from ViroLogic, Inc. in San Francisco, Richman and colleagues, tested 1647 blood samples obtained in early 1999 as part of the HIV Cost and Service Utilization Study.
Seventy-eight percent of HIV-infected adults harbored a drug-resistant virus, the investigators said. The highest resistance rate at 70% was seen for nucleoside reverse transcriptase inhibitors (NRTI), the class of drug that includes AZT. The resistance rates for non-NRTIs and protease inhibitors were 31% and 42%, respectively.
Patients currently taking antiretrovirals were more likely to demonstrate resistant HIV than patients not taking these drugs. However, resistant strains were still identified in 41% of patients not taking antiretroviral therapy. Greater access to treatment was directly linked to the prevalence of drug resistance.
``Initially, we expected to see some resistance but not a great deal,'' Hellmann told Reuters Health. ``We were surprised that more than three-quarters of patients had a virus that was resistant to at least one antiretroviral agent,'' he added. ''Everyone knows that HIV can mutate and develop resistance, but we never expected the rates to be this high.''
Hellmann noted that ``if you extrapolate the current findings to the entire study population, a conservative estimate would be that half have drug-resistant'' virus.
``The current findings are sobering,'' Hellmann said. In addition, ``the findings highlight the importance of resistance testing,'' he added. ``A lot has been done to control the morbidity and mortality of HIV infection, but, as our results emphasize, there is still no magic bullet.''
However, Richman noted that the study did reveal some good news. The proportion of HIV patients whose disease is suppressed and who don't have resistance is increasing. He said this is because patients were given so many types of drugs in the 1990s that ``people were accumulating drug resistance.'' Also, he said, today's drugs are more powerful.