Prevalence of HIV drug resistance high in the U.S. population
Source : AIDS 2004;18:1393-1401.
Last Updated: 2004-07-26

NEW YORK (Reuters Health) – On a U.S. population-basis, the prevalence of antiretroviral drug resistance is high, especially among HIV-infected adults treated early in the era of highly active antiretroviral therapy (HAART) but continue to have HIV plasma levels >500 copies/mL

Writing in the July 2nd issue of AIDS, Dr. Douglas D. Richman from the University of California San Diego and colleagues note that the prevalence of antiretroviral resistance has only been reported in select cohorts of "limited size and geographic representation. The true prevalence of HIV drug resistance has not been described in any large population."

The investigators report results of HIV drug susceptibility assays performed on 1099 plasma virus samples representing 132,500 HIV-infected Americans treated in early 1996 – the start of the HAART era. Despite therapy, these patients remained viremic in late 1998 with >500 copies/mL of HIV RNA.

They detected resistance to one or more HIV antiretroviral drugs in specimens representing roughly 101,100, or 76.3%, of the 132,500 viremic patients.

Among this group of patients, "the estimated prevalence of resistance to one or more drugs within each of the three drug classes ranged from 71.4% for nucleoside reverse transcriptase inhibitors to 40.5% for protease inhibitors and 25.2% for non-nucleoside reverse transcriptase inhibitors," they report.

About 13% of samples from viremic patients were resistant to all three drug classes.

HIV drug resistance was significantly more common in patients with advanced HIV disease, higher plasma viral loads, and lower CD4 cell counts as well as in "early adopters" of HAART or early users of nucleoside analogs.

"These first estimates of the prevalence of HIV drug resistance in adults across the United States have several clinical and public health implications, mostly deriving from the fact that suppression of circulating HIV is an important goal for improving patient outcomes and reducing transmission," the authors write.

"Clinicians and policymakers," they note, "need to be aware that this large population of patients with viral loads above 500 copies/ml while on therapy are likely to have more limited treatment options and a diminished probability of complete suppression of viral replication as a treatment outcome."

"This is the first and I believe only truly representative sample assessing HIV drug resistance in a large population," Dr. Richman told Reuters Health. "All studies have been convenience sample that only give indications of a true prevalence."

"This high rate of drug resistance in the population of patients under care has important consequences both for patient management and for transmission of drug resistant virus," he added.