New Cases of HIV Drug Resistance Dramatically Decreasing in British Columbia

Vancouver, January 7, 2010 — Fewer and fewer British Columbians are developing resistance to antiretroviral drugs used to treat HIV infection, according to a new study published this week in the journal Clinical Infectious Diseases.
The study, conducted by researchers at the British Columbia Centre for Excellence in HIV/AIDS (BC-CfE), found a significant decrease in the number of new cases of drug resistance over the past decade, alongside an increase in the number of patients successfully suppressing HIV to undetectable levels.  Together, these findings show that HIV treatment is becoming more effective and more robust, with a corresponding improvement in clinical outcomes for patients.

“These study results are good news for all HIV-positive British Columbians receiving therapy,” said Richard Harrigan, Ph.D., lead investigator and Director of Research Laboratories at the BC-CfE.

Dr. Julio Montaner, Director of the BC-CfE and President of the International AIDS Society, stated: “This is a real life example that shows current HIV management strategies, supported by the BC government, are working.  We can look forward to even better outcomes as the STOP HIV/AIDS initiative is rolled out in BC in the months to come.”

HIV drug resistance develops due to the virus’ ability to mutate rapidly under the selective pressure of antiretroviral therapy.  Since the introduction of the first generation of antiretrovirals in the mid 1980s, drug resistance has presented a significant obstacle to the effectiveness of HIV treatment and is a frequent contributing factor to the failure of drug regimens.

Using data drawn from all patients receiving treatment for HIV infection in British Columbia, the researchers found a 12-fold decrease in the number of new instances of HIV drug resistance between 1997 and 2008.  In 1997, the incidence rate of HIV drug resistance in British Columbia was 1.73 cases per person-month of exposure to therapy.  By 2008, the rate had fallen to 0.14 cases per person-month, having declined exponentially over the past decade with a half-time of 3.2 years.  Significantly, this reduction occurred despite a steady increase in the number of patient-months of exposure to therapy and increased cumulative exposure.

This study represents one of the first attempts to characterize the incidence of HIV drug resistance (number of new cases in a given period) as opposed to the prevalence (total number of cases).  While prevalence is a helpful gauge of the current burden of HIV drug resistance on a population, incidence is a valuable tool for describing the potential future burden.  The data suggest HIV drug resistance is becoming less of a challenge to therapy in resource-rich settings where Highly Active Antiretroviral Therapy (HAART) is freely available.  If current trends hold, HIV drug resistance could become a rare event in British Columbia.

About the B.C. Centre for Excellence in HIV/AIDS:
The BC Centre for Excellence in HIV/AIDS (BC-CfE) is Canada’s largest HIV/AIDS research, treatment and education facility. The BC-CfE is a program  at St Paul’s Hospital, Providence Health Care,  a teaching hospital of the University of British Columbia. Located in Vancouver, Canada, the BC-CfE is dedicated to improving the health of British Columbians with HIV through the development, monitoring and dissemination of comprehensive research and treatment programs for HIV and related diseases.