Genetic Testing of HIV to Identify Resistance to Drug Treatment Found to be Cost-effective
For immediate release: March 19, 2001
Boston, MA--Despite significant gains in treating people with HIV, antiretroviral drug therapy initially fails in nearly half of those patients. A common reason is that the virus develops resistance to some of the drugs being used. Genetic testing to identify strains of the virus that are drug resistant can help clinicians adjust the "AIDS cocktail" mix of drugs so therapy is more effective.
A new study led by the Harvard Center for Risk Analysis, published this week in the Annals of Internal Medicine, (www.annals.org), finds that such resistance testing is a cost-effective use of resources in the battle against HIV. In fact, the study finds that investing in this genetic resistance testing is as approximately as cost-effective as the money spent on the drug therapy itself.
The study was led by Milton C. Weinstein, Ph.D., Sue Goldie, M.D., M.P.H., and Kenneth A. Freedberg, M.D., M.Sc., of the Program for the Economic Evaluation of Medical Technology, part of the Harvard Center for Risk Analysis. They found that when genotypic resistance testing is used for patients already on drug therapy – known as secondary testing - it extends life expectancy by three months at a cost of $17,900 per Quality Adjusted Life Year (QALY) gained. (A QALY is a metric for gains in longevity, adjusted to also account for the quality of that longer life.)
The study is also relevant to primary testing – the use of genotypic resistance testing before an HIV-positive patient begins drug therapy. Primary testing can determine whether the person has acquired a strain of HIV that is already resistant to some drugs. That allows clinicians to prescribe a combination of agents that have a greater likelihood of success. New evidence suggests a high and rapidly increasing prevalence of cases in which people first diagnosed with HIV are found to have acquired strains that are already drug resistant.
The study found that primary testing is also cost-effective, ranging between $22,300 and $69,000 per QALY gained, depending on variations in the prevalence of resistant strains of HIV in a given community. The more prevalent these strains are, the more likely they are the ones that will spread, and the more cost effective it is to do primary testing.
Genotypic resistance testing compares favorably against other common HIV treatments; $16,000 per QALY for prophylaxis against Pneumocystis carinii pneumonia, and $35,000 per QALY for prophylaxis using azithromycin against Mycobacterium avium.
The study, funded by the National Institute of Allergy and Infectious Diseases and the U.S. Centers for Disease Control and Prevention, should help clinicians and policy makers make more informed choices in allocating resources in HIV treatment. Specifically, it will help inform the current debate on the use of genotypic resistance testing. Three expert panels recently have advised its use, but several researchers question its cost-effectiveness.
The Harvard Center for Risk Analysis (HCRA) is part of The Harvard School of Public Health. HCRA is supported by funds from government, industry, and academia. Further information about the Center is available at www.hcra.harvard.edu.
For further information, please contact:
Harvard Center for Risk Analysis
Harvard School of Public Health
677 Huntington Avenue
Boston, MA 02115