STANFORD, Calif. - The key to combating AIDS in Russia may be to treat HIV-infected drug users. A new model estimating the spread of HIV in Russia suggests that treating injection drug users with antiretroviral medication will slow transmission of the virus among the general population.
The study, which will appear in the December issue of the journal AIDS, was led by Douglas Owens, MD, a researcher at the Veterans Affairs Palo Alto Health Care System and professor of medicine at the Stanford University School of Medicine, and Margaret Brandeau, PhD, professor of engineering at Stanford.
Estimates vary, but around 1 million Russians - slightly more than 1 percent of the adult population - are infected with HIV, the virus that causes AIDS. Injection drug users account for three-quarters of all HIV cases in Russia, and the epidemic is spreading rapidly to non-drug users. According to the United Nations, Russia's HIV infection rate is among the fastest-growing in the world. By 2020, HIV could afflict 14.5 million Russians, according to a study from the Woodrow Wilson Center in Washington, D.C.
Advances in antiretroviral therapies have the potential to stem the spread of the virus in Russia, but in 2005 less than 1 percent of HIV-infected Russians - 5,000 people - received the life-extending drugs.
The situation is worse among drug users. "Almost no injection drug users in Russia are getting antiretroviral drug therapy," said Owens.
Antiretroviral therapies now combine multiple individual drugs to reduce the amount of virus in a person's body. The cumulative effect of two or three medicines works better than a single one to keep the virus at bay. Antiretroviral therapies have the added benefit of reducing the chances that an infected person will transmit HIV to others.
To understand how antiretroviral therapy could affect HIV transmission in Russia, Owens and Brandeau, along with doctoral student Elisa Long, created a computer model of the virus' spread through the adult population in St. Petersburg, Russia. They accounted for infection rates among drug users and non-drug users and the reduced viral transmissibility and increased life expectancy of infected individuals on antiretroviral medication.
The researchers examined the hypothetical impact of treating only non-drug users, treating only addicts, treating both groups or maintaining the status quo. Owens called the approach a "thought experiment," designed to predict how treating different groups in the population would affect the overall epidemic.
"Exclusively treating non-drug users is not a wise approach. It's the least efficient and it's the least effective," said Long.
According to the model, treating only HIV-infected drug users will prevent more infections among non-drug users than exclusively targeting the non-drug users. Injection drug users are likely to spread HIV through unprotected sex, so reducing their ability to spread the virus can significantly reduce the spread of HIV to the general population.
The researchers also looked at the expense of the various treatment strategies, which had an estimated cost between $9.4 and $11.2 billion over 20 years. Giving medication only to non-drug users was not the most expensive approach, but it prevented the fewest new infections, according to the study. Treating both populations equally provided the most health benefit for the money, said Owens.
One key to implementing treatment programs will be keeping injection drug users on their HIV medications, said Owens. Antiretroviral therapy regimens have become much simpler, often requiring patients to take just one or two pills per day.
"If they can get the treatment and support, intravenous drug users can do well taking their medications," said Owens.
The study has important implications for Russia's approach to combating AIDS. Antiretroviral therapy is expanding in Russia, but it remains to be seen whether drug addicts will receive treatment, Owens said. "Our main message is that really to have an impact on the epidemic, you have to treat both the drug users and non-drug users."
Among the other co-authors were researchers from the Stanford Department of Engineering and Management Science and Stanford's Center for Primary Care and Outcomes Research. "What was really great about this project was that it was such an interdisciplinary effort," said Long, the study's first author. The research also was facilitated by Peter Hartsock, PhD, at the National Institute on Drug Abuse, who helped the Stanford team make contact with investigators and policy makers in Russia.
The National Institute on Drug Abuse and the Department of Veterans Affairs funded the study.
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