AIDS Drugs Halve HIV Risk for IV Drug Users: Study

Public Health

Last Updated: 2013-06-12 17:00:25 -0400 (Reuters Health)

By Julie Steenhuysen

CHICAGO (Reuters) - A daily dose of antiretroviral medication helped cut the risk of HIV infection by 49% in intravenous drug users in a Bangkok study that showed for the first time that pre-exposure prophylaxis (PrEP) can work in this high-risk population.

"This is a significant step forward for HIV prevention," said Dr. Jonathan Mermin, director of the U.S. Centers for Disease Control and Prevention's Division of HIV/AIDS, which helped conduct the clinical trial along with the Thailand Ministry of Health.

The study was published today in the Lancet.  The drug used in the study was an older and relatively cheap generic HIV drug called tenofovir. The study was launched in 2005.

Prior studies of PrEP showed it cut infection rates by 44% in men who have sex with men, by 62% in heterosexual men and women and by 75% in couples in which one partner is infected with HIV and the other is not. The new results showed that it also protects intravenous drug users.

"We now know that PrEP can work for all populations at increased risk for HIV," Mermin said in a statement.

Based on the results, the CDC plans to recommend that U.S. doctors who wish to prescribe PrEP for their patients follow the same interim guidelines issued last year to prevent sexual transmission among other high-risk individuals.

Intravenous use of drugs like heroin accounts for about 8% of all new HIV infections in the United States and about 10% of new HIV infections worldwide. In some regions, such as Eastern Europe and Central Asia, injection drug abuse accounts for about 80% of all new infections.

The new findings involved more than 2,400 intravenous drug users in Bangkok who were not infected with HIV and were being treated at the city's drug treatment clinics.

Half took tenofovir and half took a placebo. All participants were given HIV prevention counseling, risk-reduction strategies such as condoms and methadone treatment, and monthly HIV testing.
At the end of the study, there were 17 HIV infections among people taking the HIV medication, compared with 33 infections among those not taking the drugs, the researchers found.

The researchers also looked to see what factors influenced infection rates among those taking the HIV medication. They found that people who took their medication at least 71% of the time had a 74% lower risk of becoming infected with HIV.

Although it was not clear how the preventive drug treatment worked - by stopping infections caused by sharing dirty needles or by unprotected sex among drug users - the study produced a reduction in infection rates, said Dr. Salim Abdook Karim of the University of KwaZulu-Natal in Durban, South Africa and of Columbia University in New York.

"The introduction of PrEP for HIV prevention in injecting drug users should be considered as an additional component to accompany other proven prevention strategies like needle exchange programs, methadone programs, promotion of safer sex and injecting practices, condoms, and HIV counseling and testing," Dr. Karim, who was not involved in the study, wrote in a commentary published with the study.

"PrEP as part of combination prevention in injecting drug users could make a useful contribution to the quest for an AIDS-free generation," Dr. Karim added.

SOURCE: http://bit.ly/7IymL

Lancet 2013.

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