Hutch News

Prevention by intervention

Study uses HIV infection rates to measure effectiveness of behavioral intervention on AIDS transmission among men

July 15, 2004
Dr. Eugene Huang

Dr. Eugene Huang and colleagues found that intensive counseling provides some reduction in HIV transmission.

Photo by Todd McNaught

Intensive counseling on risky behavior may provide a modest reduction in HIV infection among men who have sex with men, according to a new study published in the July 3 issue of The Lancet. Among the study's more than 4,000 men in this high-risk group, those who were randomly assigned to a group that received 10 counseling sessions followed by quarterly maintenance sessions had a slightly more than 18 percent lower HIV-infection rate over a 54-month study period than those who were given two counseling sessions a year.

While this difference was not statistically significant in the screening trial, men in the more intensive counseling group did report a statistically significant 20.5 percent decrease in high-risk sexual behavior.

Men who have sex with men accounted for 44 percent of all new HIV and AIDS diagnoses in the United States in 2002. This study, known as EXPLORE, was the first to examine the effect of a behavioral intervention on AIDS-virus transmission among this population group using HIV infection as the measure of effectiveness. Previous studies have relied on self-reported risk behaviors to measure the impact of behavioral interventions, which is difficult to verify.

A feasible method

Although the researchers hoped to see a more substantial difference in HIV infection between the two groups in the study, the findings suggest that a behavioral intervention is a feasible method for reducing HIV infection rate and one that might be made more effective with further refinement.

The study involved participants in six U.S. cities and was conducted by the HIV Prevention Trials Network (HPTN), an international research effort focused on nonvaccine prevention strategies. The network's data operations center is housed within the Public Health Sciences Division's Statistical Center for HIV/AIDS Research and Prevention (SCHARP). Dr. Connie Celum, head of the Seattle HPTN site and an associate professor of allergy and infectious disease at the University of Washington, was one of the study's six site principal investigators. Dr. Eugene Huang, a SCHARP investigator, served as EXPLORE's lead statistician.

Despite the relatively modest reduction in infection rate among men in the intensive-counseling group, Huang said that much could be learned from the study to develop more effective ways to reduce HIV-infection rate.

"While we did see some benefit of this intervention, it isn't a home run," he said. "But because it was the first study of its kind to use HIV infection rather than self-reported behavior as the primary endpoint, it provides us with the most accurate picture to date about whether this type of behavioral intervention can work."

In addition, Huang said the study was notable for its high rate of participant retention and rate of adherence to the program. Both variables are crucial for accurately interpreting the outcomes of this kind of study. This study achieved a retention rate of 87 percent overall over a four-year period.

Participation parameters

EXPLORE involved 4,295 men ages 16 and older in Boston, Chicago, Denver, New York City, San Francisco and Seattle. Men were eligible for the study if they were negative for HIV antibodies and reported having intercourse with one or more men in the year before the study. After completing a baseline evaluation in which they received an HIV test and were questioned on demographics, attitudes toward safe sex and sexual behaviors, HIV-negative participants were randomly assigned to either an intervention group or a standard group.

Men in the intervention group received 10 individual one-hour counseling sessions within six months from the time they were assigned to the group. Sessions were designed to offer detailed personalized risk assessment and to address sexual communication, knowledge of self and partner's HIV-infection status in making sexual decisions, alcohol and drug use in conjunction with risk behaviors, and other information about safe sex. After the initial 10 counseling modules, maintenance sessions were delivered every three months through the end of the study. Of the 2,144 men assigned to the intervention group, nearly 75 percent completed all 10 initial sessions. Men assigned to the standard group received two risk-reduction counseling sessions during the course of a year.

Follow-up visits were scheduled for participants from both groups every six months, during which men completed surveys about their risk-associated behaviors and provided blood samples for HIV testing. Participants with positive HIV test results were referred for medical and social services.

At the end of the 54-month study, the researchers found that the HIV-infection rate was 18.2 percent lower in the intervention group than in the group that received standard counseling.

Huang said that further analysis of the EXPLORE data is now under way.

"This is a very rich data set, and many additional questions may be addressed. That would help develop more targeted and more effective behavioral intervention strategies," he said.

The HIV Prevention Trials Network

The HIV Prevention Trials Network (HPTN) is a worldwide, collaborative clinical trials network that develops and tests the safety and effectiveness of primarily nonvaccine interventions designed to prevent the transmission of HIV. Established in 1999 by the Division of AIDS (DAIDS) of the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH), the HPTN consists of more than two dozen international sites, including one at the University of Washington, and a leadership group comprised of three U.S.-based institutions. Fred Hutchinson's Statistical Center for HIV/AIDS Research and Prevention provides statistical and data management support for the network under the direction of Dr. Thomas Fleming of the Public Health Sciences Division.

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