UW News

July 22, 2004

National study finds limited benefit for behavioral intervention in HIV prevention

A national study has reinforced that behavioral interventions are effective in preventing the spread of human immunodeficiency virus (HIV) among men who have sex with men (MSM). These men accounted for 44 percent of all new HIV diagnoses in the United States in 2002. The results of the EXPLORE study, sponsored by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, were published last week in the medical journal, The Lancet. UW researchers conducted the Seattle part of the study.

The EXPLORE study is the largest of its kind to test a behavioral intervention as a possible means to prevent new HIV infections among the men, researchers say. NIAID funded the study of 4,295 uninfected men at high risk for HIV infection in six cities: Boston, Chicago, Denver, New York, San Francisco and Seattle. EXPLORE researchers found that the men engaged in this intensive behavioral intervention experienced an 18.2 percent reduction in HIV acquisition, compared with men receiving semi-annual voluntary HIV counseling and testing.

Researchers stress that this difference was not statistically significant and was not at the level of benefit targeted by the research team. However, men receiving the intervention reported a statistically significant 20.5 percent decrease in high-risk behavior over the course of the study.

“The lower numbers of new HIV infections in the intensive counseling group suggest a possible modest benefit over the standard counseling. It was rewarding and reinforcing to see a reduction in risky behavior among people in both groups, with a greater reduction in highest risk behaviors in the intervention group,” said UW principal investigator Dr. Connie Celum, a professor of medicine. “Seattle made a great contribution to this landmark behavioral study. We’d like to thank all of our participants for their time and commitment to this clinical trial. We hope that our further analyses of the data will help us develop even more effective behavioral interventions.”

The Seattle site enrolled 743 study participants and maintained a retention rate near 90 percent in both the intervention and control groups over the four-year study.

The intervention provided 10 intensive one-on-one counseling modules during the initial four to six months of the study, followed by maintenance sessions at three-month intervals throughout the four-and-a-half-year study. Participants in the control group received standard voluntary counseling and testing every six months.

Declines in sexual risk were seen in both arms of the study. The full effect of the intervention may have been harder to demonstrate, say the investigators, because participants in both arms received considerable attention over the course of the study to maintain involvement and retention. The HIV counseling and testing given to the control arm participants may have been more frequent and higher quality that is typically given in anonymous testing and counseling services. These study elements may have led all participants to lessen their behavioral risk, say the investigators.

The EXPLORE study received support from the HIV Prevention Trials Network and was sponsored by the National Institute of Allergy and Infectious Diseases. The National Institute of Child Health and Human Development, the National Institute on Alcohol Abuse and Alcoholism, the National Institute on Drug Abuse, the National Institute of Mental Health, and the Office of AIDS Research all provided funding for the study. It was conducted through contracts with Abt Associates Inc., Family Health International and the Fred Hutchinson Cancer Research Center, and subcontracts with the UW and other researchers nationwide.