High-risk sexual activity plays key role

HIV risk factors among injection drug users (IDUs) differ markedly by gender, according to a 10-year study funded by the National Institute on Drug Abuse (NIDA). A recent study by researchers at the Johns Hopkins University reported that while drug-related risk behaviors and homosexual activity are the most important predictors of HIV seroconversion among males, factors consistent with high- risk heterosexual activities are the main predictors among females. The findings, reported in the May 28 issue of the "Archives of Internal Medicine", provide insight into the relationship between gender and high-risk sexual behaviors in the development of HIV infection.

"Early studies of injection drug users suggested that most HIV infections were due primarily to sharing needles," said NIDA Director Alan I. Leshner, Ph.D. "This study adds to the body of evidence that supports the need for gender- specific interventions in the treatment of that group of drug users."

Between 1988 and 1998, a team of researchers, led by Dr. Steffanie Strathdee at the Johns Hopkins University Bloomberg School of Public Health, examined both drug related and sexual risk factors for HIV transmission in a study of more than 1,800 injecting drug users in Baltimore, Maryland. Study participants were aged 18 or older, did not have an AIDS defining illness at enrollment, and reported a history of illicit injection drug use within the previous 10 years. Through semi-annual interviews, researchers collected data on drug use history, sociodemographics, and drug use and sexual behavior within the last 6 months. Blood samples were also obtained at each study visit. Researchers used commercial HIV and antibody ELISA to identify those participants who had become HIV positive since their last visit.

Dr. Strathdee and her colleagues found that the greatest predictor for HIV seroconversion among both male and female IDUs was high-risk sexual behavior. Study findings revealed that male injection drug users who reported recent homosexual activity were four times more likely to become infected with HIV.

Among females, indicators of high-risk heterosexual activity outweighed needle-sharing behaviors as independent predictors of HIV seroconversion. HIV incidence was more than two times higher among women who reported recently having sex with another injection drug user.

Another common predictor of HIV seroconversion observed by researchers among both male and female IDUs was younger age. Investigators found that IDUs who were aged 30 or younger at enrollment were more than twice as likely to seroconvert than those aged 40 or older. "This is consistent with several reports which indicate that younger IDUs are more likely to engage in needle sharing and other behaviors that place them at higher risk of acquiring HIV and hepatitis B or C viruses," stated Dr. Strathdee.