Drinking alcohol before sex increases risk of HIV infection

Drinking alcohol before sex is associated with an increased risk of acquiring HIV, a greater number of sexual partners, and inconsistent condom use, according to a large study conducted in Uganda and published in the May edition of AIDS. The American and Ugandan authors of the study note that in many resource-limited and middle-income countries the rates of alcohol consumption are high and HIV epidemics are worsening. They suggest that interventions to reduce alcohol consumption combined with HIV prevention work may help reduce the number of new HIV infections.

Alcohol is a very widely used drug that is enjoyed safely by millions of people worldwide. For many people, however, alcohol consumption is a serious health concern. One aspect of this is its ability to lower inhibitions, possibly resulting in sexual risk-taking. Investigators from the Rakai cohort study undetook a prospective study to determine if the consumption of alcohol before sex was associated with an increased risk of HIV acquisition and sexual risk behaviours.

The study ran between 1994 and 2002 and involved approximately 6,800 men and a little over 8,000 women. All were aged between 15 and 49 years and were followed up at intervals of roughly twelve months when they were tested for HIV. Data were gathered on sociodemographic characteristics, sexual risk behaviour and alcohol consumption in the past week in before sex.

During the course of the study, 287 men were infected with HIV, which is equivalent to 1.4 new infections per 100 person-years. In addition, a total of 384 women were also infected with HIV during the observation period, providing an incidence of 1.5 new infections per 100 person-years.

HIV incidence was, however, lower amongst men (0.9 per 100 person-years) and women (1.0 per 100 person-years) who did not drink alcohol. Alcohol consumption before sex by one partner increased HIV incidence to 1.7 per 100 person-years amongst men and 1.5 per 100 person-years amongst women. If both partners drank alcohol before sex then the incidence was increased even further to 1.8 per 100 person-years for men and 1.9 per 100 person-years for women.

When the investigators adjusted their results for sociodemographic factors and risk behaviours, alcohol consumption before sex was shown to increase the risk of acquiring HIV infection by 67% for men and 40% for women. If both partners used alcohol before sex then the risk increased by 58% for men and 81% for women.

The investigators also found an association between alcohol use before sex and HIV risk behaviours, with individuals consuming alcohol 38% more likely to report inconsistent condom use before sex, and 42% more likely to report a greater number of sexual partners. Married men and women were approximately 33% more likely to report extra-marital sex if they used alcohol first.

“Alcohol use...was associated with an increased risk of HIV acquisition in both sexes”, comment the investigators. They offer two possible explanations for this finding. First, “alcohol may affect HIV risk by behavioural disinhibition.” However, they also offer a second possible explanation, noting “it is possible that alcohol may affect HIV risk by impaired immune system regulation as suggested by in-vitro and simian studies.”

Problematic alcohol use can have implications both for the individual and for society, and the investigators conclude, “in many developing countries, and in the countries of the former Soviet Union and eastern Europe, alcohol use is common and HIV incidence rates are high or increasing. Therefore, designing and providing interventions to identify those at risk and to promote the reduction of alcohol use in conjunction with sex may provide a means of HIV prevention.”