Both older and younger gay men having more unprotected sex in San Francisco

2 April 2003

Estimated reading time 3 minutes

Both older and younger gay men in San Francisco are having more unprotected anal sex, according to research conducted by the city’s STOP AIDS Project.

In recent years alarm has been expressed in some quarters that gay men are becoming more likely to have unprotected anal sex, the main risk activity for the sexual transmission of HIV. Evidence of increased rates of sexually transmitted infections and studies into gay men’s sexual behaviour have provided some support for this theory.

HIV prevention workers at the STOP AIDS Project in San Francisco investigated whether unprotected anal sex was occurring more frequently amongst younger gay men born after 1975, who had not seen at first hand the “full brutality of the epidemic” or older gay men, born before 1964, who were either “burnt out on 20 years of prevention messages” or “fatalistic” about the inevitability of becoming HIV-positive.

Glossary

risky behaviour

In HIV, refers to any behaviour or action that increases an individual’s probability of acquiring or transmitting HIV, such as having unprotected sex, having multiple partners or sharing drug injection equipment.

drug interaction

A risky combination of drugs, when drug A interferes with the functioning of drug B. Blood levels of the drug may be lowered or raised, potentially interfering with effectiveness or making side-effects worse. Also known as a drug-drug interaction.

sample

Studies aim to give information that will be applicable to a large group of people (e.g. adults with diagnosed HIV in the UK). Because it is impractical to conduct a study with such a large group, only a sub-group (a sample) takes part in a study. This isn’t a problem as long as the characteristics of the sample are similar to those of the wider group (e.g. in terms of age, gender, CD4 count and years since diagnosis).

confounding

Confounding exists if the true association between one factor (Factor A) and an outcome is obscured because there is a second factor (Factor B) which is associated with both Factor A and the outcome. Confounding is often a problem in observational studies when the characteristics of people in one group differ from the characteristics of people in another group. When confounding factors are known they can be measured and controlled for (see ‘multivariable analysis’), but some confounding factors are likely to be unknown or unmeasured. This can lead to biased results. Confounding is not usually a problem in randomised controlled trials.

unprotected anal intercourse (UAI)

In relation to sex, a term previously used to describe sex without condoms. However, we now know that protection from HIV can be achieved by taking PrEP or the HIV-positive partner having an undetectable viral load, without condoms being required. The term has fallen out of favour due to its ambiguity.

Accordingly, surveys of gay men’s sexual behaviour which the STOP AIDS Project conducted between 1994 and 2001 were examined. The one page survey recorded demographic information and questions about sexual risk over the previous six months including unprotected anal sex and number of partners. Men completing the survey were also asked to give details of their own and their partners’ HIV status. The survey was completed by 5,147 young gay men and 23,852 older gay men.

Four trends in HIV risk behaviour were tracked. Any unprotected anal sex; unprotected anal sex with two or more partners; unprotected anal sex with a partner of unknown HIV status; and unprotected anal sex with two or more partners of unknown HIV status.

All four trends in both younger and older gay men increased, with the number of younger and older gay men reporting each risk behaviour approximately doubling over the seven years of the studies.

Initial examination of the data suggested that unprotected anal intercourse increased more rapidly amongst younger gay men than amongst older gay men. However, analysis accounting for potential confounding factors, including interaction between the age of respondents and the year of the survey, found no evidence of a significant difference in rate of increase. “In other words, the data support increasing risk behaviour in both older and younger men who have sex weith men, not predominately in one or the other.” The investigators believe that their findings are reliable, pointing to the size of the study sample and the diverse range of venues used for the recruitment of participants.