Optimism about HIV doesn't explain why Scottish gay men having more risky sex

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Increases in the proportion of Scottish gay men reporting unprotected sex with casual partners cannot be explained by optimism about HIV, according to a study published in the March 25th edition of AIDS.

HIV optimism (the belief that HIV infection has become a less serious condition as a result of improved treatment) has been suggested as a possible reason for an apparent increase in the amount of unprotected anal intercourse with casual partners reported by gay men in studies in both the US and Europe. Although some studies have found a relationship with HIV optimism and risky behaviour, others have not (see links to two recent news stories reported on aidsmap below).

In 1999 and 2002 investigators questioned a cross-sectional sample of gay men in gay venues in Glasgow and Edinburgh. HIV optimism was assessed by looking at responses to two questions. The first of these questions asked if men were less worried about HIV since improved treatments became available, and the second asked men if they believed anti-HIV treatments made HIV-positive men less infectious.

Glossary

multivariate analysis

An extension of multivariable analysis that is used to model two or more outcomes at the same time.

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).

p-value

The result of a statistical test which tells us whether the results of a study are likely to be due to chance and would not be confirmed if the study was repeated. All p-values are between 0 and 1; the most reliable studies have p-values very close to 0. A p-value of 0.001 means that there is a 1 in 1000 probability that the results are due to chance and do not reflect a real difference. A p-value of 0.05 means there is a 1 in 20 probability that the results are due to chance. When a p-value is 0.05 or below, the result is considered to be ‘statistically significant’. Confidence intervals give similar information to p-values but are easier to interpret. 

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.

A total of 2,498 men participated in the survey in 1999 and 1,734 in 2002.

Men who said they “strongly agreed” with either of the statements were classified as optimistic, and men “strongly disagreeing” as not optimistic.

The investigators found that the proportion of men reporting unprotected anal sex with a casual partner increased from 10.5% in 1999 to 18% in 2002 (p<0.001).

There was also an increase in the proportion of men expressing optimism about HIV. In 1999, 13.9% of men strongly agreed that they were less worried about HIV because of new treatments. This increased to 23.2% in 2002 (p<0.001). Similarly, there was an increase in the number of men agreeing that new treatments made men with HIV less infectious. The proportion of men strongly agreeing with this increased from 7.6% in 1999 to 12.5% in 2002 (p<0.001).

Further, men providing optimistic responses to the two statements were more likely to reported unprotected sex with casual partners (19.6% versus 12.8%, p<0.001) question one, and 21.1% versus 13.2%, p<0.001, question two).

Unadjusted odds for unprotected sex with casual partners were higher in 2002 than 1999. In multivariate analysis, although both survey year and HIV optimism remained significant predictors for unprotected sex, there was no significant interaction between the two (p=0.7).

The investigators repeated their analysis separately for men who had tested for HIV and men who had not. The investigators found that only the survey year remained significant (p<0.001). Therefore, even though the percentage of never-tested men reporting unprotected sex increased between 1999 and 2002, the rate of increase was greater amongst men who were not optimistic.

The investigators comment that although men who were optimistic about HIV were more likely to report unprotected sex, both the year of survey and HIV optimism were “significantly and independently associated with sexual risk in multivariate analysis”. The investigators further explain, “If HIV optimism alone explained the increase in sexual risk, either the year of survey would not have remained significant or there would have been a significant interaction between year and optimism. In fact, the survey year remained significant after controlling for optimism.”

“Our results strongly suggest that HIV optimism cannot explain the recent increase in high-risk sexual behaviour among Scottish gay men,” conclude the investigators, who recommend that urgent attention be given to the identification of other factors associated with risky sex.

Further information on this website

Gay men realistic, not optimistic about HAART says study - news story

The dark side of HAART optimism? More unsafe sex and poor adherence - news story

References

Williamson LM et al. HIV optimism does not explain increases in high-risk sexual behaviour among gay men in Scotland. AIDS 18: 834-845, 2004.