Quarter of Swiss gay men using serosorting, strategic position or withdrawal to reduce their HIV risk

Michael Carter
Published: 16 June 2010

Almost two-thirds of gay and bisexual men consistently use condoms with casual partners as a means of HIV prevention, Swiss investigators report in the online edition of the Journal of Acquired Immune Deficiency Syndromes.

However, their research showed that 25% of men used strategies such as serosorting, strategic positioning, and withdrawal before ejaculation to try to reduce the risk of HIV transmission when having unprotected anal intercourse with casual partners.

“It is necessary to recognize the most commonly used risk reduction practices among men who have sex with men and address this practices in prevention activities in a balanced way,” write the investigators.

Gay men remain one of the groups most affected by HIV, and research from a number of industrialised countries has shown that the number of gay and other men who have sex with men reporting unprotected anal intercourse with casual partners has increased in recent years.

The same research suggests that although a significant proportion of men are not consistently using condoms, they are nevertheless using other methods to try to reduce the risk of HIV transmission.

These include serosorting – the conscious selection of partners who are believed to be of the same HIV status; strategic positioning – the adoption of the insertive or receptive position during anal intercourse according to HIV status; and withdrawal before ejaculation.

Such strategies do not have the same protective effect as consistent condom use, and Swiss investigators wished to establish their prevalence and the factors associated with them.

They therefore analysed the results of a nationwide sexual behaviour survey conducted in 2007.

A total of 2953 men completed the survey and 1689 (57%) reported anal sex with a casual partner in the previous twelve months. These men were included in the investigators' analysis.

Approximately three-quarters of these men were aware of their HIV status, and 145 reported that they were HIV-positive.

Overall, 67% of men said that they consistently used condoms with casual partners.

But consistent use of condoms was consistently lower amongst HIV-positive than HIV-negative men (47 vs 69%, p < 0.001).

Men with HIV were significantly more likely to sometimes employ a risk reduction strategy than HIV-negative men (35 vs 25%, p < 0.001).

Overall, 9% of men reported inconsistent condom use outside the context of risk reduction, those with HIV being the most likely to report this behaviour.

Withdrawal was the most widely used method of risk reduction (62%), followed by serosorting (50%), and strategic positioning (33%).

The investigators express “great concern” about the large number of men sometimes relying on withdrawal. Previous research found that this was associated with a high risk of becoming infected with HIV.

Factors associated with the use of risk reduction included being in a stable relationship, using the internet to find sex partners, age, and – for HIV-positive men – a higher number of sex partners (all p = 0.05).

No or inconsistent condom use was associated with sex seeking on the internet, age, and – for men with HIV – a greater number of partners (all p = 0.05).

“Risk reduction practices used with the intention to avoid HIV transmission were highly prevalent among men who have sex with men,” comment the investigators.

They add, “such practices were never promoted as such in Switzerland by either public health authorities or gay organisations; on the contrary, the prevention web site of the Swiss AIDS Foundation warns about their questionable efficacy.”

Further research is needed to understand the circumstances in which gay men use risk reduction, say the researchers. They also believe that prevention campaigns that address these strategies in a “balanced” way are needed.


Balthasar H et al. Intentional risk reduction practices of men in Switzerland who have anal intercourse with casual male partners. J Acquir Immune Defic Syndr, advance online publication, 2010.

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