Which gay men should be the target for prevention work?

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Researchers at the International AIDS Conference in Mexico City have suggested a range of approaches for better defining the characteristics of gay men who are at greatest risk of being involved in HIV exposure or transmission, and who can be targeted for HIV prevention interventions.

Tania Gibbie used data on the factors that are associated with sexual risk-taking to develop an easy-to-use screening tool that could be used in primary care settings. The study is probably less interesting for its findings (which are based on a small sample) than for the way the data is being translated into a practical tool that can help healthcare staff identify men who may need support with HIV prevention.

The study was based on a sample of 152 gay or bisexual men in an Australian primary care setting (35% of whom were HIV-positive). Having found that in multivariate analysis a number of factors were associated with unprotected anal intercourse with casual or serodiscordant partners or with a recent sexually transmitted infection, a questionnaire was developed to identify men with those characteristics.


multivariate analysis

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


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).

safer sex

Sex in which the risk of HIV and STI transmission is reduced or is minimal. Describing this as ‘safer’ rather than ‘safe’ sex reflects the fact that some safer sex practices do not completely eliminate transmission risks. In the past, ‘safer sex’ primarily referred to the use of condoms during penetrative sex, as well as being sexual in non-penetrative ways. Modern definitions should also include the use of PrEP and the HIV-positive partner having an undetectable viral load. However, some people do continue to use the term as a synonym for condom use.


In discussions of consent for medical treatment, the ability of a person to make a decision for themselves and understand its implications. Young children, people who are unconscious and some people with mental health problems may lack capacity. In the context of health services, the staff and resources that are available for patient care.


A serodiscordant couple is one in which one partner has HIV and the other has not. Many people dislike this word as it implies disagreement or conflict. Alternative terms include mixed status, magnetic or serodifferent.

The questionnaire is as follows (multiple choice answers and scoring system not included).

  • How many casual partners have you had anal sex with in the past three months?
  • In the past three months, how often have you used the following skills to increase your safety during sex? Skills: The capacity to assert yourself; negotiate safe sex; say ‘no’ under pressure; knowledge of safe sex practices. (Men answering ‘sometimes’ or ‘never’ seen as riskier).
  • Do you believe anti-retroviral therapy (HIV treatment) has reduced your risk of catching or transmitting HIV?
  • Please indicate the extent you agree with the following statement: “I enjoy the sensation of intercourse without a condom”
  • In the past six months, have you used marijuana?

The questionnaire will now be validated with larger groups of men. However many previous studies in a number of settings have already generated large amounts of data on the factors associated with sexual risk-taking, raising the possibility that existing data sets could be used to develop similar diagnostic tools.

Another study was most interesting for the way it used emerging definitions of infectiousness (broadly in line with the Swiss statement) as part of its assessment of men who took sexual risks. Kenneth Mayer combined biological and behavioural characteristics in order to define what he called “high risk transmitters”. They are HIV-positive men who either:

  • Have a viral load above 75 copies/ml AND have had unprotected anal sex with a sexual partner of unknown or negative HIV status in the past six months, or
  • Have had gonorrhoea, syphilis or chlamydia in the last year AND have had unprotected anal sex with a sexual partner of unknown or negative HIV status in the past six months.

Mayer’s study was conducted with 201 gay and bisexual HIV-positive men attending Fenway Community Health in Boston. In this group 45% were classified as “high risk transmitters”.

Multivariate analysis was used to identify the factors associated with belonging to this group. Several risk factors related to substance use: more than five alcoholic drinks a day, any drug use, and crystal meth use. Moreover, while being diagnosed with HIV for less than nine years was associated with being a “high risk transmitter”, younger age was not. It was suggested that this may be due to being in contact with HIV care services for longer, or with a HAART era generational shift.


Gibbie T High risk sexual behaviour in men who have sex with men: the development of a sexual risk behaviour screening tool. XVII International AIDS Conference, Mexico City, abstract MOAC0101, August 4 2008.

Mayer K Which HIV-infected men who have sex with men (MSM) in care are most likely to transmit HIV to others? XVII International AIDS Conference, Mexico City, abstract THPDC201, August 7 2008.