Wednesday 25 July 2012

24 July: Tuesday (Post) Exposure

Edwina Wright and Dean Murphy
For me, Tuesday was particularly exciting because there were many sessions on HIV pre-exposure prophylaxis. In anticipation of this I breakfasted with Edwina Wright, ASHM president, with whom I had been working to develop a proposal to study how PrEP might be implemented in Australia.

A new terminology has entered PrEP discourse, which relates to 'seasonal' use. Seasonal use refers to using PrEP for limited periods—months or weeks—at times of greatest risk or need. Such sporadic use raises concerns about drug resistance and onward transmission of drug resistance. So there is a need for PrEP users to be aware of the symptoms of HIV seroconversion.

A popular session in which many people, including yours truly, were locked out due to overcapacity included discussion of demonstration projects, of which there are a number planned for gay men in the United States. The objectives are to measure uptake, adherence, persistence (i.e. 'staying on') side effects and toxicity, and changes in sexual behaviour.

In a lunchtime poster session there was further discussion about PrEP. Metsch presented findings on willingness to take PrEP among men in Miami and here in Washington DC. Duffus also presented findings from a study of PrEP attitudes among HIV-negative partners in serodiscordant relationships. In this study, there was high acceptability and interest in PrEP (94% of participants) but also there was noted the potential for 'behavioural disinhibition' with 27% noting that they would find it difficult to use condoms if taking PrEP. Greater knowledge about PrEP was also associated with increased PrEP acceptability. The issue of 'disinhibition' is worth further exploration now that there is efficacy data on PrEp demonstrating that if people take it fairly consistently then they are almost completely protected against HIV acquisition. 'Disinhibition' and 'risk compensation' may well have passed their use-by date.

Linda-Gail Bekker from South Africa presented findings from focus groups in South Africa including both men and women. In relation to intermittent and event-based PrEP dosing, Bekker's study found that 51% of participants could 'forecast' sex. With men being more likely to predict sex (75%) than women (32%). Modesty forbids me from describing my own poster today in too much detail. Suffice to say, it was also about sex planning. Based on a study of men in Australia we found that only a minority of anal sex among HIV-negative gay men in the previous week was planned (i.e. 'forecasted'). This suggests that if event-based PrEP using a dosing strategy of 24 hours in advance is, on its own, not likely to be successful and that some kind of intermittent plus event-based dosing is probably going to be more realistic.

Alex Caballo-Dieguez presented results of a bold study in New York about sexual partners and a home-based HIV test to screen sexual partners. The 27 men in the study were given home test kits and they asked 124 sexual partners to use the test. Of these 101 men agreed and 23 refused. Resistance from partners to testing was used as a reason not having unprotected sex, and led to two partner disclosing HIV-positive status. Mutual testing by participants and partners was frequent. There was a total of 10 positive HIV results.

Another session on PrEP examined PrEP-related attitudes. Based on a survey of 5,035 men in the US and Canada, Krakower presented findings that showed 19% had heard of PrEP although prior use was less than 1%. Half of all men would use PrEP (based on a single-item) and 20% would decrease condom use for insertive sex and 14% would decrease condom use for receptive anal sex. Martin Holt presented findings on attidues from the PrEPARE Project showing that there were overwhelmingly positive attitudes to PrEP among gay men in Australia, although much greater scepticism among the same men—and in particular the HIV-negative respondents—about ARV therapy reducing the risk of HIV transmission.

See also

Studies highlight complex questions about how communities will respond to PrEP Comment from AIDS map.

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