27. CAN UNPROTECTED ANAL INTERCOURSE WITH REGULAR AND CASUAL PARTNERS EXPLAIN THE DIVERGING TRENDS IN HIV EPIDEMIC IN AUSTRALIA?

Introduction: Worldwide, increases in unprotected anal intercourse have been linked to the resurgence in HIV and STI in gay men. We assessed whether changes in UAI within regular and casual relationships may explain the diverging trends in HIV in three Australian states - NSW, Victoria and Queensland. Methods: We used the data from the annual cross-sectional Gay Community Periodic Surveys conducted annually in Sydney since 1996 and in Melbourne and Queensland since 1998. A short self-administered questionnaire asks about HIV serostatus, sexual health testing and behaviours relevant to HIV epidemic. We present time trends in seroconcordance and unprotected sex with regular and casual partners. Results: Currently, about one third of gay men report being in monogamous regular relationships, and this proportion has been slowly increasing everywhere. The self-reported UAI with regular partners (UAIR) was highest among men in seroconcordant positive relationships, lower among seroconcordant negative partners and lowest in non seroconcordant relationships. From 1998 to 2006, the rates of UAIR consistently increased by 10% in all three states and in all relationships by serostatus. The rates of UAI with casual partners (UAIC) were historically highest in NSW. From a peak in 2001, UAIC rates have consistently declined in NSW, but continuing increases were observed in Victoria and Queensland. Higher rates of nondisclosure of HIV were also observed in the context of UAIC in the latter two states. Conclusion: Changes in unprotected sex with casual partners may be responsible for the slowing of HIV epidemic in NSW. Sustained investment in policies and programs are important in achieving behaviour change.