The role of risk reduction behaviours in HIV acquisition in gay men
Background: HIV risk reduction behaviours such as serosorting (SS) and strategic positioning (SP) are increasingly being reported in homosexual men, but whether they are effective in reducing HIV risk is uncertain.
Methods: Between 2001 and 2004, 1,427 initially HIV-negative men were enrolled in the Health in Men cohort. They were interviewed six-monthly through to June 2007 and tested annually for HIV. HIV risk reduction behaviours were defined behaviourally. SS was defined as reporting unprotected anal intercourse (UAI) with HIV negative partners only, regardless of regular or causal partners, and SP as reporting insertive UAI only in the six-month period between interviews.
Results: Among men reporting UAI, the proportion of men who practised SS increased from 48.2% in 2001 to 68.5% in 2007 (p<0.001). Compared with men who reported SS, men who reported UAI with HIV status unknown or HIV positive partners were at increased risk of infection (HR=2.05, 95% CI 0.96-4.37 and HR=7.41, 95% CI 3.48-15.77 respectively). Over time, about 25% men reported SP and this did not vary with time (p=0.513). Compared with men who reported SP, men who reported receptive UAI with withdrawal and with ejaculation were at significantly elevated risk (HR=3.25, 95% CI 1.03-10.20 and HR=3.02, 95% CI 1.05-8.68 respectively). Men who practised either SS or SP were less likely to adopt the other (OR=0.44, 95% CI 0.38-0.52). However, no men who reported both SP and SS seroconverted to HIV.
Conclusions: SS has been increasingly adopted by HIV-negative men. In this study, both SS and SP provided some protection against HIV infection. However, men who practised one HIV risk reduction behaviour were less likely to adopt the other. Whether these behaviours could result in a reduction in HIV incidence in gay men depends on the extent to which they replace higher risk forms of UAI.
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