Available evidence does not support serosorting as an HIV risk reduction strategy

Serosorting is an increasingly common practice among gay men whereby the selection of sexual partners is based on concordance of HIV serostatus [1-3]. Serosorting occurs in order to facilitate unprotected anal intercourse without risk of HIV transmission. Evidence suggests that disclosure of HIV serostatus is increasingly influential not only on the formation of casual partnerships among gay men (serosorting), but also on the sexual position that each man is likely to take in a coital act (known as strategic positioning) and the likelihood of using a condom (known as negotiated safety) [3-9]. Although these interrelated strategies appear to be sophisticated measures for reducing risk, in some circumstances they may lead to an increased risk of HIV transmission in a population [10,11]. Serosorting, when coupled with actual positioning and condom behavior, may result in an increased risk of HIV acquisition if a moderate proportion of the HIV-infected population is undiagnosed. This undiagnosed proportion may lead to the formation of partnerships that are thought to be concordant but are actually discordant. In partnerships that are thought to be concordant, HIV-negative men are more likely to take a receptive role (which is more risky in a discordant partnership) and less likely to use condoms.