How many guys are “sero-adapting” in San Francisco?
The researchers set out to define and measure the prevalence of HIV seroadaptive behaviors among men who have sex with men (MSM). Time-location sampling was used to recruit a community-based, cross-sectional sample of 1,211 HIV-negative and 251 HIV-positive MSM in San Francisco in 2004.
To define seroadaptive behaviors, all episodes of anal intercourse were enumerated and characterized by partner type, partner HIV serostatus, sexual position, and condom use for up to five partners in the preceding six months.
The results showed that 37.6 percent of HIV-negative MSM engaged in some form of seroadaptive behavior: pure serosorting (24.7 percent), seropositioning (5.9 percent), condom serosorting (3.9 percent), and negotiated safety (3.1 percent). Some form of seroadaptation was noted for 43.4 percent of HIV-positive men — including pure serosorting (19.5 percent), seropositioning (14.3 percent), and condom serosorting (9.6 percent). Consistent use of condoms was reported by 37.1 percent of HIV-negative men and 20.7 percent of HIV-positive men.
“In aggregate, seroadaptive behaviors appear to be the most common HIV prevention strategy adopted by MSM in San Francisco as of 2004,” the authors concluded. “Surveillance and epidemiological studies need to precisely measure seroadaptive behaviors in order to gauge and track the true level of HIV risk in populations. Rigorous prevention research is needed to assess the efficacy of seroadaptive behaviors on individuals’ risk and on the epidemic.”
Check out other LifeLube posts on this topic:
Interesting, this really represents a shift in how we think about prevention behavior among gay and bisexual men.
Serosorting May Increase the Risk of HIV Acquisition Among Men Who Have Sex With Men
Wilson, David P. PHD; Regan, David G. PHD; Heymer, Kelly-Jean BSc; Jin, Fengyi PHD; Prestage, Garrett P. PHD; Grulich, Andrew E. PHD
Background: Serosorting, the practice of seeking to engage in unprotected anal intercourse with partners of the same HIV status as oneself, has been increasing among men who have sex with men. However, the effectiveness of serosorting as a strategy to reduce HIV risk is unclear, especially since it depends on the frequency of HIV testing.
Methods: We estimated the relative risk of HIV acquisition associated with serosorting compared with not serosorting by using a mathematical model, informed by detailed behavioral data from a highly studied cohort of gay men.
Results: We demonstrate that serosorting is unlikely to be highly beneficial in many populations of men who have sex with men, especially where the prevalence of undiagnosed HIV infections is relatively high. We find that serosorting is only beneficial in reducing the relative risk of HIV transmission if the prevalence of undiagnosed HIV infections is less than ∼20% and ∼40%, in populations of high (70%) and low (20%) treatment rates, respectively, even though treatment reduces the absolute risk of HIV transmission. Serosorting can be expected to lead to increased risk of HIV acquisition in many settings. In settings with low HIV testing rates serosorting can more than double the risk of HIV acquisition.
Conclusions: Therefore caution should be taken before endorsing the practice of serosorting. It is very important to continue promotion of frequent HIV testing and condom use, particularly among people at high risk.