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How Safe is HIV Serosorting for Men who have Sex with Men?

HIV “serosorting” -- in which HIV positive people have unprotected sex only with other positive people, and negative people only with other negatives -- has been proposed as a strategy for reducing the risk of HIV transmission. The method is far from foolproof, however, requiring that individuals accurately know and honestly convey their current status.

As reported in the October 2008 Journal of Acquired Immune Deficiency Syndromes, Matthew Golden and colleagues evaluated the epidemiology of serosorting among men who have sex with men (MSM).

Reports from San Francisco, London, and Sydney indicate that a growing number of men may be practicing serosorting, the authors noted as background, and some investigators have suggested that this might be preventing large increases in HIV infection rates even as rates of bacterial sexually transmitted diseases (STDs) among MSM have risen.

The present study included gay and bisexual men seen at an STD clinic in Seattle between 2001 and 2007. Data was collected at more than 10,000 visits. Participants were classified according to whether they reported non-concordant (with a partner of a different HIV status) unprotected anal intercourse, unprotected anal intercourse only with partners thought to be HIV negative, no unprotected anal intercourse, or no anal intercourse at all.

Results

• Men reported serosorting during 3295 of 12,449 visits (26%).
• From 2001 through 2007, the proportion of visits during which men reported serosorting increased (P = 0.02).
• This increase was greater among HIV positive compared with HIV negative men.
• Among men who tested HIV negative during the preceding year, the following percentages later tested positive:

o   49 of 1386 (3.5%) who reported non-concordant unprotected anal intercourse;

o   40 of 1526 (2.6%) who had sex only with presumed HIV negative partners;

o   28 of 1827 (1.5%) who had only protected anal intercourse;

o   0 of 410 who had no anal intercourse (P < 0.0001).

• 32% of new HIV infections occurred among HIV negative serosorters who assumed they were having unprotected sex only with HIV negative partners.
• The prevalence of HIV was higher among serosorters tested during 2004-2007 than among those tested during 2001-2003 (0.85% vs 3.2%; P = 0.03).

Based on these findings, the study authors wrote, “Serosorting offers MSM limited protection from HIV.”

In their discussion, they elaborated, “We found that our MSM patients acknowledged a behavior consistent with serosorting during more than a quarter of all clinical encounters; that the practice was increasing, particularly among HIV-infected MSM; that serosorting was associated with a lower risk of testing HIV positive than non-concordant unprotected anal intercourse, but a higher risk than universal condom use; that serosorting was associated with no decrease in the risk for bacterial STD; and that the protective efficacy of serosorting may be declining.”

Overall, they continued, “our findings support the conclusion that serosorting offers partial protection from HIV; it is better than having non-concordant unprotected anal intercourse, but not as good as universal condom use.”

However, they added, “from both a personal and a public health perspective, the limits of serosorting seem to be profound. The practice appeared to reduce the risk of acquiring HIV by < 50% compared with having sex with partners of unknown or discordant HIV status, and 32% of all MSM with newly diagnosed HIV reported that unprotected anal intercourse with a partner they believed to be HIV negative was their most risky sexual behavior. This finding suggests that the population-attributable risk associated with serosorting may be high.”

This study focused on serosorting by men who believed they were HIV negative and sought sex with other negative men. The authors acknowledged that serosorting “does not pose the same risk” for HIV positive serosorters, though they may still become infected with other STDs and may be at risk for HIV super-infection (though this appears to be rare).

“Whether trying to increase serosorting is a good idea depends on what behavior it replaces,” they concluded. “To the extent that men adopted it as an alternative to more consistent condom use, it is undesirable. Insofar as it replaces non-concordant unprotected anal intercourse, it should be encouraged. Clinicians and counselors should be able to discuss serosorting with their patients and clients, making clear that it is not an optimal strategy for avoiding HIV but that it may be a good step toward safety for some people.”

Beyond this, they added, “our findings highlight the need for HIV-uninfected men who serosort to test for HIV frequently using the most sensitive available tests (i.e., HIV RNA or HIV antigen tests) and to honestly discuss their HIV status and testing history with sex partners.”

Public Health, Seattle & King County, Seattle, WA; Center for AIDS and STD and Department of Biostatistics, University of Washington, Seattle, WA.

10/03/08

Reference

MR Golden, J Stekler, JP Hughes, and others. HIV serosorting in men who have sex with men: is it safe? Journal of Acquired Immune Deficiency Syndromes 49(2): 212-218. October 2008.