Trends in serosorting and the association with HIV/STI risk over time among men who have sex with men (MSM).

Publication Type:

Journal Article


Journal of acquired immune deficiency syndromes (1999), Volume 72, Issue 2, p.189-197 (2016)


BACKGROUND: Serosorting among men who have sex with men (MSM) is common but recent data to describe trends in serosorting are limited. How serosorting affects population-level trends in HIV and other sexually transmitted infection (STI) risk is largely unknown. METHODS: We collected data as part of routine care from MSM attending an STD clinic (2002-2013) and a community-based HIV/STD testing center (2004-2013) in Seattle, Washington. MSM were asked about condom use with HIV-positive, HIV-negative and unknown-status partners in the prior 12 months. We classified behaviors into four mutually exclusive categories: no anal intercourse (AI); consistent condom use (always used condoms for AI); serosorting (condomless anal intercourse [CAI] only with HIV-concordant partners); and non-concordant CAI (CAI with HIV-discordant/unknown-status partners; NCCAI). RESULTS: Behavioral data were complete for 49,912 clinic visits. Serosorting increased significantly among both HIV-positive and HIV-negative men over the study period. This increase in serosorting was concurrent with a decrease in NCCAI among HIV-negative MSM, but a decrease in consistent condom use among HIV-positive MSM. Adjusting for time since last negative HIV test, the risk of testing HIV positive during the study period decreased among MSM who reported NCCAI (7.1% to 2.8%; P=0.02), serosorting (2.4% to 1.3%; P=0.17) and no CAI (1.5% to 0.7%; P=0.01). Serosorting was associated with a 47% lower risk of testing HIV positive compared to NCCAI (adjusted prevalence ratio=0.53; 95% CI=0.45-0.62). CONCLUSIONS: Between 2002 and 2013, serosorting increased and NCCAI decreased among Seattle MSM. These changes paralleled a decline in HIV test positivity among MSM.