AIDS Behav

HIV diagnoses among men who have sex with men (MSM) have been increasing in several high-income countries. A better understanding of the sexual behavior trends among MSM can be useful for informing HIV prevention. We conducted a systematic review of studies that examined behavioral trends (1990-2013) in any condomless anal sex, condomless anal sex with an HIV-discordant partner, and number of partners. Studies included come from the United States, Europe, and Australia. We found increasing trends in condomless anal sex and condomless anal sex with an HIV-discordant partner, and a decreasing trend in number of partners. The increase in condomless anal sex may help to explain the increase in HIV infections. More explanatory research is needed to provide insight into factors that contribute to these behavior trends. Continuous monitoring of HIV, risk behaviors, and use of prevention and treatment is needed to evaluate prevention efforts and monitor HIV transmission risk.CC999999/Intramural CDC HHS/United States2018-10-01T00:00:00Z28555317PMC5708163vault:2528