Background:  Men who have sex with men (MSM) are the group most affected by HIV in the United States. However, the lifetime risk of acquiring HIV among MSM is not well defined, and the effect of HIV on the mortality of MSM in the birth cohort that reached adulthood during the HIV/AIDS epidemic is unknown.

Methods:  We used data from a 2003 telephone random digit dial survey of Seattle MSM and public health HIV/AIDS surveillance data to estimate the prevalence of HIV among MSM. We used HIV/AIDS surveillance data to calculate the number of MSM who had died with HIV in King County, Washington from 1983 to 2003, and US census data to define the size of the male population. We estimated the proportion of all men who were MSM using King County data from the 2003-2004 CDC Behavioral Risk Factor Surveillance System (BRFSS), as well as data from a national household probability study (National Health and Social Life Survey). We used 2003 US National Vital Statistics to define the overall mortality rate of US men.

Results:  Based on random digit dial and HIV/AIDS surveillance data, in 2003 the prevalence of HIV among MSM living in King County at ages 18-30, 30-39, 40-49, and 50-59 were 3%, 13-17%, 21-22%, 15-19%, respectively. An estimated 6% of all men in King County were MSM. After adding MSM mortality data, in 2003 the percentage of MSM ages 18-30, 30-39, 40-49, and 50-59 who had been infected with HIV or who had died with HIV/AIDS were 3%, 16-20%, 35-36%, and 30-34%, respectively, for estimates based on the random digit dial and HARS data. By 2003, 3074 (53%) of the estimated 5005 King County MSM infected with HIV born between 1943 and 1963 had died.  These deaths represent an estimated 18% of all MSM in the 1943-1963 birth cohort. If the 5005 HIV-infected MSM had experienced a mortality rate similar to that of all US men of the same age, 189 (4%) would have died.

Conclusions:  HIV prevalence estimates among MSM based on random digit dial and HIV/AIDS surveillance data are very similar. Among King County MSM born between 1943 and 1963, approximate one-third have been infected with HIV.  In 2003, 15 to 19% of these men were living with HIV, and 18% had already died.