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This section is devoted to the primary care of cisgender gay, bisexual, and other men who have sex with men (MSM) regardless of their sexual identity. Most health-related research that focuses on MSM categorizes men based on their sexual behavior as MSM, rather than their self-reported identification as gay, bisexual, or other identities. Although sexual identity is not always congruent with sexual behavior, identity is important to recognize to optimize health and health care, especially when there is a difference on the basis of sexual identity (for example, gay- versus bisexual-identified men).


The size of the MSM population in the United States is not known with certainty due to variability in the definition of sexual orientation used in surveys and the possibility that some survey respondents do not disclose gay or bisexual orientations because of concerns about discrimination. Nevertheless, based on available data, it is estimated that at least 2.2% of American adult men identify as gay, and an additional 1.4% of men identify as bisexual. The proportion of men who engage in sex with other men or experience sexual attraction to other men is estimated to be higher, with 7.3% and 6.2% of adult men reporting some same-sex attraction and sexual behavior, respectively, in one national survey.


Gay, bisexual, and other MSM face health disparities stemming from the biologic aspects of their sexual behavior or from minority stress, or both. Because of these disparities, MSM have been identified as a priority population for health-related research and improvement in health care by both the National Academy of Medicine and the federal government’s Healthy People 2020 initiative. These health disparities are exacerbated if MSM have experienced early life traumatic events, such as sexual abuse or familial rejection.

Institute of Medicine (US) Committee on Lesbian, Gay, Bisexual, and Transgender Health Issues and Research Gaps and Opportunities. The health of lesbian, gay, bisexual, and transgender people: building a foundation for better understanding. Washington, DC: National Academies Press (US); 2011.
[PubMed: 22013611]
Makadon  HJ, Mayer  KH  et al. The Fenway Guide to Lesbian, Gay, Bisexual, and Transgender Health, 2nd ed. American College of Physicians Press, 2015.
Office of Disease Prevention and Health Promotion (ODPHP). Healthy People 2020: lesbian, gay, bisexual, and transgender health. 2016.

A. HIV and Other STIs

MSM account for approximately 70% of all new HIV infections in the United States, despite representing a small proportion (less than 10% by any metric) of the country’s male population. The high burden of HIV infection among MSM stems in part from the efficient transmission of the virus through receptive anal intercourse, which confers a higher risk of HIV infection than other sexual activities, such as penile-vaginal and oral intercourse. Role versatility can also uniquely potentiate HIV spread among MSM, since the same person ...

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