Numbers of Men Who Have Sex With Men and Use Injection Drugs
Numbers of Men Who Have Sex With Men and Use Injection Drugs
MSM/IDU constitute an estimated 0.35% of the general male population (248,890 men), based on data from NHANES, a general population survey of a probability sample of U.S. households. Other methods for estimating the size of HIV risk behavior populations include meta-analysis of multiple national surveys. NHANES was used because it is the largest national data source available to obtain data on both male-to-male sexual behavior and injection drug use among persons aged ≥18 years.
The findings in this report will be used in CDC's future efforts to refine disease rates by transmission category. The findings demonstrate that, although MSM/IDU constitute only 0.35% of the general male population, they comprise 4%–12% of MSM and 11%–39% of male IDU. One study estimated the prevalence of injection drug use among MSM to be 42%, another estimated the prevalence of male-to-male sex among IDU to be 31%. In 2010, men who have sex with men, inject drugs, or do both represented 71% of persons with new HIV infections in the United States.
The findings in this report are subject to at least five limitations. First, using NHANES to estimate the population proportion of MSM/IDU might provide an underestimate or overestimate because institutionalized and nonhousehold-based populations are not included in the sampling strategy. Second, during 1999–2008, the response rate for sampled male participants with both an interview and a medical examination ranged from 69% in the 2001–2002 data to 72% in the 2007–2008 data, and it is unknown whether an underestimate or overestimate of the proportion of MSM/IDU would result from nonresponse. Third, MSM/IDU from the HIV surveillance systems might not be representative of all MSM/IDU in the United States (e.g., those not infected with HIV). Fourth, some participants might not have accurately reported their behaviors, which might result in underestimates of proportions of MSM/IDU. Finally, the NHSS data were adjusted statistically to account for diagnosed cases with a missing transmission category. The degree of uncertainty introduced by this imputation is unknown.
Because MSM/IDU engage in both of the HIV risk behaviors considered in this analysis, they are particularly vulnerable to infection and can transmit HIV through sexual behavior or by sharing syringes. This analysis demonstrates that the population proportion of MSM/IDU is small, but it comprises a considerable proportion of both MSM and IDU populations at risk for or infected with HIV. For persons at increased risk, such as MSM or IDU, HIV testing at least once a year is recommended. An integrated prevention services approach for IDU should include 1) substance abuse and mental health treatment; 2) risk reduction programs and messages, including interventions to reduce risky sexual behaviors; and 3) access to condoms and sterile injection and drug preparation equipment. Risk reduction programs and interventions targeted toward male IDU populations might be more effective if they incorporate messages about male-to-male sex because approximately 11%–39% of IDU also engage in male-to-male sex according to this analysis. Preexposure prophylaxis (e.g., daily doses of tenofovir disoproxil fumarate and emtricitabine) is also an appropriate prevention strategy for some high-risk IDU and MSM, The National HIV/AIDS Strategy calls for intensified HIV prevention efforts in the communities where HIV is most heavily concentrated, including blacks/African Americans, Hispanics/Latinos, gay and bisexual men, and substance abusers. CDC's High Impact Prevention strategy expands efforts to prevent HIV infection using a combination of effective, scalable, and evidence-based approaches that address male-to-male sex and injection drug use behaviors that might reduce HIV infections among MSM/IDU.
Editorial Note
MSM/IDU constitute an estimated 0.35% of the general male population (248,890 men), based on data from NHANES, a general population survey of a probability sample of U.S. households. Other methods for estimating the size of HIV risk behavior populations include meta-analysis of multiple national surveys. NHANES was used because it is the largest national data source available to obtain data on both male-to-male sexual behavior and injection drug use among persons aged ≥18 years.
The findings in this report will be used in CDC's future efforts to refine disease rates by transmission category. The findings demonstrate that, although MSM/IDU constitute only 0.35% of the general male population, they comprise 4%–12% of MSM and 11%–39% of male IDU. One study estimated the prevalence of injection drug use among MSM to be 42%, another estimated the prevalence of male-to-male sex among IDU to be 31%. In 2010, men who have sex with men, inject drugs, or do both represented 71% of persons with new HIV infections in the United States.
The findings in this report are subject to at least five limitations. First, using NHANES to estimate the population proportion of MSM/IDU might provide an underestimate or overestimate because institutionalized and nonhousehold-based populations are not included in the sampling strategy. Second, during 1999–2008, the response rate for sampled male participants with both an interview and a medical examination ranged from 69% in the 2001–2002 data to 72% in the 2007–2008 data, and it is unknown whether an underestimate or overestimate of the proportion of MSM/IDU would result from nonresponse. Third, MSM/IDU from the HIV surveillance systems might not be representative of all MSM/IDU in the United States (e.g., those not infected with HIV). Fourth, some participants might not have accurately reported their behaviors, which might result in underestimates of proportions of MSM/IDU. Finally, the NHSS data were adjusted statistically to account for diagnosed cases with a missing transmission category. The degree of uncertainty introduced by this imputation is unknown.
Because MSM/IDU engage in both of the HIV risk behaviors considered in this analysis, they are particularly vulnerable to infection and can transmit HIV through sexual behavior or by sharing syringes. This analysis demonstrates that the population proportion of MSM/IDU is small, but it comprises a considerable proportion of both MSM and IDU populations at risk for or infected with HIV. For persons at increased risk, such as MSM or IDU, HIV testing at least once a year is recommended. An integrated prevention services approach for IDU should include 1) substance abuse and mental health treatment; 2) risk reduction programs and messages, including interventions to reduce risky sexual behaviors; and 3) access to condoms and sterile injection and drug preparation equipment. Risk reduction programs and interventions targeted toward male IDU populations might be more effective if they incorporate messages about male-to-male sex because approximately 11%–39% of IDU also engage in male-to-male sex according to this analysis. Preexposure prophylaxis (e.g., daily doses of tenofovir disoproxil fumarate and emtricitabine) is also an appropriate prevention strategy for some high-risk IDU and MSM, The National HIV/AIDS Strategy calls for intensified HIV prevention efforts in the communities where HIV is most heavily concentrated, including blacks/African Americans, Hispanics/Latinos, gay and bisexual men, and substance abusers. CDC's High Impact Prevention strategy expands efforts to prevent HIV infection using a combination of effective, scalable, and evidence-based approaches that address male-to-male sex and injection drug use behaviors that might reduce HIV infections among MSM/IDU.