HIV Infection and HIV-Associated Behaviors Among Injecting Drug Users — 20 Cities, United States, 2009

Despite a recent reduction in the number of human immunodeficiency virus (HIV) infections attributed to injecting drug use in the United States (1), 9% of new U.S. HIV infections in 2009 occurred among injecting drug users (IDUs) (2). To monitor HIV-associated behaviors and HIV prevalence among IDUs, CDC's National HIV Behavioral Surveillance System (NHBS) conducts interviews and HIV testing in selected metropolitan statistical areas (MSAs). This report summarizes data from 10,073 IDUs interviewed and tested in 20 MSAs in 2009. Of IDUs tested, 9% had a positive HIV test result, and 45% of those testing positive were unaware of their infection. Among the 9,565 IDUs with HIV negative or unknown HIV status before the survey, 69% reported having unprotected vaginal sex, 34% reported sharing syringes, and 23% reported having unprotected heterosexual anal sex during the 12 previous months. Although these risk behavior prevalences appear to warrant increased access to HIV testing and prevention services, for the previous 12-month period, only 49% of the IDUs at risk for acquiring HIV infection reported having been tested for HIV, and 19% reported participating in a behavioral intervention. Increased HIV prevention and testing efforts are needed to further reduce HIV infections among IDUs.

NHBS monitors HIV-associated behaviors and HIV prevalence among populations at high risk for acquiring HIV. In 2009, NHBS staff members in 20 MSAs with high prevalence of acquired immunodeficiency syndrome (AIDS)* collected cross-sectional behavioral risk data and conducted HIV testing among IDUs using respondent-driven sampling, a peer-referral sampling method (3,4). Recruitment chains in each city began with one to 15 initial participants recruited by NHBS staff members during formative assessment and planning. Initial participants who completed the interview were asked to recruit up to five other IDUs through use of a coded coupon system designed to track referrals. Recruitment continued for multiple waves; all participation was voluntary. Persons were eligible to participate if they had injected drugs during the previous 12 months, resided in the MSA, and could complete the interview in English or Spanish. After participants gave oral informed consent, in-person interviews were conducted by trained interviewers who administered a standardized, anonymous questionnaire about HIV-associated behaviors. All respondents were offered anonymous HIV testing, which was performed by collecting blood or oral specimens for either rapid testing in the field or laboratory-based testing. A nonreactive rapid test result was considered HIV negative; a reactive rapid test result was considered HIV positive if confirmed by Western blot or indirect immunofluorescence assay. Incentives were offered for participating in the interview, completing an HIV test, and for recruiting IDUs to participate.†

For this report, data on HIV testing and 13 HIV-associated behaviors were analyzed. Participants were asked whether, in the previous 12 months, they 1) had shared syringes; 2) had shared injection equipment other than syringes; 3) had vaginal sex; 4) had unprotected vaginal sex; 5) had heterosexual anal sex; 6) had unprotected heterosexual anal sex; 7) had male-male anal sex; 8) had unprotected male-male anal sex; 9) had more than one opposite sex partner; 10) had been tested previously for HIV infection; and 11) had participated in an HIV behavioral intervention. In addition, participants were asked whether they had ever been tested for 12) HIV or 13) hepatitis C virus (HCV) infection.§ IDUs who tested HIV positive during the survey were defined as unaware of their HIV infection if they had reported that their most recent previous HIV test result was negative, indeterminate, or unknown, or that they had never been tested. IDUs with self-reported negative, indeterminate, or unknown status (including those who tested positive during the survey), were considered to be at risk for acquiring HIV. Data from each MSA were analyzed using a respondent-driven sampling analysis tool that produces estimates adjusted for differences in peer recruitment patterns and size of participant IDU peer networks. Results from these analyses were aggregated and weighted by the size of the IDU population in each MSA (5) to obtain estimates overall.¶

In 2009, a total of 13,186 persons were recruited to participate; of these, 2,687 (20%) were found ineligible. An additional 426 (3%) eligible participants were excluded from analysis.** Data for the remaining 10,073 participants were used in the analysis of HIV prevalence and participant awareness of serostatus (Table 1). To focus the analysis of HIV-associated behaviors on persons at risk for acquiring HIV infection, 508 participants who reported that they previously had tested positive for HIV were excluded (Table 2).

Among 10,073 IDUs, 9% tested positive for HIV. Prevalence of HIV infection was higher among Hispanics (12%) and non-Hispanic blacks (11%) than non-Hispanic whites (6%). IDUs in the Northeast and South regions had higher HIV prevalence (12% and 11%) than those in the Midwest and West regions (5% and 6%). Those with less than a high school education had higher HIV prevalence (13%) than IDUs who completed high school (8%) or had more than high school education (7%) (Table 1). Among HIV-infected IDUs, 45% (95% confidence interval [CI] = 38%–51%) were unaware of their infection.

Among the 9,565 IDUs at risk for acquiring HIV infection and responding to questions regarding HIV-associated behaviors in the previous 12 months, 34% reported sharing syringes, 46% reported multiple opposite sex partners, 69% reported unprotected vaginal sex, and 23% reported unprotected heterosexual anal sex. In addition, 19% reported participating in an HIV behavioral intervention, and 49% reported having had an HIV test (Table 2).

Among the IDUs at risk for acquiring HIV infection, 72% reported ever being tested for HCV infection (Table 2), and 89% (CI = 88%–90%) reported ever having an HIV test. Among male IDUs at risk for acquiring HIV infection, 7% (CI = 5%–8%) reported male-male anal sex in the previous 12 months, and 5% (CI = 3%–7%) reported unprotected male-male anal sex in the previous 12 months.

The prevalence of HIV-associated risk behaviors in the previous 12 months generally decreased with increasing age. For example, among persons aged 18–29 years, 52% reported sharing syringes, compared with 39% aged 30–39 years, 34% aged 40–49 years, and 25% aged ≥50 years. A higher percentage of IDUs with less than a high school education reported sharing syringes (38%), compared with high school graduates (32%) or those with higher education (31%). Lower percentages of IDUs with less than a high school education reported participation in HIV interventions (16%) and testing for HCV infection (67%), compared with those with a high school education (20% and 73%, respectively) and those with higher deducation (24% and 78%, respectively). A higher percentage of those living at or below the federal poverty level (35%) shared syringes than those above the poverty level (27%), and a lower percentage of those living at or below the poverty level had HCV testing (70%) than those above the poverty level (78%) (Table 2).

Reported by

Cyprian Wejnert, PhD, Huong Pham, MPH, Alexandra M. Oster, MD, Elizabeth A. DiNenno, PhD, Amanda Smith, MPH, Nevin Krishna, MS, Amy Lansky, PhD, Div of HIV/AIDS Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, CDC. Corresponding contributor: Cyprian Wejnert, cwejnert@cdc.gov, 404-639-6044.

Editorial Note

The 2009 data in this report provide the first estimates from a large-scale survey of HIV seroprevalence among IDUs since 1993–1997, when CDC conducted anonymous HIV testing among IDUs entering drug treatment centers in 14 MSAs (6). In the study of IDUs entering drug treatment, HIV prevalence was found to be 18% (range by MSA = 1%–37%). In this analysis, 9% of IDUs tested positive for HIV infection. Furthermore, 45% of those testing positive were unaware of their infection.

Risk behavior prevalences in this report showing that IDUs are at risk for acquiring HIV infection through their sexual behavior in addition to their drug use practices are similar to previously reported NHBS surveillance data (7). Compared with a similar analysis of IDUs interviewed during 2005–2006, lower percentages in this 2009 study reported receiving HIV interventions (19% compared with 30%) and HIV testing (49% compared with 66%) in the previous 12 months (7). These results highlight the need for expanded HIV testing and prevention among IDUs. The combination of declining HIV prevalence and high-risk behavior represent a critical intervention opportunity to further reduce HIV prevalence and incidence among IDUs.

Consistent with previous reports (8), this analysis found higher HIV prevalence among Hispanic and non-Hispanic black IDUs than non-Hispanic white IDUs. However, minority IDUs were neither more nor less likely to have received HIV testing, participated in HIV behavioral interventions, or engaged in risk behaviors than white IDUs in the 12 months preceding the NHBS interview. These data suggest factors not assessed by this study might be contributing to racial/ethnic disparities in HIV prevalence among IDUs.

The findings in this report are subject to at least three limitations. First, some participants might not have accurately reported their behavior to interviewers, and results might be affected by social desirability bias. Second, because no method of obtaining probability samples of IDUs exists, the representativeness of the NHBS sample cannot be determined. Although respondent-driven sampling adjusts for some selection biases (4), other biases might have affected the sample. Finally, IDUs were interviewed in 20 MSAs with high AIDS prevalence; findings from these cities might not be generalizable to other cities or states.

To reduce the number of new HIV infections, the National HIV/AIDS Strategy†† calls for intensifying prevention efforts in communities where HIV is most heavily concentrated. CDC's high impact prevention approach§§ is an essential step toward achieving the goals of the national strategy. HIV prevention strategies for IDUs, including HIV testing and linkage to care, prevention and care for HIV-infected IDUs, and access to new sterile syringes,¶¶ have been shown to be effective. Targeted, effective approaches to HIV prevention will help reduce the number of new HIV infections among IDUs.

Acknowledgments

National HIV Behavioral Surveillance System staff members, including Jennifer Taussig, Laura Salazar, Shacara Johnson, Jeff Todd, Atlanta, Georgia; Colin Flynn, Danielle German, Baltimore, Maryland; Debbie Isenberg, Maura Driscoll, Elizabeth Hurwitz, Boston, Massachusetts; Nik Prachand, Nanette Benbow, Chicago, Illinois; Sharon Melville, Richard Yeager, Jim Dyer, Alicia Novoa, Dallas, Texas; Mark Thrun, Alia Al-Tayyib, Denver, Colorado; Emily Higgins, Eve Mokotoff, Detroit, Michigan; Aaron Sayegh, Jan Risser, Hafeez Rehman, Houston, Texas; Trista Bingham, Ekow Sey, Los Angeles, California; Lisa Metsch, Dano Beck, David Forrest, Gabriel Cardenas, Miami, Florida; Chris Nemeth, Lou Smith, Carol-Ann Watson, Nassau-Suffolk, New York; William Robinson, DeAnn Gruber, Narquis Barak, New Orleans, Louisiana; Alan Neaigus, Sam Jenness, Travis Wendel, Camila Gelpi-Acosta, New York, New York; Henry Godette, Barbara Bolden, Sally D'Errico, Newark, New Jersey; Kathleen Brady, Althea Kirkland, Mark Shpaner, Philadelphia, Pennsylvania; Vanessa Miguelino-Keasling, Al Velasco, San Diego, California; Henry Raymond, San Francisco, California; Sandra Miranda De León, Yadira Rolón-Colón, San Juan, Puerto Rico; Maria Courogen, Hanne Thiede, Nadine Snyder, Richard Burt, Seattle, Washington; and Tiffany West-Ojo, Manya Magnus, Irene Kuo, District of Columbia.

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