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  XIX International AIDS Conference
July 22-27, 2012
Washington, DC
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HIV Prevalence and Risks in a New Generation of US Injection Drug Users
  XIX International AIDS Conference, July 22-27, 2012, Washington, DC

Mark Mascolini

Injection drug users (IDUs) under 30 had less than half the HIV prevalence of older IDUs, according to results of a 10,000-person survey by the Centers for Disease Control (CDC) in 2009 [1]. But younger IDUs were more likely to engage in dangerous sexual and injection behaviors than their older counterparts, a finding suggesting they run a higher risk of acquiring and transmitting HIV.

Rate of HIV infection attributable to injection drug use have been dwindling in the United States, but some evidence suggests a surge in HIV risk behaviors among younger IDUs. To assess HIV rates and risks in younger versus older IDUs, CDC researchers conducted an anonymous survey of adult IDUs in 20 metropolitan areas from June through December 2009.

The survey included 798 men and 383 women from 18 to 30 years old, and 6491 men and 2401 women older than 30. Compared with older IDUs, a larger proportion of younger IDUs were white (56.7% versus 23.6%) or Hispanic (27.6% versus 20.8%) and a much smaller proportion were black (10.5% versus 51.3%). Higher proportions of younger IDUs than older IDUs were homeless for under 12 months (46.9% versus 41.0%) or more than 12 months (25.5% versus 19.2%), while a higher proportion of older IDUs reported never being homeless (39.9% versus 27.6%).

Compared with older IDUs, younger IDUs had higher odds of several risky drug use and sexual behaviors, at the following odds ratios (OR) (and 95% confidence intervals):

-- Binge drink in past 30 days: OR 1.4 (1.3 to 1.6)

-- Noninjected meth use in past year: OR 1.6 (1.2 to 2.1)

-- Injected daily in past year: OR 1.3 (1.1 to 1.5)

-- Shared syringes to inject drugs in past year: OR 2.1 (1.9 to 2.4)

-- Shared syringes to divide drugs in past year: OR 1.4 (1.3 to 1.6)

-- Shared cooker, filter, or water in past year: OR 1.8 (1.6 to 2.1)

-- Had first sex at 17 or younger: OR 2.2 (1.7 to 2.7)

-- Had unprotected vaginal/anal sex in past year: OR 2.9 (2.4 to 3.4)

-- Had multiple opposite-sex partners in past year: OR 1.9 (1.7 to 2.1)

-- Last sex partner injected drugs: OR 1.5 (1.3 to 1.7)

Older IDUs were more likely to use noninjected crack.

On the other hand, HIV testing and certain protective behaviors were more likely in younger IDUs. Compared with older IDUs, younger IDUs were more likely to get tested for HIV in the past year (OR 1.2, 95% CI 1.1 to 1.3), to be in an alcohol or drug treatment program in the past year (OR 1.9, 95% CI 1.6 to 2.1), and to purchase sterile needles from pharmacies (OR 2.3, 95% CI 2.1 to 2.6). The CDC recommends yearly testing for IDUs, but only half of younger and older surveyed IDUs reported getting tested in the past 12 months.

Anonymous testing showed that HIV prevalence among older IDUs stood at 10%, compared with 4% in younger IDUs.

Multivariate logistic regression analysis associated several factors with age under 30 in this sample of IDUs, including male gender (OR 1.5), white race (OR 7.6), Hispanic ethnicity (OR 4.6), homelessness for under 1 year (OR 1.3), homelessness for a year or more (OR 1.4), arrested in past 12 months (OR 1.9), binge drinking in past 30 days (OR 1.3), unprotected vaginal or anal sex in past 12 months (OR 2.1), sharing needles to inject (OR 1.2), buying sterile needles from pharmacy (OR 1.5), and being in alcohol or drug treatment program in past year (OR 1.4).

Overall, results show a shifting demographic in younger US IDUs, with growing proportions of whites and Hispanics compared with blacks, and with an array of greater lifestyle, sexual, and injecting risks than in older IDUs. Homelessness and arrests are more frequently among younger IDUs. But younger IDUs do get tested for HIV more than older IDUs, they do join drug and alcohol treatment programs more often, and they do buy clean needles.

The CDC proposed that "HIV prevention programs targeting young IDUs need to address injection and sexual practices as well as individual vulnerability, such as homelessness."


1. Broz D, Pham H, Wejnert C, Le B, Paz-Bailey G, NHBS Study Group. Prevalence of HIV infection and risk behaviours among younger and older injecting drug users in the United States, 2009. XIX International AIDS Conference. July 22-27, 2012, Washington, DC. Abstract TUPE237.