Research indicates that SUD treatment,136 sterile syringe programs,137 community-based outreach, testing, and linkage to comprehensive care for HIV and other infections138–140 are the most effective ways to reduce transmission among individuals who use drugs. Because these individuals often face barriers to testing, treatment, and adhering to ART, unique supports are needed for prevention and treatment within this population.107
Pre-exposure prophylaxis (PrEP)
PrEP is an important component of HIV prevention. In this approach, people who are at significant risk but not infected with HIV take a daily oral dose of medication to prevent them from contracting the virus.141 The World Health Organization recommends PrEP as one component of prevention for individuals at high risk for HIV.142 As with all medications, adherence is critical to effectiveness.143,144 There have been some promising results of PrEP among people who inject drugs, with one clinical trial finding that it decreased the risk of HIV infection by as much as 84 percent for those who were highly adherent, but only about 50 percent overall.145 More research is needed on optimizing PrEP adherence and the best ways to integrate it into SUD treatment.146 Despite research indicating that PrEP is generally safe and effective for those who are at significant risk of HIV infection,107 strategies to increase access to PrEP among injection drug users should be explored.143,14
The Seek, Test, Treat, and Retain (STTR) Model of Care
People continue to be infected by HIV through unsafe contact with others who are either unaware that they have the virus or have inadequately suppressed their viral load.148 The STTR model of care is specifically designed to address these two drivers of new HIV infections, particularly considering the well-documented delays in testing and treatment experienced by individuals with substance use disorders.149 This approach involves reaching out to high-risk, hard-to-reach drug-using populations who have not recently been tested for HIV (seeking); engaging them in HIV testing (testing); initiating, monitoring, and maintaining ART for those testing positive (treating); and retaining patients in care (retaining).
Incorporating rapid on-site HIV testing into SUD treatment is an important component of efforts to identify those who are infected, initiate care earlier, and reduce transmission.150 However, treatment programs may not have sufficient resources to provide HIV testing. Reducing barriers by providing start-up costs and staff training on how to support individuals who test positive, and addressing staffing needs are crucial to establishing and maintaining rapid on-site HIV testing in SUD treatment facilities.150 Researchers estimate that testing people who inject drugs for HIV every 6 months is cost effective, compared with annual testing, at $133,200 in incremental costs per quality-adjusted life year gained.151
ART has improved the survival of people with HIV, including those who inject drugs, so that they now tend to live as long as those who are not infected with the virus.152 Most patients, regardless of injection drug use history, can achieve viral suppression with ART,153 which can significantly reduce transmission of HIV to others.138 This approach, called Treatment as Prevention, is a crucial part of efforts to reduce the spread of the virus and a key component of the STTR strategy. The Treatment as Prevention approach relies on identifying undiagnosed individuals, linking them to treatment with ART, and retaining them in care.138 Retention in treatment is key to achieving full viral suppression (i.e., virus is below detectable levels) and preventing transmission of HIV. CDC estimates that 49 percent of people with HIV in the United States had full viral suppression in 2014.154 Data from 2011 showed that among people whose viral load was not suppressed, 20 percent had never been diagnosed with HIV, 66 percent were diagnosed but not engaged in medical care for HIV, 4 percent were engaged in HIV medical care but not prescribed ART, and 10 percent were prescribed ART but had not achieved viral suppression.155
Substance Use Disorder Treatment
Studies find that behavioral treatments such as cognitive behavioral therapy and motivational interviewing not only reduce drug use but also improve adherence to ART regimens156 and medications for HCV.157 Among men who have sex with men (MSM), SUD treatment is associated with reduced drug use and risky sexual behavior, and those with HIV report improvements in viral load.158 Addiction pharmacotherapies also reduce the risk for HIV. Pooled results from multiple studies indicate that methadone or buprenorphine treatment for opioid use disorder is associated with a 54 percent reduction in risk of HIV infection among people who inject drugs.136 HIV-infected people who inject drugs are more likely to initiate ART when engaged in methadone treatment.159 Because people who inject drugs also have a relatively high prevalence of mental illness, research suggests that fully integrated addiction, psychiatric, and HIV care might increase the likelihood of ART adherence and improve health outcomes.160,161