Across the globe, the HIV epidemic is inextricably linked to addiction and injection drug use. But even non-illicit drugs like alcohol and cigarettes lead to an increased risk of HIV transmission and worse outcomes among people living with HIV.
Speaking at the 2019 Conference on Retroviruses and Opportunistic Infections (CROI), four researchers summarized the most up-to-date data on addiction epidemics and HIV in a session aptly titled "Adding Fuel to the Fire: Substance Use and HIV."
The first half of the session addressed two contemporary drug use behaviors that are reigniting the HIV epidemic. The first and most obvious driver of HIV is the dramatic rise in opioid addiction fueled by overprescribing of prescription painkillers in the United States. Another contemporary HIV risk behavior is chemsex, which has been enabled by the ubiquity of networking apps.
The latter half of the session focused on age-old addiction disorders that are often overlooked but are equally important factors to consider in the context of ending the HIV epidemic: alcohol and cigarettes.
Collectively, the opioid epidemic, chemsex, alcohol consumption, and cigarette smoking are all increasing the likelihood of HIV transmission and shortening the lives of people already living with HIV. And in each case, a clear path toward progress is hampered by the stigma surrounding the addiction coupled with the stigma associated with HIV.
Opioids and Chemsex: Modern Epidemics Reigniting the HIV Epidemic
The opioid epidemic has created a new generation of injection drug users. From 2004 to 2014, rates of drug treatment admission for opioid injection rose 622% among young people aged 18 to 29.
"I argue there will be a re-starting of the HIV epidemic among people who inject drugs,"said Ricky N. Bluthenthal, Ph.D., with the Institute for Prevention Research, Keck School of Medicine, University of Southern California.
In prior generations, clusters of injection drug–related infections and overdoses were confined to big cities. Today, the epidemic is harder to track and control, because its victims could include anyone who has ever been prescribed an opioid painkiller by their doctor.
"We are not prepared for this problem," he said. "Even when people don't transition to heroin, they're still injecting these prescription opiates," meaning we will continue to see HIV outbreaks in novel locations, Bluthenthal continued.
Unlike the opioid epidemic, the phenomenon of "chemsex," or taking party drugs prior to sexual intercourse, has only been documented in a small subpopulation of men who have sex with men (MSM). Nevertheless, chemsex is a trend that's growing worldwide, enabled by the proliferation of apps that make it easy for curious strangers to convene.
Chemsex "is difficult to define because it's socially constructed," said Mark Rohan Pakianathan, M.D., of St. George's University Hospital, London.
"The substances can vary depending on where you are," Pakianathan said. For example, in Spain, cocaine is a popular chemsex drug; in Thailand, methamphetamine; and in the UK, GHB is the drug of choice.
Two studies -- the MACS cohort and the AURAH study -- have linked chemsex use to greater risk behaviors, such as condomless sex. Pakianathan's own research found that MSM who told their doctors about prior chemsex had a staggeringly higher rate of new HIV, hepatitis C, and other sexually transmitted infections.
Though pre-exposure prophylaxis (PrEP) has been proposed as a way to prevent new HIV infections among people who inject drugs and people who engage in chemsex, neither Bluthenthal nor Pakianathan was very hopeful that this intervention is the best path forward. Both pointed to data that drew mixed conclusions about adherence, and Pakianathan pointed to alarming case reports of fatal interactions between antiretroviral therapy and chemsex drugs.
For Bluthenthal, who has 30 years' experience with HIV and opioid use disorder interventions, the solutions to stemming the re-emergence of HIV due to injection drug use are obvious: opioid replacement therapy, needle exchange, and safe injection sites.
The challenge, he said, is to implement those solutions at a scale that matches the severity of the epidemic.
Alcohol and Tobacco: Double Jeopardy of HIV Transmission and Outcomes
Though often overlooked, alcohol and cigarette addiction are more prevalent among people living with HIV compared to the general population. Not only do they worsen health outcomes for people with HIV, but they are also thought to be major risk factors for HIV transmission.
According to Leickness Chisamu Simbayi, M.Sc., D.Phil, with the Human Sciences Research Council in Cape Town, South Africa, the alcohol epidemic is "hidden in plain sight." A 2007 meta-analysis showed that people who drink alcohol in excess are more likely to be HIV positive than non-drinkers.
Simbayi compared two heat maps of the globe, pointing out that countries with high levels of excessive alcohol consumption tend to have high rates of HIV infection. Chiefly, those countries are in Eastern Europe, including Russia, and in Sub-Saharan Africa.
Like other drugs, alcohol lowers inhibitions and impairs decision-making, increasing the likelihood of HIV infection. For those who are already living with HIV, alcoholism can lead to worse outcomes. Alcohol affects cellular structure and has been shown to accelerate HIV disease progression.
For Simbayi, the solution is to combine evidence-based harm reduction strategies with government-led efforts to stem alcohol consumption, such as higher taxes and an older legal drinking age.
Smoking follows a similar pattern in terms of HIV risk. Although rates of smoking vary greatly from country to country, people with HIV seem to smoke at a higher rate.
"Regardless of where you live in the world, it's been shown that the rate of smoking in people living with HIV is two to three times higher," said Lene Ryom, M.D., Ph.D., of the Centre of Excellence for Health, Immunity and Infections in Copenhagen, Denmark.
While there isn't any evidence to support a link between smoking and seroconversion, there's ample evidence to support the idea that smoking harms people living with HIV. Smoking might enhance viral replication, increase the formation of free radicals, impair the adaptive immune response, and increase inflammation, Ryom said. According to the 2010 SMART study, smokers with HIV were more than two times as likely to die compared to former smokers.
According to Ryom, it's important for clinicians to continuously support smoking cessation among their patients. If patients are motivated to quit, the most effective strategy is a combination of pharmacotherapy -- patches or other replacement therapy -- plus cognitive behavioral therapy.
Ultimately, Simbayi and Ryom stressed that alcohol and smoking are major risk factors in the HIV epidemic that are commonly overlooked by the health care system and underestimated by individual care providers.
While it's not entirely clear why people with HIV are more likely to experience substance use disorders, possible drivers include stigma, internalized homophobia, low self-esteem, and the minority stress hypothesis, Pakianathan said.
"We've got to clean up our language and begin treating people like people," said Bluthenthal, referring to people addicted to opioids. "Drug users are people too. We've got to act like that."