Will there be a new wave of HIV in people who inject drugs in the US?

Ever since there was an outbreak of HIV among white, largely rural heroin users in Indiana in 2015, there have been concerns that the conditions exist in some parts of the US for more outbreaks among heterosexual people who inject drugs.

While there is little evidence yet for a crossover of HIV from men who have sex with men (MSM) who inject drugs to heterosexuals, several presentations at last week's Conference on Retroviruses and Opportunistic Infections (CROI 2017) in Seattle found that the conditions do exist for it to happen. And they find a new generation of heterosexual people who inject drugs (PWID) who are not connected to conventional drug services, are sharing needles, and are increasingly interested in methamphetamine.

Meanwhile, studies among MSM found that while injecting methamphetamine is in decline among the white MSM population, it is increasing in black MSM.

Increasing methamphetamine injection in heterosexuals

Evidence from Seattle’s local authority, King County in Washington State, sends warning signs that conditions do exist for a crossover of HIV from MSM to heterosexuals due to a rise in heterosexuals injecting methamphetamine – and evidence that a significant proportion are sharing needles with MSM.

Sara Glick from the University of Washington in Seattle said that at present HIV prevalence in MSM who inject drugs is very high at 35-40%, but is only 3% in heterosexual PWID.

Two different behavioural surveillance programmes of PWID – the Seattle Area section of the National HIV Behavioral Surveillance (NHBS) of Injecting Drug Users, and the King County Syringe Exchange Program survey – looked at the proportion of people injecting drugs in the last year who had injected methamphetamine. The survey included only those who had been sexually active in the past year.

In MSM, methamphetamine was not unexpectedly the prominent drug of choice. In the NHBS survey the proportion of injecting MSM who used methamphetamine rose from 55% in 2005 to over 80% in 2009 and stayed at that level thereafter. In the King County survey methamphetamine was used by over 80% of MSM who inject drugs from 2013 onwards.

In contrast the use of methamphetamine by heterosexual PWID, who had previously mainly used opiates, has been sharply increasing. In heterosexual PWID the proportion using methamphetamine rose from 24% in 2009 to 69% in 2015 and in the King County survey from 16% to 57%. In women who inject drugs, meth usage rose similarly from 26% to 65% in the NHBS survey and 25% to 61% in the King County one.

The pattern of usage is somewhat different in heterosexuals. MSM are more likely to inject methamphetamine by itself, but heterosexuals were more likely to inject it alongside heroin in a so-called ‘goofball’. By 2015 47% of heterosexual males who inject drugs reported goofball injection while only 10% reported using methamphetamine alone. The proportions were similar for women (43% versus 17%).

However, goofball injection also became more popular among MSM too, reported by only 18% of MSM who inject drugs (24% of meth users) in 2009 but by 34% of MSM who inject drugs (41% of meth users) by 2015.

Of most concern is that sharing is occurring between MSM and heterosexuals. In MSM who admitted sharing injection equipment, their last sharing partner had been a woman in 31% of cases and a heterosexual man in 14%. In females who inject drugs, their last sharing partner had been a man who has sex with a man in 15% of cases and in heterosexual men, 7% of cases.

Prescription painkillers as a gateway to injecting

Dita Broz from the Centers for Disease Control (CDC) provided some troubling evidence that since 2000 a massive increase in the number of people with addictions to orally-dosed opioid painkillers has led directly to a new generation of injectors.

Deaths from overdoses of opioid drugs have increased in the adult population from three per 100,000 in 2001 to 10.4 per 100,000 (one per every 9600 US adults per year) in 2015, and the steepest increase has been among non-conventional medical opioid such as fentanyl, with a tenfold increase. Medically prescribed opioids (including methadone) are responsible for 4.7 overdose deaths per 100,000 per year.

In order to find out whether non-injected opioid painkiller use was a precursor to injecting opioids, the NHBS conducted a respondent-driven survey of people who had injected opioids in the last year in 16 cities and asked them: “Were you hooked on painkillers before you injected for the first time?”

As this is a respondent-driven sample, there’s no denominator; we can’t tell if respondents were typical of PWID in their area. But there was a large increase in prior prescription opioid use in the last 25 years. In people who first injected opioids before 1995, 12% said they had been hooked on painkillers before they started to inject. In people who had started injecting any year after 2005, that proportion had increased to 50%. The median time between becoming addicted to prescription painkillers and injecting was four years.

One in three PWID (30.5%) said they had obtained the painkillers they became addicted to directly from prescriptions by doctors. Another 40% had got them from a friend or family: half of these had been bought, half given. One in sixteen people (6.7%) had stolen them.

Prior prescription painkiller dependence was 2.9 times more likely in people who had first started to inject after 2000 than in people who had started before that. Also associated with prior painkiller addiction were younger people (under-30s were 70% more likely to have had prior painkiller dependence); being white rather than of other ethnicity (also 70% more likely); and, to some extent, being homeless (20% more likely) and female (10% more likely).

People who had started injecting after 2000 were less likely to have HIV (2% versus 6%), however.

Changing patterns of meth use in gay men

Two surveys looked at trends in methamphetamine use, both injected and non-injected, in MSM in the US. Both found that trends in drug use in gay men in general had stayed flat but that who was using them had changed: use in black and poorer men had increased at almost exactly the same rate as it had decreased in white men.

Brooke Hoots of the CDC said that non-medical prescription opioid use had been reported by about 7.7% of MSM in 2008, 2011 and 2014 and almost the same proportion reported using methamphetamine (8% in 2014). A higher proportion of MSM reported using cocaine, but again with little variation (18.6% in 2008 and 19% in 2014).

More white than black MSM reported prescription opioid use, but while use among white men has been slightly, though not significantly, decreasing (from 10.2% in 2008 to 9.5% in 2014) it has risen significantly, from 4.2% to 5.9%, in black MSM.

There was a similar change related to income: prescription opioid use in MSM earning under $20,000 a year rose from 6.7% to 9.3%, and it fell in MSM earning over $75,000 a year, from 8.5% to 6.4%.

Similar trends were reported specifically from Washington DC, where Irene Kuo of George Washington University found complementary trends in meth use in white and black MSM. In white MSM the proportion in the city who reported using meth in the last year had gone down from 9.5% to 4.7% between 2008 and 2014. In black MSM it had gone up, from 4.4% to 9.9%.

There were encouraging signs in white MSM that young men were not taking to meth: men over 30 were 2.5 times more likely to use meth than those under 30. On the other hand, as the national survey found, it is increasingly becoming a drug of the poor rather than the rich: white MSM earning under $20,000 a year were no less than 8.45 times more likely to use meth than men earning over $50,000 a year.

HIV-positive MSM were 10.6 times more likely to use meth if they were white and 4.2 times more likely if they were black but here, as ever, the question is whether their meth use increased their risk of HIV or their having HIV made them more likely to use meth. Interestingly, there was no significant association between condom use and meth use.

Finally, one interesting study from San Diego looked at what might be called the tertiary effects of opiate substitution therapy (OST). This benefit is that people receiving OST (or medication-assisted therapy as it is known in the US) not only suffer from fewer injection-related ills (primary benefit) and share needles and pass on fewer infections to others (secondary effect) but that they also initiate fewer people into injecting (tertiary benefit).

A group of PWID were asked: “Have you ever helped someone inject who had never injected before?” People on OST programmes were 38% less likely to report that they had.