ATLANTA — The sharp increase in US overdose deaths over the last half-decade has split into two distinct epidemics based on age and type of drug, researchers suggested here at a nationwide drug abuse summit on Tuesday.
Opioid drugs include both prescription painkillers (such as Vicodin or Oxycodone) and illegal heroin. They are involved in about 60% of all deadly overdoses in the US, or about 33,000 people in 2015 — a death toll projected to grow even worse.
Prescription drug supplies have tightened in the last five years, shutting down "doctor shopping" for pills and "pill mill" pain clinics. That's led many people addicted to painkillers to switch to heroin. (The US yearly records about 300 million prescriptions of opioid painkillers, 80% of the world total, with more than 2 million people estimated as addicted.)
But "the pills to heroin story can't explain everything," said medical epidemiologist Jay Unick of the University of Maryland, Baltimore County, at the National RX Drug Abuse and Heroin Summit in Atlanta.
In a new analysis of overdose patient and emergency room data, Unick found that among younger drug users, heroin addiction appears to have split off as a phenomenon from the larger prescription painkiller epidemic, with deaths increasing fastest among people in their 20s. The approximately 15,000 people who die from painkiller overdoses, meanwhile, tend to be older, concentrated among people in their 50s and early 60s.
"The heroin epidemic both overlaps and diverges from the prescription one," he said.
Largely, younger people are the ones switching from pills to heroin, or just starting on the drug, Unick suggested, while older people aren't.
Heroin overdose rates have worsened since 2014 as synthetic opioids even more potent than heroin have been laced into street drugs. Fentanyl, for example, killed Prince last year, reportedly in a counterfeit pain pill. It is 30 to 50 times more potent than heroin, but much cheaper for drug dealers to buy and split into doses.
That same potency ties it to "skyrocketing death rates" in New England states, epidemiologist Traci Green of Boston Medical Center noted at a separate presentation at the summit. "They don't even have time to pull the needle and they are out," she said.
(Green warned at the summit that fentanyl is increasingly turning up in cocaine in Rhode Island, separate from heroin use, a worrisome development as people addicted to coke might not be afraid of overdosing. There are about 1.5 million US cocaine users.)
But fentanyl can't explain all the increases in heroin deaths, Unick noted, pointing out that the increases started in 2011, years ahead of fentanyl's debut. And the distribution of fentanyl deaths is uneven among states, concentrated in New England and Eastern ones, some of which have high prescription painkiller death rates and some of which don't.
One possibility behind worsening heroin overdose deaths isn't the potency of fentanyl, but instead shake-ups in the illegal drug supply. That might lead to wide swings in the strength of heroin doses sold to addicts, suggested epidemiologist Daniel Ciccarone of the University of California, San Francisco.
People who take opioids build a tolerance to the drug, requiring them to use larger and larger doses. But variability in heroin potency might leave them exposed to an overdose if what they think is a safe dose is actually loaded with a more powerful synthetic opioid.
"It might be the variability that is the problem," Ciccarone said.
He and colleagues have interviewed heroin users in Baltimore and Massachusetts, for example, and found that some are starting to take precautionary measures when injecting heroin because of fentanyl. They're also reporting continuing changes in what is sold as "heroin" on the street.
Whatever the cause for increased heroin overdoses among young people, Unick's fear is that public health officials might miss the reasons for a heroin boom separate from one tied to taking prescription pills.
"I think there are social network effects that we can't see very well," he told BuzzFeed News. "People have to learn to inject heroin from people they know and trust. It might be that older people just don't want to do that as much."