The death toll from the heroin epidemic has been climbing dramatically in recent years — and the annual rate of overdose deaths nearly doubled between 2011 and 2013, according to a new CDC study.

From 2002 through 2013, heroin use in the United States rose by 63 percent, and the rate of abuse or dependence climbed a staggering 90 percent. Deaths from heroin-related overdoses nearly quadrupled, with more than 8,200 people dying in 2013 alone.

The CDC report says that heroin use has increased across most demographic groups — men and women, most age groups, and across all income levels. Rates of heroin use are still highest among men, those ages 18 to 25, people with income less than $20,000 a year, people in urban areas, and those who do not have health insurance or are on Medicaid. But other groups are turning to the drug, too. “Some of the greatest increases occurred in demographic groups with historically low rates of heroin use: women, the privately insured and people with higher incomes,” the CDC says.

The heroin trend isn’t happening in isolation, the CDC study says. Almost all heroin users — 96 percent — also took at least one other drug, and 61 percent used at least three other drugs. Abuse or dependence on opioid painkillers is the strongest risk-factor for heroin use or addiction, the report says, with cocaine addiction also high on the list. People who are addicted to prescription opioid painkillers are 40 times more likely to use or be addicted to heroin, and 45 percent of people who used heroin were also addicted to painkillers.

Another key reason is that heroin is becoming cheaper and more widely available. According to the DEA, the increase in heroin seizures in the U.S. from 2010 and 2014 rose 81 percent, from 2,763 kilograms to 5,014 kilograms. More and more law enforcement agencies are identifying heroin as their primary drug threat, but the CDC report suggests that health care workers focus on reducing the abuse of painkillers by improving prescribing practices.

The study also recommends that states increase access to “medication-assisted treatment” programs that use methadone, buprenorphine and naltrexone along with behavioral counseling. And it says the rapid rise in heroin-related deaths highlights an “urgent need” to broaden access to naloxone, a drug that can reverse the effects of heroin and opioid overdose.