As Drug Overdose Deaths Escalate, Opioids Continue to Be the Top Killer

— -- As the drug and opioid epidemic escalates in the U.S., a new study has identified the 10 drugs most associated with fatal overdoses.

The study, published today in the National Vital Statics report by the Centers for Disease Control and Prevention found that more than 47,000 people in the U.S. died from drug overdoses in 2014 — an increase from more than 38,000 in 2010. Opioid drugs continue to be linked to the highest percentage of these deaths.

The report may spur public health officials and other leaders to focus more on responding to the growing addiction and drug abuse problem, said Dr. Caleb Alexander, a co-director for the Johns Hopkins Center for Drug Safety and Effectiveness.

The data "should give patients and providers and policymakers pause," he said. "They underscore the seriousness of the overdose epidemic."

The study's researchers, from the National Center for Health Statistics and the Food and Drug Administration, found that the most frequently mentioned drugs on death certificates in fatal drug overdoses were multiple forms of opioids, stimulants and a class of drugs called benzodiazepines, often used to treat anxiety or insomnia. The researchers examined federal data from death certificates from 2010 to 2014.

The 10 most abused drugs on those death certificates were listed in this order: heroin, oxycodone, methadone, morphine, hydrocodone, fentanyl, cocaine, methamphetamine and two benzodiazepines called alprazolam (a common brand name is Xanax) and diazepam (a common brand name is Valium).

Despite work to combat rising numbers of fatal overdoses in the U.S. in recent years, deaths associated with all these drugs, except methadone, increased during the study period.

However, the authors clarified, it is possible that some of the increase may be due to improvements in reporting on death certificates.

Opioids remained the leading cause of overdose deaths, according to the period and data reviewed in the study, but the specific opioid drugs responsible for the fatal overdoses changed. From 2010 to 2011 oxycodone, a prescription drug, was the leading drug linked to overdose deaths. In the following years the illicit drug heroin caused the most drug overdose deaths.

From 2010 through 2014, the number of drug overdose deaths per year increased nearly 23 percent, from 38,329 to 47,055, according to the CDC.

In the same period, deaths associated with heroin use more than tripled, from 3,020 to 10,863.

"I think that these findings are important and another indication of just how serious of an issue this is," Alexander told ABC News today.

"Opioids are responsible for a disproportionate number of injuries and deaths," he said. "It's only natural that policymakers and public health officials focus on opioids."