Fatal drug overdoses more than doubled since 1999, CDC finds Middle aged adults were most at risk for fatal overdoses.

 -- The rate of fatal drug overdoses in the U.S. more than doubled since 1999, outpacing suicide and car accidents in 2015 as a cause of death, according to a new report by the Centers for Disease Control and Prevention.

CDC researchers examined data from the National Vital Statics System to see the effects of drug trends across the nation from 1999 to 2015.

Rates of fatal drug overdoses have dramatically increased since 1999, rising from 6.1 deaths per 100,000 people to 16.3 deaths per 100,000 in 2015, according to the CDC report.

That number is higher than the rate of death for suicides in the U.S., 13.4 deaths per 100,000, or the rate of death from car accidents, 11.1 deaths per 100,000 residents.

The overall number of deaths due to opioid overdoses quadrupled during the same time period, according to figures previously published by the CDC. Opioids killed more than 33,000 people in 2015, more than any year on record, according to the CDC, which estimates that 91 Americans die every day from an opioid overdose.

Some 500,000 Americans died from 2000 to 2015 as a result of the opioid epidemic, the CDC says.

People in all age groups were more at risk for dying from drug overdoses but those between their mid-40s and their 60s were hardest hit, according to the new report.

And despite persistent concerns over teens and young adults abusing drugs, middle-aged adults were the most likely to suffer a fatal overdose, according to the report.

People between the ages of 54 to 65 saw the biggest percent increase in fatal drug overdoses during the study period, rising nearly five-fold from 4.2 deaths per 100,000 to 21.8 deaths in 2015.

Americans between the ages of 45 to 54 had the highest rate of fatal drug overdoses overall in 2015, with 30 deaths reported per 100,000.

Dr. Caleb Alexander, a co-director for the Johns Hopkins Center for Drug Safety and Effectiveness, said the report shows overdose deaths related to opioids are increasing at an "incredible rate"

"Each year I think it's hard to imagine it getting much worse and yet last year we had the highest number of deaths on record," Alexander said.

Alexander pointed out that the data highlighted how many people the drugs have impacted from across various age groups.

"Sometimes there's this perception that this is a problem of only teenagers or young adults and nothing could be further from the truth," Alexander said. "Middle aged and elderly adults are also being affected by the epidemic."

The deadly spread of illicit opioids were also reflected in the numbers. The percentage of fatal overdoses related to heroin more than tripled from 8 percent in 2010 to 25 percent in 2015. Synthetic opioids also took a heavy toll accounting for 18 percent of fatal overdose deaths in 2015 up from 8 percent in 2010.

But the increase was not all due to opioids, the percent of drug deaths from cocaine increased slightly to 13 percent in 2015 compared to 11 percent in 2010.

The percentage of overdose deaths due to natural and semisynthetic opioids -- which includes prescription heroin drugs oxycodone and hydrocodone -- decreased from 29 percent in 2010 to 24 percent in 2015.

In 2015 the states hardest hit by fatal drug overdoses were West Virginia with 41.5 deaths per 100,000 people, New Hampshire (34.3), Kentucky (29.9) and Ohio (29.9.)

Dr. Corey Slovis, chairman of department of emergency medicine at Vanderbilt University Medical Center and medical director of the National Fire Department and National Airport, said the current drug epidemic is "the worst that I've ever seen it."

With opioid use increasing, Slovis said emergency services has had a hard time responding to all the overdose calls.

"It's that it's not just heroin anymore between the fentanyl [and] of the synthetic variants including carfentanil" an elephant tranquilizer, said Slovis.

Slovis said some illicit synthetic opioids can be 50 to 100 times more potent than heroin.

Fentanyl and Carfentanil, which was designed to be an elephant tranquilizer, has led in some instances to EMS personnel running out of the opioid antidote Narcan while treating a single patient, he said. Rather than use one or two doses they're using 10 doses to try and save a patient's life.

"When you use an elephant tranquilizer on a human, bad things are going to happen," Slovis said, explaining EMS personnel had to double the amount of Narcan they bring with them in the field.

Shelly Prasad Chawla contributed to this article. She is a resident physician of Internal Medicine in Chicago and a resident in the ABC News Medical Unit.