The National Vital Statistics System multiple cause-of-death mortality files were used to identify drug overdose deaths.* Drug overdose deaths were classified using the International Classification of Disease, Tenth Revision (ICD-10), based on the ICD-10 underlying cause-of-death codes X40–44 (unintentional), X60–64 (suicide), X85 (homicide), or Y10–Y14 (undetermined intent) (2). Among the deaths with drug overdose as the underlying cause, the type of opioid involved is indicated by the following ICD-10 multiple cause-of-death codes: opioids (T40.0, T40.1, T40.2, T40.3, T40.4, or T40.6); natural and semisynthetic opioids (T40.2); methadone (T40.3); synthetic opioids, other than methadone (T40.4); and heroin (T40.1). Some deaths involve more than one type of opioid; these deaths were included in the rates for each category (e.g., a death involving both a synthetic opioid and heroin would be included in the rates for synthetic opioid deaths and in the rates for heroin deaths). Age-adjusted death rates were calculated by applying age-specific death rates to the 2000 U.S standard population age distribution (3). Significance testing was based on the z-test at a significance level of 0.05.
During 2014, 47,055 drug overdose deaths occurred in the United States. Since 2000, the age-adjusted drug overdose death rate has more than doubled, from 6.2 per 100,000 persons in 2000 to 14.7 per 100,000 in 2014 (Figure 1). The overall number and rate of drug overdose deaths increased significantly from 2013 to 2014, with an additional 3,073 deaths occurring in 2014 (Table), resulting in a 6.5% increase in the age-adjusted rate. From 2013 to 2014, statistically significant increases in drug overdose death rates were seen for both males and females, persons aged 25–34 years, 35–44 years, 55–64 years, and ≥65 years; non-Hispanic whites and non-Hispanic blacks; and residents in the Northeast, Midwest and South Census Regions (Table). In 2014, the five states with the highest rates of drug overdose deaths were West Virginia (35.5 deaths per 100,000), New Mexico (27.3), New Hampshire (26.2), Kentucky (24.7) and Ohio(24.6).† States with statistically significant increases in the rate of drug overdose deaths from 2013 to 2014 included Alabama, Georgia, Illinois, Indiana, Maine, Maryland, Massachusetts, Michigan, New Hampshire, New Mexico, North Dakota, Ohio, Pennsylvania, and Virginia.
In 2014, 61% (28,647, data not shown) of drug overdose deaths involved some type of opioid, including heroin. The age-adjusted rate of drug overdose deaths involving opioids increased significantly from 2000 to 2014, increasing 14% from 2013 (7.9 per 100,000) to 2014 (9.0) (Figure 1). From 2013 to 2014, the largest increase in the rate of drug overdose deaths involved synthetic opioids, other than methadone (e.g., fentanyl and tramadol), which nearly doubled from 1.0 per 100,000 to 1.8 per 100,000 (Figure 2). Heroin overdose death rates increased by 26% from 2013 to 2014 and have more than tripled since 2010, from 1.0 per 100,000 in 2010 to 3.4 per 100,000 in 2014 (Figure 2). In 2014, the rate of drug overdose deaths involving natural and semisynthetic opioids (e.g., morphine, oxycodone, and hydrocodone), 3.8 per 100,000, was the highest among opioid overdose deaths, and increased 9% from 3.5 per 100,000 in 2013. The rate of drug overdose deaths involving methadone, a synthetic opioid classified separately from other synthetic opioids, was similar in 2013 and 2014.
Discussion
More persons died from drug overdoses in the United States in 2014 than during any previous year on record. From 2000 to 2014 nearly half a million persons in the United States have died from drug overdoses. In 2014, there were approximately one and a half times more drug overdose deaths in the United States than deaths from motor vehicle crashes (4). Opioids, primarily prescription pain relievers and heroin, are the main drugs associated with overdose deaths. In 2014, opioids were involved in 28,647 deaths, or 61% of all drug overdose deaths; the rate of opioid overdoses has tripled since 2000. The 2014 data demonstrate that the United States' opioid overdose epidemic includes two distinct but interrelated trends: a 15-year increase in overdose deaths involving prescription opioid pain relievers and a recent surge in illicit opioid overdose deaths, driven largely by heroin.
Natural and semisynthetic opioids, which include the most commonly prescribed opioid pain relievers, oxycodone and hydrocodone, continue to be involved in more overdose deaths than any other opioid type. Although this category of opioid drug overdose death had declined in 2012 compared with 2011, and had held steady in 2013, there was a 9% increase in 2014.
Drug overdose deaths involving heroin continued to climb sharply, with heroin overdoses more than tripling in 4 years. This increase mirrors large increases in heroin use across the country (5) and has been shown to be closely tied to opioid pain reliever misuse and dependence. Past misuse of prescription opioids is the strongest risk factor for heroin initiation and use, specifically among persons who report past-year dependence or abuse (5). The increased availability of heroin, combined with its relatively low price (compared with diverted prescription opioids) and high purity appear to be major drivers of the upward trend in heroin use and overdose (6).
The rate of drug overdose deaths involving synthetic opioids nearly doubled between 2013 and 2014. This category includes both prescription synthetic opioids (e.g., fentanyl and tramadol) and non-pharmaceutical fentanyl manufactured in illegal laboratories (illicit fentanyl). Toxicology tests used by coroners and medical examiners are unable to distinguish between prescription and illicit fentanyl. Based on reports from states and drug seizure data, however, a substantial portion of the increase in synthetic opioid deaths appears to be related to increased availability of illicit fentanyl (7), although this cannot be confirmed with mortality data. For example, five jurisdictions (Florida, Maryland, Maine, Ohio, and Philadelphia, Pennsylvania) that reported sharp increases in illicit fentanyl seizures, and screened persons who died from a suspected drug overdose for fentanyl, detected similarly sharp increases in fentanyl-relateddeaths (7).§ Finally, illicit fentanyl is often combined with heroin or sold as heroin. Illicit fentanyl might be contributing to recent increases in drug overdose deaths involving heroin. Therefore, increases in illicit fentanyl-associated deaths might represent an emerging and troubling feature of the rise in illicit opioid overdoses that has been driven by heroin.
The findings in this report are subject to at least three limitations. First, several factors related to death investigation might affect estimates of death rates involving specific drugs. At autopsy, toxicological laboratory tests might be performed to determine the type of drugs present; however, the substances tested for and circumstances under which the tests are performed vary by jurisdiction. Second, in 2013 and 2014, 22% and 19% of drug overdose deaths, respectively, did not include information on the death certificate about the specific types of drugs involved. The percent of overdose deaths with specific drugs identified on the death certificate varies widely by state. Some of these deaths might have involved opioids. This increase in the reporting of specific drugs in 2014 might have contributed to some of the observed increases in drug overdose death rates involving different types of opioids from 2013 to 2014. Finally, some heroin deaths might be misclassified as morphine because morphine and heroin are metabolized similarly (8), which might result in an underreporting of heroin overdose deaths.
To reverse the epidemic of opioid drug overdose deaths and prevent opioid-related morbidity, efforts to improve safer prescribing of prescription opioids must be intensified. Opioid pain reliever prescribing has quadrupled since 1999 and has increased in parallel with overdoses involving the most commonly used opioid pain relievers (1). CDC has developed a draft guideline for the prescribing of opioids for chronic pain to address this need.¶
In addition, efforts are needed to protect persons already dependent on opioids from overdose and other harms. This includes expanding access to and use of naloxone (a safe and effective antidote for all opioid-related overdoses)** and increasing access to medication-assisted treatment, in combination with behavioral therapies (9). Efforts to ensure access to integrated prevention services, including access to syringe service programs when available, is also an important consideration to prevent the spread of hepatitis C virus and human immunodeficiency virus infections from injection drug use.
Public health agencies, medical examiners and coroners, and law enforcement agencies can work collaboratively to improve detection of outbreaks of drug overdose deaths involving illicit opioids (including heroin and illicit fentanyl) through improved investigation and testing as well as reporting and monitoring of specific drugs, and facilitate a rapid and effective response that can address this emerging threat to public health and safety (7). Efforts are needed to distinguish the drugs contributing to overdoses to better understand this trend.
1Division of Unintentional Injury Prevention, National Center for Injury Prevention and Control, CDC.
Corresponding author: Rose A. Rudd, rvr2@cdc.gov, 770-488-3712.
References
, MSPH1; , JD1; , PhD1; R. , PhD1
* Additional information available at http://www.cdc.gov/nchs/nvss/mortality_public_use_data.htm.
† Additional information available at http://www.cdc.gov/drugoverdose/data/statedeaths.html.
§ Additional information available at http://pub.lucidpress.com/NDEWSFentanyl/
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¶ Additional information available at http://www.cdc.gov/drugoverdose/prescribing/guideline.html.
** Additional information available at https://store.samhsa.gov/shin/content/SMA13-4742/Overdose_Toolkit_2014_Jan.pdf 
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