"The percentage of deaths with concomitant involvement of other drugs varied by drug. For example, almost all drug overdose deaths involving alprazolam or diazepam (96%) mentioned involvement of other drugs. In contrast, 50% of the drug overdose deaths involving methamphetamine, and 69% of the drug overdose deaths involving fentanyl mentioned involvement of one or more other specific drugs.

"Table D shows the most frequent concomitant drug mentions for each of the top 10 drugs involved in drug overdose deaths in 2016.

"For the top 15 drugs:

"• Among drug overdose deaths that mentioned at least one specific drug, oxycodone ranked first in 2011,heroin from 2012 through 2015, and fentanyl in 2016.

"• In 2011 and 2012, fentanyl was mentioned in approximately 1,600 drug overdose deaths each year, but mentions increased in 2013 (1,919 deaths),2014 (4,223 deaths), 2015 (8,251 deaths), and 2016(18,335 deaths). In 2016, 29% of all drug overdose deaths mentioned involvement of fentanyl.

"The number of drug overdose deaths per year increased 54%, from 41,340 deaths in 2011 to 63,632 deaths in 2016 (Table A). From the literal text analysis, the percentage of drug overdose deaths mentioning at least one specific drug or substance increased from 73% of the deaths in 2011 to 85% of the deaths in 2016. The percentage of drug overdose deaths that mentioned only a drug class but not a specific drug or substance declined from 5.1% of deaths in 2011 to 2.5% in 2016.

"• The rate of drug overdose deaths involving synthetic opioids other than methadone, which include drugs such as fentanyl, fentanyl analogs, and tramadol, increased from 0.3 per 100,000 in 1999 to 1.0 in 2013, 1.8 in 2014, 3.1 in 2015, 6.2 in 2016, and 9.0 in 2017 (Figure 4). The rate increased on average by 8% per year from 1999 through 2013 and by 71% per year from 2013 through 2017.

"• The rate of drug overdose deaths involving heroin increased from 0.7 in 1999 to 1.0 in 2008 to 4.9 in 2016. The rate in 2017 was the same as in 2016 (4.9).

According to the Centers for Disease Control, using data available for analysis on September 5, 2018, there were a reported 70,652 deaths attributed to drug overdose in the US for the year ending December 2017. Some deaths were still under investigation. The CDC projects that the total for 2017 will be 72,222.

"We contribute nationally representative evidence to help answer each of these questions, including wholesale pricing data from a proprietary drug sales database spanning January 2006 to February 2017. We find that all formulations of naloxone increased in price since 2006 except for Narcan Nasal Spray. These cumulative increases totaled 2281% for the 0.4 MG single-dose products, 244% for the 2 MG single-dose products, 3797% for the 4 MG multi-dose products, and 469% for the 0.4 MG Evzio auto-injector.

"The US Drug Enforcement Administration introduced a schedule change for hydrocodone combination products in October 2014. During the period of our study, October 2013 to July 2016, the percentage of total drug sales represented by prescription opioids in the US doubled from 6.7% to 13.7%, which corresponds to a yearly increase of 4 percentage points in market share. It is not possible to determine the location of buyers from cryptomarket data. We cannot know, for example, if a drug shipped from a vendor in Europe was purchased by a US customer.

"Vulnerability to Opioid Overdose

"Of the 1,000,453 opioid recipients (81.7%) with at least 6 months of follow-up, 51.1% were female, and the median age was 17 years (interquartile range, 16-18 years). Among these adolescents, the estimated cumulative incidence of LTOT [Long Term Opioid Therapy] after first opioid receipt was 1.1 (95% CI, 1.1-1.2) per 1000 recipients within 1 year, 3.0 (95% CI, 2.8-3.1) per 1000 recipients within 3 years, 8.2 (95% CI, 7.8-8.6) per 1000 recipients within 6 years, and 16.1 (95% CI, 14.2-18.0) per 1000 recipients within 10 years.

"In this nationwide study of commercially insured adolescents, LTOT [Long Term Opioid Therapy] was relatively uncommon. The estimated incidence of LTOT receipt was 3.0 per 1000 adolescents within 3 years of filling an initial opioid prescription. Although adolescents with a wide range of preexisting mental health conditions and treatments were modestly more likely than adolescents without those conditions or treatments to receive an initial opioid, the former had substantially higher rates of subsequent transitioning to LTOT.