"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.

"Of the 36,667 drug overdose deaths with at least one mention of a specific drug, 52% mentioned only one specific drug (18,931 deaths), 26% mentioned two (9,351 deaths), 12% mentioned three (4,521 deaths), 6% mentioned four (2,041 deaths), and 5% mentioned five or more (1,823 deaths). Among drug overdose deaths with at least one mention of a specific drug, the average number of specific drugs mentioned was 1.9.