From 2015-2019, polydrug involvement in overdose deaths in North Carolina (NC) increased, according to a new article published in Drug and Alcohol Dependence. 

Authors of this study include Kristin Shiue, MPH, Graduate Research Assistant at IPRC, along with Anna Austin, PhD and Rebecca Naumann, PhD, Core Faculty at IPRC. This research was conducted in collaboration with Scott Proescholdbell, MPH, and Mary E. Cox, MPH, from the NC Department of Health and Human Services Division of Public Health, and Michelle Aurelius, MD, the Chief Medical Examiner of NC.

“There is an added layer of detail that can be gleaned from the literal text on death certificates, and this is frequently overlooked in overdose research,” Shiue explained. “We wanted to demonstrate the value of this data in improving overdose surveillance efforts.”

The researchers used NC death certificate data from 2015 and 2019 and leveraged the literal text, which is the descriptive information provided by the medical certifier of the death certificate, to analyze specific drug involvement in drug overdose deaths. Typically, research studying drug involvement in overdose fatalities uses standardized codes (known as ICD-10 codes). However, the use of ICD-10 codes alone results in an inability to understand more detailed and specific drug involvement, as the codes generally reflect broad categorizations of substances. Additionally, they can mask an understanding of the number of different drugs involved in a death from a research and surveillance perspective, if more than one drug is classified under the same broad category or class.

After systematically searching the literal text for drug mentions, the research team found that approximately 3 in 4 overdose deaths had polydrug involvement in NC from 2015-2019.  Literal text identified a greater percentage of deaths with polydrug involvement compared to ICD-10 codes alone. The substance classes most commonly involved in overdose deaths were opioids (80%), psychostimulants (37%), benzodiazepines (27%), alcohol (15%), and antiepileptics/ sedative-hypnotics (15%).

Rankings by year of the top 10 drugs involved in 2015–2019 overdose deaths and the top 10 drugs as a percentage of overdose deaths for 2015 and 2019

Through analysis of the literal text, the team was able to further identify the specific drugs driving the broader substance class trends. Over this period, opioid involvement in overdose deaths shifted from heroin and prescription opioids (e.g., oxycodone, hydrocodone) to predominantly fentanyl, the latter of which was involved in nearly 60% of overdose deaths in 2019. Psychostimulant involvement increased for both cocaine (2015: 21%, 2019: 35%) and methamphetamine (2015: 3%, 2019: 13%), and in 2019, nearly 80% of all overdose deaths involved a combination of fentanyl, cocaine, heroin, and/or methamphetamine.

“This study highlights the rapidly changing nature of the overdose crisis in North Carolina,” said Dr. Aurelius, “and we know that preventing these deaths will continue to take an all-hands approach between surveillance partners, researchers, public health professionals, clinicians and treatment providers, harm reduction colleagues, and advocates across the state.”

“We also wanted to develop an accessible resource, with the hope that other researchers and state partners will use and build upon our work,” said Shiue. The researchers have shared their code for searching the literal text here: To continue research in this area, the team is currently conducting a deeper investigation into overdose deaths by intent, including examining differences in specific drug involvement between unintentional versus suicide overdose deaths. To learn more, read the full article here: