Senior Scientist UNC Injury Prevention Research Center, University of North Carolina, Chapel Hill, NC, USA Chapel Hill, United States
Background: Death certificates are the main source of drug overdose mortality in the US. The literal text on death certificates can support analysis at the level of active pharmaceutical ingredients involved in overdose deaths. Distinguishing cases where a single substance was involved from polysubstance cases is important for informing policy and regulatory decisions but can be challenging.
Objectives: To explore the utility of the drug mention with involvement (DMI) methodology, developed collaboratively by the U.S. Food and Drug Administration and the National Center for Health Statistics, to be used for classifying drug overdose deaths as single- vs polysubstance- drug overdose deaths.
Methods: This study used death certificates and postmortem toxicology results for Kentucky residents who died from drug overdose in 2021. Postmortem toxicology in Kentucky is mandated and centralized. The DMI methodology used contextual analysis of the literal text on each death certificate, identified drug search terms (drug names, metabolites, precursors, analogs, and misspellings) mentioned with involvement, and mapped them to referent (generic) drug groups. Deaths involving multiple referent drug groups were classified as polydrug deaths.
Results: Of the 2248 drug overdose deaths, 692 (31%) deaths implicated a single referent drug, 1395 (62%) were classified as polydrug, and 161 (7%) did not list specific drug involvement. Among the top 20 DMIs overall, the highest percentage of single drug deaths was estimated for methadone (37%), fentanyl (28%), methamphetamine (14%), and cocaine (10%). Specific benzodiazepines, including alprazolam, clonazepam, and diazepam were among the lowest percentage of single substance deaths ( < 5%), as were amphetamine, gabapentin, heroin, and morphine. The agreement between drugs detected by postmortem toxicology and listed as DMI was high for fentanyl (94%), methamphetamine (86%), methadone (73%), cocaine (72%) and oxycodone (71%). Agreement between toxicology and DMI was lower (~50%) for heroin, clonazepam, and gabapentin. Morphine, oxymorphone, and codeine were listed as DMI in less than one third of the cases with toxicology positive for these substances, which are also metabolites of other substances.
Conclusions: The variable, and sometimes low, agreement between DMI and postmortem toxicology results suggests that literal text analysis for DMI presents challenges in classifying a drug overdose death as a single- vs. polydrug overdose death. Perceptions of coroners and medical examiners as to the most dangerous drugs may lead to incomplete documentation, with potential omissions of contributing drugs and emerging threats.
