Spatiotemporal clustering of state-level opioid, opioid-stimulant, and opioid-benzodiazepine polysubstance deaths across the U.S.: Hierarchical agglomerative clustering analysis.

Abstract

Polysubstance use continues to complicate the US overdose landscape, with over 107,000 lives lost to drug overdoses in 2022. The present study uses hierarchical agglomerative clustering to identify distinct spatiotemporal profiles of opioid-only, opioid-stimulant, and opioid-benzodiazepine overdose deaths. We used de-identified data sourced from the CDC's WONDER Multiple Cause of Death file, covering the period from 2004 to 2022. Hierarchical Agglomerative Clustering was used to classify and assign age-adjusted mortality rate (AAMR) trends for opioid-only, opioid-stimulant, and opioid-benzodiazepine combinations into distinctive clusters based on their temporal and spatial similarities using the dynamic time warping (DTW) metric. The opioid-only, opioid-stimulant, and opioid-benzodiazepine clusters each yielded four clusters. The Opioid-only clusters were characterized by states with AAMRs showing the following trajectory patterns of change over time: lower-level, gradual increase (n = 22 states, 43.14%), delayed acceleration (post-2015) (n = 10 states, 19.61%), early rapid increase (n = 18 states, 35.29%), and a higher-level, accelerating trajectory containing only West Virginia. The Opioid-Stimulant clusters were characterized by states with lower-level, gradual increase (n = 33 states, 64.71%), delayed acceleration (post-2015) (n = 9 states, 17.65%), early rapid increase (n = 8 states, 15.69%), and West Virginia, which had a higher-level, accelerating trajectory. The Opioid-Benzodiazepine clusters were characterized as low-level, minimal change (n = 27 states, 52.94%), steady increase (n = 18; 35.29%), early rapid increase with a recent decline (n = 5, 9.80%), and West Virginia, which was characterized as having a higher-level, irregular trajectory denoting substantial variability. These findings reveal significant spatial and temporal variation, with West Virginia consistently emerging as an outlier with the highest AAMR. These findings further underscore the need for region-specific interventions to curb the growing opioid crisis.