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. 2024 Sep 27:39:100898.
doi: 10.1016/j.lana.2024.100898. eCollection 2024 Nov.

Temporal and spatial trends of fentanyl co-occurrence in the illicit drug supply in the United States: a serial cross-sectional analysis

Tse Yang Lim  1 , Huiru Dong  2 , Erin Stringfellow  2 , Zeynep Hasgul  2 , Ju Park  3 , Lukas Glos  4 , Reza Kazemi  4 , Mohammad S Jalali  2
Affiliations

Temporal and spatial trends of fentanyl co-occurrence in the illicit drug supply in the United States: a serial cross-sectional analysis

Tse Yang Lim et al. Lancet Reg Health Am. .

Abstract

Background: Fentanyl and its analogs contribute substantially to drug overdose deaths in the United States. There is concern that people using drugs are being unknowingly exposed to fentanyl, increasing their risk of overdose death. This study examines temporal trends and spatial variations in the co-occurrence of fentanyl with other seized drugs.

Methods: We identified fentanyl co-occurrence (the proportion of samples of non-fentanyl substances that also contain fentanyl) among 9 substances or substance classes of interest: methamphetamine, cannabis, cocaine, heroin, club drugs, hallucinogens, and prescription opioids, stimulants, and benzodiazepines. We used serial cross-sectional data on drug reports across 50 states and the District of Columbia from the National Forensic Laboratory Information System, the largest available database on the U.S. illicit drug supply, from January 2013 to December 2023.

Findings: We analyzed data from 11,940,207 samples. Fentanyl co-occurrence with all examined substances increased monotonically over time (Mann-Kendall p < 0.0001). Nationally, fentanyl co-occurrence was highest among heroin samples (approx. 50%), but relatively low among methamphetamine (≤1%), cocaine (≤4%), and other drug samples. However, co-occurrence rates have grown to over 10% for cocaine and methamphetamine in several Northeast states in 2017-2023.

Interpretation: Fentanyl co-occurs most commonly with heroin, but its presence in stimulant supplies is increasing in some areas, where it may pose a disproportionately high risk of overdose.

Funding: This work was partly supported by FDA grant U01FD00745501. This article reflects the views of the authors and does not represent the views or policies of the FDA or US Department of Health and Human Services.

Keywords: Fentanyl co-occurrence; Illicit drug supply; Substance use; Temporal and spatial trends.

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Conflict of interest statement

TYL previously received an ORISE Fellowship from FDA, and has received consulting fees from the Massachusetts General Hospital Institute for Technology Assessment. JP has received consulting fees from FDA, and is a member of the Editorial Board of the International Journal of Drug Policy. LG and RK are employees of FDA. This article reflects the views of the authors and should not be construed to represent the views or policies of the FDA or the US Department of Health and Human Services. The authors declare no further conflicts of interest.

Figures

Fig. 1
Fig. 1
National trends in the proportionof different substance samples with co-occurring fentanyl in the United States, 2013–2023, showing monthly (dots and faint lines) and 12-month centered moving average monthly proportions (thick lines). Note the differing y-axis scales.
Fig. 2
Fig. 2
State-level annual totals of samples analyzed and reported, and trends in the proportion of fentanyl co-occurrence in the United States, 2013–2023. Data points for % of fentanyl among total samples in VT (year 2021: 51.1%; year 2023: 56.6%) and DE (year 2023: 51.1%) were excluded from the figure.
Fig. 3
Fig. 3
State-level trends in the yearly proportion of heroin samples with co-occurring fentanyl in the United States, 2013–2023. The following data points were excluded from the figure as the number of total tested samples was ≤5, which caused unstable estimates. For heroin: DE (year: 2021), ME (year: 2023), and SD (2023).
Fig. 4
Fig. 4
State-level trends in the yearly proportion of cocaine and methamphetamine samples with co-occurring fentanyl in the United States, 2013–2023. Data for cocaine for VT (2023) was excluded from the figure as the number of total tested samples was ≤5, which caused unstable estimates.
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