Millennium Health Signals Report^® Volume 8.1

Recent research suggests that a disruption of the illicit fentanyl supply may have contributed to the dramatic declines in fentanyl overdose deaths across the U.S. in 2023 and 2024. While that study primarily focused on the relationship between fentanyl purity levels and fentanyl overdose deaths, clinical urine drug testing data offer complementary information about changes in the prevalence of fentanyl detection and exposure levels (i.e., concentrations) as well as changes in the co-detection of other drugs (e.g., fentanyl, xylazine) with fentanyl that may provide additional insight into changes in the illicit opioid supply and/or patterns of use. Here we analyzed more than 976,000 clinical urine drug test results from patients across the U.S. with a substance use disorder diagnosis to compare recent changes in fentanyl use in the Western and Eastern U.S. and explore their potential implications for fentanyl overdose deaths in these areas of the country.

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