Introduction- This research evaluates whether the January, 2021 decriminalization of drug possession in Oregon was associated with changes in fatal drug overdose rates after accounting for the timing and spread of fentanyl through Oregon’s unregulated drug market, a substance known to drive fatal overdose rates.
Methods- The association between fatal drug overdose and enactment of M110 in Oregon was analyzed using a matrix completion synthetic control method imputed from 48 US states and Washington DC. The rapid escalation of fentanyl in unregulated drug markets was determined using the state-level percentage of all samples reported to the National Forensic Laboratory Information System that were identified as fentanyl or its analogs. A changepoint analysis was used to determine when each state experienced a rapid escalation of fentanyl in its unregulated drug market. Mortality data were obtained from the Centers for Disease Control and Prevention from 2008-2022.
Results- Analysis indicated a rapid escalation of fentanyl in Oregon’s unregulated drug supply occurred in the first half of 2021, contemporaneous with the enactment of M110. The crude association between decriminalization and fatal overdose rate per 100,000 per half-year was significant (Tau = 1.83; SE = 0.39; p < 0.001); however, adjusting for the rapid escalation of fentanyl as a confounder, the effect of drug decriminalization on overdose mortality in Oregon was null (Tau = -0.51; SE = 0.36).
Conclusions- Future evaluations of drug policies should account for confounding changes in the composition and potency of unregulated drug markets.