Fentanyl shock: The changing geography of overdose in the United States

Background: Rapid increases in drug overdose deaths in the United States since 2014 have been highly regionally stratified, with the largest increases occurring in the eastern and northeastern states. By contrast, many western states saw overdose deaths plateau. This paper shows how the differential influx of fentanyl and fentanyl analogues in the drug supply has reshaped the geography and demography of the overdose crisis in the United States. Methods: Using all state lab drug seizures obtained by Freedom of Information Act request, I analyze the regionally distinctive presence of fentanyl in the US drug supply with descriptive plots and statistical models. Main analyses explore state-year overdose trends using two-way fixed effects ordinary least squares (OLS) regression and two-stage least squares regression (2SLS) instrumenting for fentanyl exposure with state-longitude times a linear trend. Results: First, fentanyl exposure is highly correlated with geography and only weakly explained by overdose rates prior to 2014. States in the east (higher degrees longitude) are much more heavily affected. Second, fentanyl exposure exhibits a statistically significant and important effect on overdose mortality, with model-predicted deaths broadly consistent with official death statistics. Third, fentanyl exposure explains most of the variation in increased overdose mortality between 2011 and 2017. Consequently, the epicenter of the overdose crisis shifted towards the eastern United States over these years. Conclusion: These findings shed light on the "third-wave" of the overdose epidemic, characterized by rapid and geographically disparate changes in drug supply that heighten the risk of overdose. Above all, they underscore the urgency of adopting evidence-based policies to combat addiction in light of the rapidly changing drug environment.