Using Precision Epidemiology to Identify Racialized Disparities in Overdose Mortality

Efforts to understand and respond to the opioid crisis have focused on overdose fatalities. Overdose mortality rates (ratios of overdoses resulting in death) are rarely examined though they are important indicators of harm reduction effectiveness. Factors that vary across urban communities likely determine which community members are receiving the resources needed to reduce fatal overdose risk. Identifying communities with higher risk for overdose mortality and understanding influential factors is critical for guiding responses and saving lives. Using incident reports and mortality data from 2018-2021 we defined overdose mortality ratios across Milwaukee at the census tract level. To identify neighborhoods displaying higher mortality than predicted, we used Integrated Nested Laplace Approximation to define standardized mortality ratios (SMRs) for each tract. Geospatial and spatiotemporal analyses were used to identify emerging hotspots for high mortality risk. Overall, mortality was highest in Hispanic and lowest in White communities. Communities with unfavorable SMRs were predominantly Black or Hispanic, younger, less employed, poorer, less educated, and had higher incarceration rates and worse mental and physical health. Communities identified as hotspots for overdoses were predominantly non-White, poorer, and less employed and educated with worse mental and physical health, higher incarceration rates, and less housing stability. The findings demonstrate that overdose mortality rates vary across urban communities and are influenced by racial disparities. A framework that enables identification of challenged communities and guides community responses is needed.