Examining the association between county racialised economic segregation and fatal overdose in US counties, 2018-2022

Between 2022 and 2023, overdose mortality decreased among non-Hispanic (NH) white people but stayed the same or increased among people of colour in the USA. County racialised economic segregation may contribute to overdose mortality.

We used a Bayesian spatiotemporal approach to assess the association between racialised economic segregation quintile and overdose deaths (overall and race-stratified) in 3133 US counties from 2018 to 2022. Segregation was measured using the Index of Concentration at the Extremes for race/ethnicity and income (ICE_race-income). We included two ICE_race-income measures, one for higher-income NH white and lower-income black residents and another for higher-income NH white and lower-income Hispanic residents. Models included random effects for county, year and county-year interaction, and fixed effects for proportion male, proportion aged 25-44, land area, state and year. We estimated relative risk (RR) by quintile (least vs most privileged) and the difference in overdose mortality per 100 000 (RD) had all counties shifted to the risk of the most advantaged counties (Q5).

Counties with the highest proportion of lower-income racially minoritised residents (Q1) had an increased RR of overdose deaths compared with Q5 counties, both overall (aRRs 1.64 (1.51-1.78); 1.40 (1.29-1.52)), and among subgroups. Had all counties experienced the risk of Q5 counties, we estimated an average reduction in overdose deaths overall (RDs per 100 000: -7.20 (-8.25 to -6.10); -6.37 (-7.38 to -5.25)) and among subgroups.

County racialised economic segregation was associated with overdose mortality risk in 2018-2022. Investment in evidence-based strategies to reduce overdose risk in places experiencing harms related to racialised economic segregation is critical.