Summary

Background Drug use disorders are an increasing cause of disability and early death in the USA, with substantial geographical variation. We aimed to investigate the associations between economic decline, incarceration rates, and age-standardised mortality from drug use disorders at the county level in the USA.

Methods In this observational analysis, we examined age-standardised mortality data from the US National Vital Statistics System and the Institute for Health Metrics and Evaluation, household income data from the US Census Bureau, and county-level jail and prison incarceration data from the Vera Institute of Justice for 2640 US counties between 1983 and 2014. We also extracted data on county-level control variables from the US Census Bureau, the National Center for Health Statistics, and the US Centers for Disease Control and Prevention. We used a two-way fixed-effects panel regression to examine the association between reduced household income, incarceration, and mortality from drug use disorders within counties over time. To assess between-county variation, we used coarsened exact matching and a simulation-based modelling approach.

Findings After adjusting for key confounders, each 1 SD decrease in median household income was associated with an increase of 12·8% (95% CI 11·0–14·6; p<0·0001) in drug-related deaths within counties. Each 1 SD increase in jail and prison incarceration rates was associated with an increase of 1·5% (95% CI 1·0–2·0; p<0·0001) and 2·6% (2·1–3·1; p<0·0001) in drug-related mortality, respectively. The association between drug-related mortality and income and incarceration persisted after controlling for local opioid prescription rates. Our model accounts for a large proportion of within-county variation in mortality from drug use disorders (R2=0·975). Between counties, high rates of incarceration were associated with a more than 50% increase in drug-related deaths.

Interpretation Reduced household income and high incarceration rates are associated with poor health. The rapid expansion of the prison and jail population in the USA over the past four decades might have contributed to the increasing number of deaths from drug use disorders.