Individual- and Area-Level Incarceration and Mortality.

Importance: The US has the highest incarceration rates in the developed world. The harms of incarceration have long-term health implications, including increased mortality. Existing studies of incarceration-related mortality are limited by data sources and design. Objective: To examine the associations between both individual- and area-level incarceration rates with all-cause and overdose mortality in the US. Design, Setting, and Participants: This cohort study used data from the Mortality Disparities in American Communities (MDAC) study, linking over 3 million 2008 American Community Survey (ACS) respondents to National Death Index data from the respondents' 2008 interview date through December 31, 2019, or their date of death, and county incarceration data from the Vera Institute of Justice. The sample included US adults 18 years or older, representing individuals in group quarters such as prisons and jails but excluding those in counties lacking jail incarceration rate data. Data were analyzed from July 5, 2023, to November 10, 2024. Exposure: Individual incarceration status at the time of the ACS survey and county jail incarceration rates. Main Outcomes and Measures: The outcomes of interest were all-cause mortality and overdose mortality, assessed through time-to-event analyses. Cox proportional hazard models were used to estimate mortality risks, adjusting for individual- and county-level characteristics. ACS survey weights were applied so that the final sample represents the US adult population. Results: The study includes a total of 3 255 000 individuals (51.3% female), of whom 45 000 (0.93%) were incarcerated at the time of the 2008 ACS administration. The mean (SD) county jail incarceration rate was 372 (358) per 100 000 people. During the study period, 431 000 individuals (11.6%) died from any cause, and 5500 (0.2%) died from overdoses. Incarcerated individuals had a higher risk of all-cause mortality (hazard rate [HR], 1.39 [95% CI, 1.33-1.45]) and an increased risk of overdose mortality (HR, 3.08 [95% CI, 2.70-3.52]) compared with nonincarcerated individuals. A 10% increase in county jail incarceration rates was associated with 4.6 (95% CI, 3.8-5.5) additional all-cause deaths per 100 000 people. Conclusions and Relevance: In this cohort study of 3.26 million individuals in the US, results highlighted the dual burden of incarceration on health outcomes. Individuals who were incarcerated faced significantly higher risks of death, particularly from overdoses, and elevated county incarceration rates exacerbated individual-level mortality risks. These findings suggest the need for reforms in criminal justice and public health policies to address these elevated risks and their widespread implications.