High rates of both incarceration and reduced household income are significantly associated with drug-related deaths in the United States, based a regression analysis of several decades of data.

“More than half a million drug-related deaths have occurred in the USA in the past three and half decades, however, no studies have investigated the association between these deaths and the expansion of the incarcerated population,” wrote Elias Nosrati, PhD, of the University of Oxford (England) and colleagues.

The researchers reviewed previously unavailable data on jail and prison incarceration at the county level from the nonprofit Vera Institute of Justice in New York, as well as mortality data from the U.S. National Vital Statistics System. The analysis was published in the Lancet Public Health.

After adjustment for multiple confounding variables, each standard deviation in admission rates to local jails (an average of 7,018 per 100,000 population) was associated with a significant 1.5% increase in drug-related deaths, and each standard deviation in admission rates to state prisons (an average of 254.6 per 100,000 population) was associated with a significant 2.6% increase in drug-related deaths, reported Dr. Nosrati and colleagues.

“On average, high incarceration rates correspond to 1.9 excess deaths per 100,000 county residents, corresponding to a treatment effect equal to a 53.5% increase in the mortality rate from drug use disorders,” the researchers wrote. In addition, each standard-deviation decrease in median household income was associated with a 12.8% increase in drug-related deaths within counties.

The findings were limited by several factors, including the observational nature of the study, the potential skewing of results because of missing data from some counties, and the inability to examine support for individuals released from jail or prison, the researchers noted.

However, the results suggest that, “when coupled with economic hardship, the operations of the prison and jail systems constitute an upstream determinant of despair, whereby regular exposures to neighborhood violence, unstable social and family relationships, and psychosocial stress trigger destructive behaviours,” they wrote.

In an accompanying comment, James LePage, PhD, wrote that current laws regarding trespassing, loitering, and vagrancy “unfairly criminalize individuals of low economic status and homeless individuals” by increasing their likelihood of interaction with the legal system and thus increasing the incarceration rate in this population.

“Future studies should focus on racial and ethnic biases in arrests and sentencing, and the subsequent effect on drug-related mortality,” wrote Dr. LePage of the VA North Texas Health Care System in Dallas.

Neither the researchers in the main study nor Dr. LePage had financial conflicts to disclose.

SOURCE: Nosrati E et al. Lancet Public Health. 2019 Jul 3;4:e326-33.