Substance use linked with increased mortality in individuals released from prison

1. Substance use was significantly associated with increased all-cause mortality in individuals followed after release from prison, while psychiatric disorders were not found to be an independent risk factor.

2. A third of all deaths in men and half of all deaths in women were potentially attributable to substance use, with a large proportion of these deaths from external causes, such as accidents and suicides.

Evidence Rating Level: 2 (Good)           

Study Rundown: Individuals who have been released from prison have a higher mortality rate than the general population, but there is little evidence that identifies potential risk factors. The investigators in this large, longitudinal cohort study of ex-prisoners aimed to find specific risk factors associated with high mortality rates, such as substance use and psychiatric disorders. They also examined the effects of risk factors on both all-cause and external-cause (suicides, accidents, homicides) mortality, and whether any risk factors could predict external cause mortality.

Substance abuse, including alcohol and drug use, was found to be a significant risk factor for all-cause mortality, while psychiatric disorders were not found to be a risk factor. Additionally, a third of all deaths in men and half of all deaths in women were attributable to substance use, with a large proportion due to external causes (42% of men and 70% of women). This study was strengthened by the large sample size including all individuals released from prison in Sweden during the study period, and by accounting for potentially confounding variables. This study was limited by relying on data from registers for accurate reporting of psychiatric diagnoses, and also did not account for potentially reduced death rates in individuals who received treatment for substance use.

Click to read the study in The Lancet

Relevant Reading: All-cause and external mortality in released prisoners: systematic review and meta-analysis

In-Depth [prospective cohort]: This study followed 47,362 Swedish ex-prisoners, released between 2000 and 2009, until they died, emigrated from Sweden, or until the end of the study period (December 31, 2009). Data including information about substance use disorders, psychiatric disorders, criminological background, and demographics were obtained from large population registers. The primary outcome was death after release from prison during the follow-up period.

2,874 (6%) deaths occurred after release from prison during the median follow-up period of 5.1 years, with a median time from release to death of 3.5 years, resulting in an all-cause mortality rate of 1,205 deaths per 100,000 person years. 1,276 (44%) deaths were attributed to external causes, including non-traffic accidents and suicides. Other major causes of deaths included cancer and cardiovascular disease. Substance use was found to be a significant risk factor for all-cause mortality (alcohol use: adjusted Hazard Ratio [HR] 1.62, 95% CI 1.48–1.77; drug use: 1.67, 1.53–1.83). Substance use disorders were potentially attributable to 34% and 50% of all-cause deaths in men and women, respectively. Psychiatric disorders were not found to be an independent risk factor for mortality. In order to control for cofounding variables, the former prisoners were compared to siblings (also ex-prisoners) who were not found to have any substance use or psychiatric diagnoses, with no changes in all-cause mortality rate.

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