Imprisonment, community sanctions and mortality by cause of death among patients with substance use disorder - a 28-year follow-up using Finnish register data.

Background: The first few weeks' post-imprisonment are associated with high mortality, particularly among individuals with a history of substance use. Excess risk may vary by societal context due to a range of penal systems and substance use patterns. Using data on Finnish individuals who had sought treatment for substance use, we studied the association between criminal sanctions with cause-specific mortality.

Methods: The database contained 10887 individuals who had sought treatment between 1990 and 2009. Their treatment data were combined with register data on imprisonments and community sanctions and weekly mortality between 1992 and 2015. Mortality was analysed using discrete-time survival models. We controlled for age and sociodemographic factors, and analysed whether education, type of substance used and the type of latest sentence modified the associations.

Findings: Mortality was high in the first two weeks after sanctions (all-cause odds ratio [OR] 2.61, 95% confidence interval [CI] 1.67-4.07; drug-related deaths OR 8.52, 95% CI 4.64-15.7). Excess risk declined over time (OR after 12 weeks: 1.19, 95% CI 1.07-1.31). Most of the excess risk was attributable to external causes. Mortality was low during imprisonment, but not during community sanctions. The patterns were similar by level of education, substance use and the type of latest sentence.

Conclusions: Community sanctions were not associated with mortality among people with substance use disorders. Mortality was low during imprisonment, but high post-release. Criminal sanctions should be better utilised as intervention touchpoints and follow-up resources should target prisoners with substance use treatment history to reduce post-release mortality.