Drug use and re-imprisonment: A prospective study of the Norwegian Offender Mental Health and Addiction (NorMA) cohort

BACKGROUND: Re-imprisonments are common among people in prison who use drugs. This study aims to describe sociodemographic factors, mental health and level of pre-prison substance use in a cohort of people in prison, and to investigate re-imprisonment during follow-up according to their level of pre-prison drug use. METHODS: This was a prospective study using baseline data from the Norwegian Offender Mental Health and Addiction (NorMA) cohort (n = 733) recruited in 2013–2014 linked to data from the Norwegian Prison Registry and the Norwegian Cause of Death Registry. Self-reported drug use before imprisonment was measured at baseline using the Drug Use Disorder Identification Test (DUDIT). The outcome of interest was re-imprisonment examined using Cox regression. We excluded 32 persons because they were not released before the study ended. The study sample included 701 persons, with a total time-at-risk of 2479 person-years. RESULTS: Almost half of the study sample reported high-risk drug use before imprisonment (DUDIT score >24). During the study period, 43% (n = 267) were re-imprisoned. People with high-risk use had a hazard ratio (HR) of 4.20 (95% CI: 2.95–5.97) of re-imprisonment compared with people with low-risk use (DUDIT score <6). Older age and more education than primary school were associated with a reduced risk of re-imprisonment. CONCLUSION: Compared with low-risk use, high-risk drug use is highly prevalent among people in prison and is associated with higher rates of re-imprisonment. This highlights the need for screening and treatment of drug use disorders among people in prisons.