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The Norwegian Prison Release Study - nPRIS

The nPRIS cohort is based on data from the Norwegian Prison registry and includes all persons who have been imprisoned in Norway. The cohort has been updated several times (in 2015, 2018 and 2020), and has been linked to various national registers.


The last update includes all prisoners who have been imprisoned in Norway in the period 2000-2019 and includes about 160,000 people and just under 300,000 releases. This makes nPRIS one of the largest prison cohorts in the world and it is now linked to several national registers: the Norwegian Patient Register, the Cause of Death Register, the Criminal Case Register and socio-economic data from Statistics Norway. The nPRIS cohort thus provides unique opportunities to study how people are doing in prison, both before, during and after imprisonment. 

The nPRIS cohort is a central part of the PriSUD project, as similar cohort data is collected by our partners in Denmark and Sweden. The use of register data is often described as a «Nordic opportunity» and the Nordic countries are in an ideal position to conduct world-class quality research on drug-related public health challenges. 

Previous updates of the nPRIS cohort have formed the basis for a number of studies and collaborations, among others an article about overdose deaths after release from prison, which was published in 2017. The article received a lot of attention, including profiles on Norwegian television shows Dagsrevyen and, and the results from the article form the knowledge base for the national measures to prevent overdoses after release from prison.


The Mortality After Release from Incarceration Consortium (MARIC) study is a very ambitious and unique study that includes longitudinal data from 28 large studies in 13 countries, of which data from the nPRIS cohort are included. The goal of the study is to investigate deaths after release from prison. We have previously been involved in publishing a protocol article based on this collaboration and a new article with the first results is on the way.

In 2021, the second update of the nPRIS cohort formed the basis for a publication focusing on suicide among inmates in prison and after release. This article also received a lot of publicity when it was published, including on [Norwegian only]

In an article published in 2022, also on data from the second nPRIS cohort update, we found that release from a high level of security was associated with a higher risk of mortality. This study shows that people who were released from high-security prisons had a high mortality rate, both related to internal and external causes of death.

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