["Criminal Behaviour and Mental Health, Volume 31, Issue 3, Page 171-182, June 2021. ", "\nAbstract\n\nBackground\nDiscontinuation of substance use inpatient treatment is common, generally due to dropout and rule breaking. In turn, this is associated with worse long‐term substance use outcomes.\n\n\nAim\nTo investigate whether people who discontinued voluntary inpatient substance use treatment have a higher risk of imprisonment for a crime within 5 years of discontinuance than those who completed treatment.\n\n\nMethods\nThis registry‐based follow‐up study focused on all inpatient treatment episodes between 2002 and 2009 (N = 2893) in a Finnish hospital for treating addictions. Data from national registers on criminality, hospitalisations and education were linked. Cox regression analysis was used.\n\n\nResults\nDiscontinued treatment episodes were 1.4 times more likely to be followed by criminality leading to imprisonment during the 5‐year follow‐up period compared with completed treatment periods, after adjusting for age, gender, education, substance use diagnoses, earlier mental health disorders and prior imprisonments.\n\n\nConclusions\nOur findings strengthen the argument for ensuring completion of substance use treatment episodes; better completion rates could decrease the harm caused by serious criminality. Indeed, we recommend that crime reduction should be included to the long‐term goals of substance use treatment.\n\n"]