Changes in substance use during outpatient treatment for substance use disorders: a prospective Norwegian cohort study from 2016 to 2020.

The present study demonstrates that inpatient detoxification was not associated with substance use changes over time for patients undergoing outpatient SUD treatment. Otherwise, injecting substance use was a particular risk factor for a high level of substance use. Future research needs to evaluate the impact of other treatment approaches on substance use, ideally in randomized controlled trials.