Engagement with opioid maintenance treatment and reductions in crime: a longitudinal national cohort study.

AIMS: This study investigates changes in criminal involvement among patients in opioid maintenance treatment (OMT) over a 7-year period prior to, during and after treatment, particularly in relation to differences in treatment engagement.

DESIGN, SETTING AND PARTICIPANTS: Treatment data on all patients who started OMT in Norway between 1997 and 2003 (n = 3221) were cross-linked with national criminal records. The period of observation was divided into four phases; pre-treatment, in-treatment, between treatments and post-treatment.

FINDINGS: During OMT, rates of criminal convictions for the cohort were reduced to fewer than half of waiting-list levels [incidence rate (IR) 0.63 versus 1.57]. Patients in continuous treatment had the fewest convictions (IR 0.47) during treatment. The highest rates were found among patients out of treatment after several treatment episodes (IR 1.52). All groups had significantly fewer criminal convictions during treatment compared to before treatment. Staying in OMT for 2 years or more was associated with significantly reduced rates of convictions during treatment. Younger age and pre-treatment criminal convictions were associated with significantly (P < 0.001) more convictions during treatment. Those who left treatment, permanently or temporarily, relapsed into high levels of convictions outside treatment.

CONCLUSIONS: Criminal activity appears to be reduced in Norway during opiate maintenance treatment. Younger age and prior history of criminal activity are important risk factors for continued criminal activity during treatment.