Stimulant use disorder diagnosis and opioid agonist treatment dispensation following release from prison: a cohort study

Background Concurrent opioid and stimulant use is on the rise in North America. This increasing trend of use has been observed in the general population, and among people released from prison in British Columbia (BC), who face an elevated risk of overdose post-release. Opioid agonist treatment is an effective treatment for opioid use disorder and reduces risk of overdose mortality. In the context of rising concurrent stimulant use among people with opioid use disorder, this study aims to investigate the impact of stimulant use disorder on opioid agonist treatment dispensation following release from prison in BC. Methods Linked health and corrections records were retrieved for releases between January 1(st) 2015 and December 29(th) 2018 (N = 13,380). Hospital and primary-care administrative health records were used to identify opioid and stimulant use disorder and mental illness. Age, sex, and health region were derived from BC's Client Roster. Incarceration data were retrieved from provincial prison records. Opioid agonist treatment data was retrieved from BC's provincial drug dispensation database. A generalized estimating equation produced estimates for the relationship of stimulant use disorder and opioid agonist treatment dispensation within two days post-release. Results Cases of release among people with an opioid use disorder were identified (N = 13,380). Approximately 25% (N = 3,328) of releases ended in opioid agonist treatment dispensation within two days post-release. A statistically significant interaction of stimulant use disorder and mental illness was identified. Stratified odds ratios (ORs) found that in the presence of mental illness, stimulant use disorder was associated with lower odds of obtaining OAT [(OR) = 0.73, 95% confidence interval (CI) = 0.64-0.84)] while in the absence of mental illness, this relationship did not hold [OR = 0.89, 95% CI = 0.70-1.13]. Conclusions People with mental illness and stimulant use disorder diagnoses have a lower odds of being dispensed agonist treatment post-release compared to people with mental illness alone. There is a critical need to scale up and adapt opioid agonist treatment and ancillary harm reduction, and treatment services to reach people released from prison who have concurrent stimulant use disorder and mental illness diagnoses.