Measuring Treatment Attrition at Various Stages of Engagement in Opioid Agonist Treatment in Ontario Canada Using a Cascade of Care Framework

Background: The cascade of care framework is an effective way to measure attrition at various stages of engagement in Opioid Agonist Treatment (OAT). The primary objective of the study was to describe the cascade of care for individuals who have accessed OAT from a network of specialized addiction clinics in Ontario, Canada. The secondary objectives were to evaluate correlates associated with retention in OAT at various stages and the impact of patients' location of the residence on retention in OAT. Design: A multi-clinic retrospective cohort study was conducted using electronic medical record (EMR) data from the largest network of OAT clinics in Canada (70 clinics) from 2014-2020. Study participants included all individuals who received OAT from the network of clinics during the study period. Measurements: In this study, four stages of the cascade of care framework were operationalized to identify treatment engagement patterns, including patients retained within 90 days, 90 to 365 days, one to two years, and more than two years. Correlates associated with OAT retention for 90 days, 90 to 365 days, one to two years, and more than two years were also evaluated and compared across rural and urban areas in northern and southern Ontario. Results A total of 32,487 individuals were included in the study. Compared to individuals who were retained in OAT for 90 days, individuals who were retained for 90 to 365 days, one to two years, or more than two years were more likely to have a higher number of treatment attempts, a higher number of average monthly urine drug screening and a lower proportion of positive urine drug screening results for other drug use. Conclusion Distinct sociodemographic and clinical factors are likely to influence treatment retention at various stages of engagement along the OAT continuum. Research is required to determine if tailored strategies specific to people at different stages of engagement have the potential to improve outcomes of OAT.