Factors Associated with Retention in Opioid Agonist Treatment: A Mixed-Methods Approach

Background: The overall aim was to investigate factors associated with treatment retention and dropout in opioid antagonist treatment (OAT) through a mixed-methods approach.

Methods: This thesis consists of three studies; a systematic review to identify factors associated with retention/dropout in OAT according to the Maudsley Addiction Profile, followed by a six month prospective cohort study in a specialist treatment setting in Ireland exploring factors associated with dropout, and finally a qualitative study with service users and providers exploring barriers and facilitators to retention.

Results: The systematic review included 67 articles across 21 countries with varying definitions of retention/dropout. The median retention rate was 57% at 12-months (n=37) and 38.4% at three years (n=8). Older age and higher doses were associated with increased retention in the majority of studies. Studies investigating substance use, negative attitudes to MMT, criminal activity and arrests/incarceration found them to be associated with reduced retention. Of 117 participants in the cohort study, excluding five lost to follow-up, 5% (n=6) had dropped out at six-months. Analysis was limited given the sample size and dropout rate, however, IV drug use showed evidence of an association with dropout (p=0.027). In the qualitative study, with data collected from 14 service users and eight service providers, social support, self-motivation and familial incentives were identified as facilitators to retention. Furthermore, areas for improvement in order to facilitate retention included the therapeutic relationship, views of OAT and a disparity in goals set.

Conclusion: Overall, this thesis adds to the body of evidence investigating factors associated with retention in OAT among adults. Principal findings of the systematic review highlighted heterogeneity in the definition and measurement of retention, making it difficult to compare studies. Despite this, younger age, substance use, lower doses of methadone, criminal activity/incarceration, and negative attitudes to MMT appeared to be associated with reduced retention. The cohort study identified a high retention rate at six-months with evidence of an increase in IV drug use in those who dropped out. Finally, barriers to retention were identified, with some consensus between service users and providers regarding opportunities for improvement. Future research is required to develop a consensus on the definition of retention and further explore circumstances leading participants to dropout of OAT.