BACKGROUND AND AIMS: An investigation of 24 weeks of extended-release buprenorphine (BUP-XR; Sublocade®) treatment for adults with opioid use disorder (OUD). Study aims were to characterise variations in clinical response, investigate personal factors influencing BUP-XR experience and identify opportunities to tailor treatment interventions.

DESIGN: A convergent parallel mixed-methods evaluation embedded in a five-centre, phase 3, randomised controlled trial of BUP-XR versus daily oral methadone or sublingual buprenorphine.

SETTING: Four of five National Health Service addictions treatment clinics in England and Scotland from the trial.

PARTICIPANTS: Participants were recruited after they completed the 24-week endpoint. Forty-nine participants (31%) from the trial completed the qualitative interview.

MEASUREMENTS: Three outcome measures from the trial's dataset were used descriptively: (1) fortnightly clinic visit administered TimeLine Follow-Back interview and urine drug screen data on use of non-medical opioids, cocaine and benzodiazepines; (2) the frequency version of the 11-item Craving Experience Questionnaire administered at baseline and endpoint; and (3) the Structured Clinical Interview for DSM-5 disorders for diagnosis of early OUD and cocaine use disorder (CUD) remission. Data visualisation (by heatmap) identified drug use response sub-groups. A topic-guided, semi-structured qualitative interview was analysed by Interactive Categorisation.

FINDINGS: Three response sub-groups were identified: Group 1 [14 (28.5%) of 49 participants] had the highest level of response, characterised by continuous abstinence from opioids, cocaine and benzodiazepines, improvements in craving control and mental and physical health in the majority, and a high level of remission and satisfaction with care; Group 2 [14 (28.5%) of 49 participants] had the next level of response, characterised by continuous abstinence from opioids, but some with opioid craving and some with compensatory use of cocaine and benzodiazepine to cope with anxiety and stress; Group 3 [21 (43.0%) of 49 participants] were not continuously abstinent from opioids during follow-up, the majority had dual OUD and CUD at trial enrolment, some reported breakthrough opioid withdrawal symptoms during follow-up, the majority reported improvements in mental health, but many reported opioid and cocaine cravings and compensatory use of cocaine and benzodiazepines.

CONCLUSIONS: There appears to be variation in response and experience of extended-release buprenorphine during the first six months of treatment, depending on substance use and physical health. This highlights the need for tailored treatment plans based on differing individual needs.