Addiction recovery among opioid-dependent patients treated with subcutaneous buprenorphine depot: an interim analysis

Background
The long-lasting effect of once-weekly or once-monthly injectable depot buprenorphine can have positive impacts on the quality of life (QOL) and social participation among patients in opioid agonist treatment (OAT) (Lintzeris et al. 2021). The ARIDE study aims to evaluate the effects of injectable depot buprenorphine treatment on the addiction rehabilitation of patients in OAT in Germany.
 
Methods
The ongoing study is a non-randomized prospective observational study with a comparison group (treatment-as-usual). The planned total sample size is N = 426. To ensure comparability between groups, suitable patients from the same OAT unit are matched pairwise to each patient treated with injectable depot buprenorphine. Matching criteria included sex, duration of OAT, take-home prescription, and psychosocial functioning. Primary study endpoint is the difference of change in QOL, assessed with the Opioid Substitution Treatment Quality of Life scale (OSTQOL), within the depot buprenorphine group between baseline and month 12. 
For secondary analyses, group comparisons will be made on changes in terms of QOL and further patient-reported outcomes. Satisfaction with medication is assessed by the Treatment Satisfaction Questionnaire for Medication (TSQM-14), frequency and intensity of craving as well as dosage adequacy are measured with the Opiate Dosage Adequacy Scale (ODAS). Analyses were carried out according to the per-protocol principle by comparing mean scores and using dependent t-tests. 
 
Results 
Out of 330 patients recruited to date, treatment data of 176 patients (depot group n = 86, comparison group n = 90) were included in an interim analysis. Within the depot group, 62 patients received depot buprenorphine for the entire study period of 12 months (“depot only”; 72.1%) and 24 patients started with depot buprenorphine but returned to oral buprenorphine within the study period (n = 24) (“converter”; 27.9%). 
The per-protocol analysis of the OSTQoL data (paired t-tests per group between baseline and month 12) shows improvements in QOL among “depot only” patients (n = 59) (Baseline: 2.52 (SD 0.65), Month 12: 2.78 (SD 0.64), p = .001), but also within the comparison (n = 88) (Baseline: 2.45 (SD 0.68), month 12: 2.58 (SD 0.65), p = .013) and the “converter” group (n=24) (Baseline: 2.70 (SD 0.77), Month 12: 2.85 (SD 0.67), n.s.). 
Satisfaction with medication increased among patients in the “depot only” group and the comparison group. Adequacy of dosage increased slightly among patients in the “depot only” group and significantly in the “converter” group.
 
Discussion
The preliminary results in this per-protocol sample indicate improvements in patient-reported outcomes among OAT patients treated with injectable depot buprenorphine, here in terms of QOL, global satisfaction with medication and adequacy of dosage. The results need to be confirmed in further analyses with a larger sample as well as intention-to-treat analyses and direct group comparisons.