Uptake of Low-dose Buprenorphine Initiation and Associated Patient Characteristics in British Columbia, Canada: A Population-based Cohort Study.

Abstract

To characterize patterns of outpatient buprenorphine induction and examine factors associated with the use of low-dose initiation (LDI). A retrospective cohort study of 4510 adults initiating buprenorphine between January 1, 2016 and December 31, 2019 in British Columbia (BC), Canada, was undertaken using linked administrative data in the Provincial Overdose Cohort, which contains a 20% random sample of BC residents. Using multivariable modelling, we examined the association between sociodemographic, co-morbidity, treatment, and health service utilization variables, and the outcome of LDI. Joinpoint analysis was also conducted to assess inflection points in the prevalence of this practice. Overall, 7.2% of included buprenorphine inductions during the study period were classified as LDI. Joinpoint analysis revealed that the percentage of buprenorphine inductions classified as LDI increased significantly beginning in the fourth quarter of 2017. In multivariable analyses, factors positively associated with LDI included: older age (adjusted odds ratio [aOR]: 1.01, 95% CI: 1.00-1.02), living in Vancouver Coastal (aOR: 1.53, 95% CI: 1.13-2.06) and Fraser Health Authority regions (aOR: 2.56, 95% CI: 1.89-3.48) (vs interior region); having been prescribed slow-release oral morphine for opioid use disorder in the last 3 years (aOR: 4.03, 95% CI: 2.51-6.49), and having 1 (aOR: 2.40, 95% CI: 1.80-3.20) or ≥2 (vs 0) opioid agonist treatment episodes in the last 5 years (aOR: 2.56, 95% CI: 1.89-3.48). Factors negatively associated with microinduction included: male sex (aOR: 0.50, 95% CI:0.41-0.61), alcohol use disorder (aOR: 0.62, 95% CI: 0.40-0.96), injection drug use (aOR: 0.75, 95% CI: 0.61-0.94) and past-year incarceration (aOR: 0.19, 95% CI: 0.10-0.33). The use of LDI has increased in BC in recent years. Markers of treatment experience were positively associated with receipt of LDI. A ssessment of outcomes associated with LDI is needed.