Initiation of buprenorphine in the emergency department or emergency out-of-hospital setting: A mixed-methods systematic review

Introduction: People who use substances increasingly access healthcare primarily through emergency medical services (EMS) and emergency departments (EDs). To meet the needs of these patients, EMS and EDs have become access points for medications for opioid use disorder (OUD), specifically buprenorphine. This systematic review aimed to quantify the efficacy of these programs, examining retention in treatment for OUD, rates of re-presentation to ED or EMS, and rates of precipitated withdrawal, as well as summarise clinician and patient perspectives on buprenorphine initiation in these settings. Methods: This review considered studies including patients with OUD receiving, and providers initiating, buprenorphine in an ED or EMS setting. A convergent, segregated approach to mixed-methods review was used as recommended by the Joanna Briggs Institute. A search was conducted of MEDLINE, CINAHL, EMBASE, and the Cochrane Library. Where relevant, meta-analyses of odds ratios and proportions were conducted. Findings: In both randomised (OR 5.97, 95 %CI 2.52–14.14, 227 participants, I² 16.93 %) and observational (OR 4.28, 95 %CI 2.45–7.48, 779 participants, I² 66.97 %) research, buprenorphine in the ED or EMS setting was associated with increased odds of treatment engagement at 30 days. Rates of retention in treatment varied across measured time points, from 77 % (95 %CI 74–80 %, 763 participants, I² 0.01 %) within 24 h, to 35 % (95 %CI 29–40 %) at 12 months. A low rate of precipitated withdrawal was reported (0.00 %, 95 %CI 0.00–1.00 %, 851 participants, I² 0.00 %). Clinicians and patients were generally supportive of ED-initiated buprenorphine, while identifying the initiation buprenorphine as one component of a longitudinal care path for people with OUD. Patients valued clinicians engaging in shared decision-making, while clinicians identified the environment of the ED often made this challenging. Conclusion: The initiation of buprenorphine in the ED setting is associated with higher odds of short and medium-term treatment engagement. Further research is required into EMS-initiated buprenorphine, as well as patient perspectives of ED- and EMS-initiated buprenorphine.