The main purpose of this stepped wedge trial will be to test the impact of a bundle of implementation strategies designed to improve ED-outpatient care coordination on long-term buprenorphine retention among adult patients who start buprenorphine for opioid use disorder in a hospital emergency department (ED) and then are referred for continued outpatient buprenorphine treatment after they leave the ED. Our hypothesis is that adopting the bundle of implementation strategies will be associated with subsequent increases in:

A) Cumulative number of days with active buprenorphine prescription at 3, 6, and 12 months after patients' initial ED visit (6 months = primary outcome)

B) Proportion of patients with active buprenorphine prescriptions without gaps in buprenorphine coverage of more than 7 days at 3, 6, and 12 months after patients' initial ED visit

C) Proportion of patients who fill at least 1 outpatient buprenorphine prescription within 30 days of their ED visit

D) Clinician reported quality of ED-outpatient care coordination and care transitions

Buprenorphine is a highly effective but underused medication for opioid use disorder that reduces cravings and decreases overdose risk. Starting buprenorphine for opioid use disorder in emergency departments (EDs) is recognized as a best clinical practice in the US. However, effective strategies to help patients sustain buprenorphine treatment after they leave the ED are urgently needed. To increase access to buprenorphine treatment, California established California Bridge, a state-funded program that offers same-day buprenorphine initiation plus referral to outpatient opioid use disorder treatment for patients. However, suboptimal ED-outpatient care coordination is a common barrier to buprenorphine retention. During a prior study, we identified a bundle of implementation strategies designed to improve ED-outpatient care coordination for patients who start buprenorphine for opioid use disorder in the ED. In this hybrid effectiveness-implementation study, the research team will work with core clinical teams at 12 sites (4 EDs and 8 outpatient clinics [2 clinics per ED]) to implement a bundle of implementation strategies at each site. Implementation will occur over a 12 month period (~3 months per site). Patient cohorts will be identified through electronic health record query reports. Data from eligible patients will then be abstracted from the electronic health record at each hospital. Changes in care coordination will be assessed using clinician surveys. Treatment outcomes will be assessed using buprenorphine prescription records obtained from California's prescription drug monitoring program linked to electronic health record data at the patient level. Study results will be used to develop an implementation blueprint that hospitals in California and across the US can use to improve opioid use disorder treatment outcomes for patients who start buprenorphine in hospital EDs.

Inclusion Criteria:

• patients who start buprenorphine for opioid use disorder at a participating ED

De-identified IPD will be deposited in a public data registry as required by NIH HEAL data sharing guideilnes. However, due to state-level restrictions, individual level buprenorphine prescription data will not be shared.

expected 12 months after study completion