Receipt of ED-initiated/expedited BUP will be operationally defined to include the provision of a specific "warm" referral or transfer of care to a provider, clinic, or treatment setting with the capacity to administer and/or prescribe BUP within 24 hours of completion of the ED/EDOU visit. Eligible transition of care will be will described further in the Manual of Operations (MOP) and will include direct transport or handoff to an outpatient provider immediately from the ED, provision of an appointment within 24 hours (with a specific time and location), transfer to general inpatient or inpatient OUD/addiction treatment. Neither confirmation of a completed appointment (i.e., patient shows up and is seen) nor receipt of BUP at the dedicated follow-up appointment will be required as the patient and treating provider may elect to treat with alternative regimes (e.g., methadone, naltrexone). This measure will be abstracted from the health record primarily.