Comparing Outpatient Treatment Retention Among Individuals Using Fentanyl Randomized to Low-dose and Direct-to-inject Buprenorphine Initiation

Inclusion Criteria: * Age ≥ 18 years of age at Visit 1. * Documentation of an OUD diagnosis as evidenced by meeting two or more of the DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, 5th Edition) Criteria for Opioid Use Disorder * Self-reported daily use of fentanyl ≥ 5 out of the past 7 days at baseline, * Fentanyl-positive urine drug screening at baseline, * Interest in stopping or reducing fentanyl use, * Publicly insured through San Francisco Medicaid or Medicare and therefore able receive buprenorphine prescription dispensing through Community Behavioral Health Services (CBHS) Pharmacy Exclusion Criteria: * Currently nursing, pregnant, or anticipating pregnancy in the next 6 months * Methadone-positive urine drug screening at baseline * Buprenorphine-positive urine drug screening at baseline * Be unable to provide any locator or contact information at least one contact in addition to themselves * Any pending legal action that could prevent participation in study activities * Presence of a condition or abnormality that, in the opinion of the Investigator, would compromise the safety of the patient or the quality of the data (e.g., acute psychosis), or cognitive impairment (e.g., dementia)