For the analysis of polysubstance use and its association with MOUD initiation, the primary outcome was OUD treatment type, operationalized as mutually exclusive categories of medication type (ie, buprenorphine, oral naltrexone, or ER naltrexone) or psychosocial treatment without MOUD (reference group). The exposure variable was presence of a cooccurring SUD in the 6-month preceding treatment, spanning alcohol, stimulant (cocaine and/or amphetamines), and/or sedative use disorder, as well as individuals without recent SUD diagnoses.
