This is an observational, "ancillary study" intended to describe opioid use among opioid use disorder patients following their discharge into the community from inpatient detoxification and/or short-term residential treatment programs affiliated with parent study CTN-0051, which assessed the comparative effectiveness of extended release injectable naltrexone (XR-NTX, Vivitrol®), an opioid antagonist recently approved and indicated for the prevention of relapse to opioid dependence, versus buprenorphine-naloxone (BUP-NX, Suboxone®), a high affinity partial agonist indicated for maintenance treatment of opioid dependence, as pharmacotherapeutic aids to recovery.

Participant recruitment will begin after recruitment for CTN-0051 has been completed. Opioid use disorder patients will be recruited prior to leaving detoxification and/or short-term residential programs. Screening and baseline data (focused on demographics, diagnosis and service utilization) will be collected prior to discharge, and follow-up data (focused on opioid use) will be collected at weeks 1, 4 and 8 following discharge.

Inclusion Criteria:

• 18 years or older;
• Meet DSM-5 criteria for opioid-use disorder (heroin or prescription opioids);
• Have used opioids other than as specifically prescribed within thirty days prior to consent
• Seeking treatment for opioid dependence;
• Able to provide written informed consent;
• Able to speak English sufficiently to understand the study procedures.

Exclusion Criteria:

• Serious medical, psychiatric or substance use disorder that, in the opinion of the Site PI, would make participation hazardous to the participant, compromise study findings or prevent the participant from completing the study;
• Suicidal or homicidal ideation that requires immediate attention;
• Maintenance on methadone at doses of 30mg or greater at the time of signing consent;
• Presence of pain of sufficient severity as to require ongoing pain management with opioids;
• Pending legal action or other reasons that might prevent an individual from completing the study;
• If female, currently pregnant or breastfeeding or planning on conception;
• Prior participation in parent trial CTN-0051

Participants will be a convenience sample of up to three hundred sixty (360) opioid dependent patients leaving detoxification or short-term residential units at sites participating in CTN-0051. Up to 60 participants will be recruited at each of approximately six sites.