The aim of this study is to determine the effect of continuation of buprenorphine/naloxone in patients with history of Opioid Use Disorder (OUD) scheduled for surgery compared to reduced dose buprenorphine/naloxone prior to surgery on pain scores, opioid consumption, depressive symptoms and severity of substance use dependence- including record of problematic use of any non-prescribed opioids, alcohol and illicit narcotics.

Opioid use disorder (OUD) is characterized by non-remitting cycles of remission and opioid abuse relapse. It is associated with a high rate of psychiatric and physical co-morbidity when left untreated. Buprenorphine and buprenorphine/naloxone are effective opioid maintenance therapy (OMT) for OUD, however, treatment of acute post-surgical pain in patients taking buprenorphine is perceived to be challenging. Although not substantiated in clinical studies, the combination of high receptor binding affinity, long half-life, and partial mu opioid receptor agonism with buprenorphine/naloxone are thought to inhibit the analgesic actions of full mu opioid receptor agonists, potentially making standard postoperative pain control strategies less effective. There is no evidence based standard of care for optimal acute pain management strategies for patients taking buprenorphine and most recommendations are based upon provider opinion- occasionally conflicting along specialty lines. Some providers, mainly consisting of surgeons and anesthesiologists, recommend that buprenorphine should be discontinued at least 72 hours prior to elective surgery and replaced with low dose opioid agonists, in the interim. Other providers, mainly comprising of psychiatrists, contend that these patients should be maintained on buprenorphine throughout the peri-operative period at either a full or reduced dose to prevent an indeterminate risk of substance abuse relapse that can occur as consequence to the abrupt termination buprenorphine in the highly stressful surgical period. This study aims to inform this important unresolved question in the clinical care of this growing population. The investigators seek to determine the effectiveness of managing postoperative pain in patients with OUD where buprenorphine/naloxone is continued perioperatively compared to patients where buprenorphine/naloxone is reduced to a lower dose. Longitudinally, the investigators also intend to determine if there is a difference in substance abuse relapse in patients where buprenorphine/naloxone is continued vs. held by using self assessments and communication with the participant's buprenorphine provider.

Inclusion Criteria:

• currently taking buprenorphine or buprenorphine/naloxone daily for treatment of opioid use disorder by DSM-V criteria
• on buprenorphine or buprenorphine/naloxone dose of greater than 8mg for at least 30 days
• ASA health class I-III

Exclusion Criteria:

• Unable to consent to the study
• Significant pulmonary or cardiac disease
• Renal insufficiency with a glomerular filtration rate less than 30ml/min
• Liver cirrhosis with a Model for End-Stage Liver Disease (MELD) score of greater than 25

IPD will only be available to researchers involved in the study. All data will be collected and stored securely using the Redcap system to preserve privacy and confidentiality. Information regarding substance abuse history, including illicit narcotic use, will remain confidential and personal identifiers will be removed during data storage. Only members of the research team will have access to the data that participants have consented to provide. Participants will be informed that they have the right to not answer any question that makes them feel uncomfortable.