Investigators will conduct a hybrid type 1 effectiveness-implementation study, using a pragmatic, open-label, randomized controlled trial (RCT). Investigators will randomize 270 hospitalized patients with (a) chronic pain and (b) opioid misuse or opioid use disorder (OUD) to a 5-day BUP microdose induction protocol (without stopping full agonists) or 2-day standard induction (with stopping full agonists), and then link participants to outpatient BUP treatment when they are released from the hospital. Study assessment visits will occur at baseline, 1 week, and 1, 3, and 6 months. Assessments will include interviews and urine drug tests to determine whether participants start BUP, continue BUP, have improvements in pain and decrease illicit opioid use. During induction and 3-months of follow-up, investigators will also collect data on mobile devices to assess opioid withdrawal, opioid craving, pain, and anxiety. These data will allow investigators to assess whether BUP microdosing targets of engagement-opioid- and pain-related symptoms-mediate OUD outcomes. Exploratory analyses will also examine pain as a trigger for opioid relapse.~Aim 1: To test the effectiveness of BUP microdose induction (vs. TAU) on OUD outcomes.~H1: The microdose arm (vs. TAU) will have better BUP treatment uptake and retention, and less illicit opioid use.~H2: Improvements in H1 will be mediated by opioid- and pain-related symptoms.~Aim 2: To test the effectiveness of microdosing (vs. TAU) on pain outcomes. H3: The microdose arm (vs. TAU) will have less pain intensity and interference, and improved quality of life.~H4: Improvements in H3 will be mediated by OUD outcomes.~Aim 3: To inform future implementation and dissemination efforts, investigators will:~3a) Examine factors influencing reach, adoption, implementation, and maintenance of BUP microdosing. Investigators will use qualitative and quantitative methods to describe multi-level factors influencing these domains; 3b) Calculate the cost and examine cost-effectiveness of BUP microdosing. H5: Compared with TAU, BUP microdosing will be cost-effective from a societal and a health sector perspective.
Investigators will test a novel protocol for starting BUP (buprenorphine-naloxone) treatment. The BUP microdose induction protocol has participants start very low doses of BUP without stopping other opioids that they are taking. The treatment as usual (TAU) has participants stop other opioids and experience opioid withdrawal before starting BUP. Investigators propose to test BUP microdose inductions vs. TAU in a randomized controlled trial.