Ketamine for Opioid Use Disorder

Tonic craving (FORCAST) total scores

Faceted Opioid Research Craving Assessment for Substance use Treatment (FORCAST): A 26-item assessment of tonic craving that the person reports having felt over the prior one or two weeks. Participants indicate how much they disagree or agree with each statement on a scale that ranges from 0-6, with 0 representing "strongly disagree", 3 representing "neither agree nor disagree", and 6 representing "strongly agree". Higher scores indicate higher levels of craving. The minimum score is 0, and the maximum scores for each of the subscales are as follows: Preoccupation: 24 Negative Reinforcement: 30 Positive Reinforcement: 24 Motivation: 30 Lack of control: 24 Uneasiness: 24 Maximum total score for all subscales = 156

Severity of depression symptoms

Montgomery-Asberg Depression Rating Scale (MADRS): a 10-item questionnaire of depression severity. The total score ranges from 0-60, with scores of 0-6 considered normal (non-depressed), 7-19 indicative of mild depression, 20-34 indicative of moderate depression, and 35-60 indicative of severe depression. Item 10 on the instrument will be used to monitor any changes in suicidal ideation throughout the trial.

Cue-induced craving scores

Cue Reactivity Paradigm: our drug cue reactivity paradigm will be designed to elicit an acute craving state. We will present a series of opioid cue images continuously (total time \<5 min) via computer or tablet. Cues will be personalized based on each individual's drug use history as derived from baseline clinical assessments. For example, if a participant had no history of intravenous drug injection, we will not present opioid cue images containing injection paraphernalia like needles and instead will present images with opioid pills and/or powder. At the end of each one-minute session, participants will be asked to rate, on a scale of 1-10, "How much did you like the images you saw?", "How much do you want to use right now?", "How much do you want to avoid using right now?", "How much control do you feel you have over using right now" and "What is the maximum amount you would pay right now for a single dose of what you saw?"

Chronic pain ratings

Graded Chronic Pain Scale (GCPS): a six-item instrument that evaluates chronic pain severity (intensity and impact on life activities).

Number of methadone doses received at 90 days post final ketamine session

Study team will have access to clinic records to assess the number of methadone doses patients have received at 90 days post final ketamine session

Decision making test performance (risk and ambiguity tolerance)

Choice under risk and ambiguity (CRA) decision making task: On each trial, participants choose between a guaranteed $1 and a lottery. Each lottery has 2 possible outcomes: v or $0, where v ranges from $1.20 to $13.20. On half of the trials, v could be received with 1 of 3 known probabilities (p: 25%, 50%, or 75%); on the other half, the probability information is occluded and thus incompletely known (the ambiguity context). There are 3 levels of ambiguity: low (24% unknown), medium (50% unknown), and high (74% unknown). In reality, the true underlying probability in ambiguity trials is fixed at 50%. Different combinations of v, risk level, and ambiguity level are presented for 30 trials total. A modified utility model will be used which can extract the following parameters from participant decisions on these trials: * risk tolerance * ambiguity tolerance * choice stochasticity

Methadone dose (mg) at 90 days post final ketamine session

Study team will have access to clinic records of methadone dose (mg) received by participant at 90 days post final ketamine session

OUD treatment outcomes at 6-, 9-, and 12 months post study enrollment

Study team will have access to clinic records of methadone dose, number of methadone doses received, and frequency of negative drug screens though 12 months post study enrollment