Observational Study of Ketamine Infusions for the Treatment of Chronic Pain

Ketamine Infusion for the Treatment Chronic Pain in Adults: a Prospective Observational Study to Characterize Predictors and Outcomes

This observational study will collect prospectively specified data on patient characteristics and clinically relevant outcomes in patients who receive a ketamine infusion at Stanford Pain Management Center for the treatment of chronic pain, with the goal of identifying treatment responders and relationships between patient characteristics and treatment response.

Study Overview

• Status: Enrolling by invitation
• Conditions: Chronic Pain
• Intervention / Treatment: Drug: Ketamine

Detailed Description

Ketamine is a type of anesthetic drug which has been used off-label to treat chronic pain. The effectiveness of intravenous ketamine and its duration of effect are not well-understood. There is high variability in response to ketamine, and it remains unclear which patient characteristics are associated with favorable outcomes. This observational study will collect a wide range of patient-reported outcomes via digital surveys: once at baseline before treatment, and up to 7 follow-up surveys for up to 12 months following a single ketamine infusion. Survey data will be supplemented by clinical data obtained from electronic medical records.

• Study Type: Observational
• Enrollment (Estimated): 100

Contacts and Locations

Study Locations

• United States
  • California
    • Stanford, California, United States, 94305
      • Stanford University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No

• Sampling Method: Probability Sample

Study Population

This study population consists of adults who receive a ketamine infusion for the treatment of any chronic pain condition. All patients who are scheduled for a ketamine infusion through Stanford's Pain Management Center during this study's enrollment period are contacted for screening.

Description

Inclusion Criteria:

• Has been seen at Stanford's Pain Management Center for a doctor's visit at least once.
• Is scheduled to undergo at least 1 ketamine infusion for the treatment of any chronic pain condition.
• Have a valid email address and consents to receiving surveys by email.
• Able to read, understand, and respond to English-language surveys on an electronic device such as a cell phone, tablet, or computer.
• Able to read, understand, and provide written, dated informed consent.

Exclusion Criteria:

• Has their ketamine infusion cancelled, which may occur before or after consenting to this study.

Study Plan

How is the study designed?

Design Details

• Observational Models: Case-Only
• Time Perspectives: Prospective

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Open label ketamine; Patients who receive a ketamine infusion for the treatment of chronic pain in the course of usual clinical care	Drug: Ketamine; A multi-day continuous ketamine infusion delivered intravenously at subanesthetic doses in a monitored setting; Other Names: Ketalar

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from baseline Patient Global Impression of Change (PGIC) in overall status; measured with PGIC Scale	The PGIC Scale is a single-question 7-point Likert scale ranging from "Very much improved" to "Very much worse."	1 week, 2 weeks, 1 month, 2 months, 3 months, 6 months, 12 months (or up to the time of their next ketamine infusion)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from baseline average pain intensity; measured with Numeric Rating Scale (NRS)	Participants rate their average pain intensity over the last 7 days using whole numbers on a 0-to-10 scale, with higher values indicative of more pain.	1 week, 2 weeks, 1 month, 2 months, 3 months, 6 months, 12 months (or up to the time of their next ketamine infusion)

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from baseline opioid use; measured with 2 questions	Question 1: Participants are asked whether they have used any opioid medications since their last ketamine infusion (yes/no). Question 2: Participants are asked to rate how their opioid use has changed on a 4-point scale ranging from "I have not used any opioids since my last ketamine infusion" to "I am using more opioids after my last ketamine infusion."	1 week, 2 weeks, 1 month, 2 months, 3 months, 6 months, 12 months (or up to the time of their next ketamine infusion)
Change from baseline pain catastrophizing score; measured with Pain Catastrophizing Scale - Short Form	Pain Catastrophizing Scale - Short Form is a 4-item scale with a total score ranging from 0-16, with higher scores indicative of more catastrophizing.	1 week, 2 weeks, 1 month, 2 months, 3 months, 6 months, 12 months (or up to the time of their next ketamine infusion)
Change from baseline pain interference score; measured with PROMIS Pain Interference	PROMIS Pain Interference is a computerized adaptive test with results reported as a T-score (mean score of 50 and standard deviation of 10), with higher T-scores indicative of more pain interference.	1 week, 2 weeks, 1 month, 2 months, 3 months, 6 months, 12 months (or up to the time of their next ketamine infusion)
Change from baseline physical function score; measured with PROMIS Physical Function	PROMIS Physical Function is a computerized adaptive test with results reported as a T-score (mean score of 50 and standard deviation of 10), with higher T-scores indicative of better physical function.	1 week, 2 weeks, 1 month, 2 months, 3 months, 6 months, 12 months (or up to the time of their next ketamine infusion)
Change from baseline depression score; measured with PROMIS Depression	PROMIS Depression is a computerized adaptive test with results reported as a T-score (mean score of 50 and standard deviation of 10), with higher T-scores indicative of more depression.	1 week, 2 weeks, 1 month, 2 months, 3 months, 6 months, 12 months (or up to the time of their next ketamine infusion)
Change from baseline anxiety score; measured with PROMIS Anxiety	PROMIS Anxiety is a computerized adaptive test with results reported as a T-score (mean score of 50 and standard deviation of 10), with higher T-scores indicative of more anxiety.	1 week, 2 weeks, 1 month, 2 months, 3 months, 6 months, 12 months (or up to the time of their next ketamine infusion)
Change from baseline sleep disturbance score; measured with PROMIS Sleep Disturbance	PROMIS Sleep Disturbance is a computerized adaptive test with results reported as a T-score (mean score of 50 and standard deviation of 10), with higher T-scores indicative of more sleep disturbance.	1 week, 2 weeks, 1 month, 2 months, 3 months, 6 months, 12 months (or up to the time of their next ketamine infusion)
Change from baseline global health score; measured with PROMIS Global Health	PROMIS Global Health is a computerized adaptive test with results reported as a T-score (mean score of 50 and standard deviation of 10), with higher T-scores indicative of better overall physical health, mental health, social health, pain, fatigue, and overall perceived quality of life.	1 week, 2 weeks, 1 month, 2 months, 3 months, 6 months, 12 months (or up to the time of their next ketamine infusion)
Change from baseline body areas affected by pain; measured with CHOIR Body Map	CHOIR Body Map is a validated self-report body map where participants select areas of the body affected by pain, with a higher number of selected areas indicative of more widespread pain.	1 week, 2 weeks, 1 month, 2 months, 3 months, 6 months, 12 months (or up to the time of their next ketamine infusion)

Collaborators and Investigators

• Sponsor: Theresa Lii
• Investigators: Principal Investigator: Theresa Lii, MD, Stanford University

Study record dates

Study Major Dates

• Study Start (Actual): June 1, 2022
• Primary Completion (Estimated): December 31, 2026
• Study Completion (Estimated): December 31, 2026

Study Registration Dates

• First Submitted: July 21, 2022
• First Submitted That Met QC Criteria: July 25, 2022
• First Posted (Actual): July 27, 2022

Study Record Updates

• Last Update Posted (Estimated): December 19, 2025
• Last Update Submitted That Met QC Criteria: December 12, 2025
• Last Verified: December 1, 2025

More Information

Terms related to this study

• Keywords: chronic pain; ketamine; neuropathic pain; complex regional pain syndrome; pain syndrome; intractable pain
• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Nervous System Diseases; Mental Disorders; Neuromuscular Diseases; Peripheral Nervous System Diseases; Autonomic Nervous System Diseases; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Somatoform Disorders; Chronic Pain; Neuralgia; Pain, Intractable; Complex Regional Pain Syndromes; Organic Chemicals; Hydrocarbons; Cyclohexanes; Cycloparaffins; Hydrocarbons, Alicyclic; Hydrocarbons, Cyclic; Ketamine
• Other Study ID Numbers: 62561

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Individual participant data that underlie the results reported in the publication, after deidentification (text, tables, figures, and appendices).
• IPD Sharing Time Frame: Immediately following publication. No end date.
• IPD Sharing Access Criteria: IPD may be shared upon reasonable request to researchers who provide a methodologically sound proposal.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; ANALYTIC_CODE

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No