Feasibility and Acceptability of OLP-EXP in Chronic Pain

August 21, 2026 updated by: University of Maryland, Baltimore

Evaluating the Feasibility and Acceptability of Expectation-optimized Open-label Placebo as an Adjuvant Treatment for Chronic Pain

The primary objective is to determine the feasibility of delivering OLP-EXP, EXP only, and OLP only over 6 weeks to adults with chronic TMD. The trial will be considered feasible for progression planning when the 6-week retention rate is at least 80% in each arm and average OLP pill adherence is at least 80% of prescribed days in each OLP arm.

Primary hypothesis: Each intervention arm will meet the prespecified 6-week retention benchmark, and each OLP arm will meet the prespecified pill-adherence benchmark.

The secondary objectives are:

  1. To evaluate acceptability of each intervention using the TFA measurement and semi-structured interviews.
  2. To assess the feasibility of collecting daily EMA, continuous actigraphy, weekly questionnaires, and 3-, 6-, and 12-month follow-up assessments.
  3. To identify intervention barriers, facilitators, perceived benefits, burden, ethical concerns, and recommendations for a future fully powered efficacy trial.
  4. To estimate variability, missingness, and measure reliability needed to select outcomes and design a future trial.

Study Overview

Status

Not yet recruiting

Detailed Description

Pain lasting for more than 3 months becomes chronic, and is prevalent across the global population. Among chronic pain conditions, temporomandibular disorders (TMD), a common orofacial pain condition affecting 9 to 30% of the general population, have attracted the attention of clinical providers and researchers. The high incidence and disastrous consequences of TMD underscore the need for effective and safe treatments.

Clinical and mechanistic research has shown substantial placebo responses in pain trials, highlighting the great potential to harness placebo mechanisms in clinical care. For example, a meta-analysis estimated that placebo responses could account for up to 66% of observed improvement in migraine-related outcomes.8 In one efficacy and safety trial of an intravenously eptinezumab, as much as 74% of the apparent benefit was attributed to placebo responses.

In ethically translating placebo mechanisms, open-label placebo (OLP) offers an adjuvant to current pharmacological and psychological treatments for chronic pain. OLP refers to the transparent, honest administration of placebos. Studies have found that people can still experience improvements in symptoms even after receiving OLP.

Previous RCT has demonstrated efficacy of EXPECT in a pilot clinical trial showing a reduction in the length of hospital stay after cardiac surgery. Moreover, participants who received EXPECT showed greater improvements in disability, and reduced pro-inflammatory cytokine concentrations compared to those in the treatment as usual group.

The investigators aim to develop an expectation-optimized OLP intervention (OLP-EXP) that could potentially maximize OLP effects and yield larger improvement in managing chronic pain, and an EXP only intervention that delivers expectations induced analgesia without the negative connotations of "placebo".

The investigators hypothesize that the adapted OLP-EXP and EXP only will be feasible and well-accepted in chronic pain population.

This is a single-site, three-arm, parallel-group, randomized pilot/feasibility clinical trial. Fifty-seven adults with chronic TMD will be randomized 1:1:1 to OLP-EXP, EXP only, or OLP only. All participants will continue treatment as usual. The intervention period is 6 weeks, followed by remote assessments at 3, 6, and 12 months.

The intervention arms are:

  1. OLP-EXP: Expectation optimization addressing benefit, personal-control, and coping expectations, plus transparent daily OLP pills for 6 weeks and weekly boosters.
  2. EXP only: Expectation optimization addressing personal-control and coping expectations associated with chronic pain in general, plus weekly boosters.
  3. OLP only: Standard transparent OLP rationale and daily OLP pills for 6 weeks, with neutral matched study contacts that do not deliver expectation-optimization content.

Study Type

Interventional

Enrollment (Estimated)

57

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • English speaking (written and spoken)
  • Age between 18 and 65 years
  • Confirmed TMD for more than 3 months
  • Grade II or above on the Graded Chronic Pain Scale

Exclusion Criteria:

  • Personal (or family first degree) history of mania, schizophrenia, or other psychoses
  • Severe psychiatric conditions require medication (e.g. schizophrenia, bipolar disorders, autism) or hospitalization within the last 3 years.
  • Lifetime alcohol/drug dependence and alcohol/drug abuse in past one year
  • Pregnancy/Breastfeeding
  • Currently participating in another clinical trial

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Other
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: OLP-EXP
Expectation optimization addressing benefit, personal-control, and coping expectations, plus transparent daily OLP pills for 6 weeks and weekly boosters.
Expectation optimization addressing benefit, personal control, and coping expectations, plus transparent daily OLP pills for 6 weeks and weekly boosters.
Other Names:
  • Zeebo pills
  • Expectations optimization intervention
Experimental: EXP
Expectation optimization addressing personal-control and coping expectations associated with chronic pain in general, plus weekly boosters.
Expectation optimization addressing personal-control and coping expectations associated with chronic pain in general, plus weekly boosters.
Other Names:
  • Expectations optimization intervention
Active Comparator: OLP
Standard transparent OLP rationale and daily OLP pills for 6 weeks, with neutral matched study contacts that do not deliver expectation-optimization content.
Open-label placebo pills. The placebo pills in this study are empty capsules without any ingredients inside. The capsules are made of microcrystalline cellulose.
Other Names:
  • Zeebo pills

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Enrollment rate
Time Frame: At the enrollment
Enrollment rate: the proportion (%) of recruited participants who enrolled in the study.
At the enrollment
Retention rate
Time Frame: End of week 6
Retention rate: the proportion (%) of enrolled participants who finished the study
End of week 6
Daily survey completion rate
Time Frame: End of week 6
Module rate: the proportion (%) of completed daily surveys sent through DockTales and REDCap-based surveys.
End of week 6

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

July 1, 2027

Primary Completion (Estimated)

December 31, 2028

Study Completion (Estimated)

December 31, 2029

Study Registration Dates

First Submitted

July 24, 2026

First Submitted That Met QC Criteria

July 24, 2026

First Posted (Actual)

July 30, 2026

Study Record Updates

Last Update Posted (Actual)

August 25, 2026

Last Update Submitted That Met QC Criteria

August 21, 2026

Last Verified

August 1, 2026

More Information

Terms related to this study

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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