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Trial registered on ANZCTR


Registration number
ACTRN12623000801617
Ethics application status
Approved
Date submitted
11/07/2023
Date registered
26/07/2023
Date last updated
26/07/2023
Date data sharing statement initially provided
26/07/2023
Type of registration
Prospectively registered

Titles & IDs
Public title
What are the effects of an open-label placebo on pain?
Scientific title
What are the effects of an open-label placebo on pain? A three-arm parallel randomised controlled trial on healthy adults.
Secondary ID [1] 310089 0
None
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
pain 330641 0
Condition category
Condition code
Anaesthesiology 327465 327465 0 0
Pain management

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
There will be one 45-minute session for the participants with the researcher. After completing the baseline questionnaire, participants will be randomised to three conditions.

Arm 1: Control group, receives no placebo pills and no explanation about placebos.

Arm 2: Experimental group, will be asked to take two placebo pills containing microcrystalline cellulose while supervised by the researcher. A standard verbal explanation about open-label placebos will be given by the researcher, explaining the effects a placebo might have in reducing their pain. This explanation will take approximately 15 minutes.

Arm 3: Experimental group, will be asked to take two placebo pills containing microcrystalline cellulose while supervised by the researcher. A standard verbal explanation about open-label placebos will be given by the researcher, explaining the effects a placebo might have in reducing their pain. In addition to this, they have a short additional explanation suggesting them to keep an open mind about the treatment. This explanation will take approximately 15 minutes, with the additional explanation by the researcher suggesting the participant keep an open mind taking approximately 30 seconds.

After being randomised and undergoing their conditions, all participants will be asked to fill out a post-allocation questionnaire.

After this, all participants will undergo a cold pressor pain test which involves placing one of their hands into water cooled to 3 degrees.

During the test they will be assessed for pain intensity, pain tolerance (how long they keep their hand in), whether they remove their hand before the maximum time, and pain threshold (time until first feel pain).
Intervention code [1] 326494 0
Treatment: Other
Comparator / control treatment
The control group does not receive any placebo pills, nor any explanation about placebos.
Control group
Active

Outcomes
Primary outcome [1] 335337 0
Pain intensity measured by a 0-10 numeric rating scale.
Timepoint [1] 335337 0
15 seconds into the cold pressor pain test, as well at time points of 45, 75 and 106 seconds into the task.
Primary outcome [2] 335338 0
Participants' expectations of treatment measured 2 items on a 0-10 numeric rating scale.
Timepoint [2] 335338 0
At one time point, after they have undergone their group condition.
Primary outcome [3] 335393 0
Participants' openness to treatment, measured by 1 item on a 0-10 numeric rating scale.
Timepoint [3] 335393 0
At one time point, after they have undergone their group condition.
Secondary outcome [1] 423989 0
Withdrawal (whether participants removed their hand from the water bath before the maximum time). This is recorded as a categorical Y/N
Timepoint [1] 423989 0
During the cold pressor pain test.
Secondary outcome [2] 423990 0
Pain tolerance, the time in seconds, measured by a digital stopwatch, that the participant holds their hand in the water.
Timepoint [2] 423990 0
During the cold pressor pain test.

Eligibility
Key inclusion criteria
To be eligible for the study, participants must be English-speaking adults aged 18 or over, who are willing to undergo an experimentally induced pain paradigm.

Minimum age
18 Years
Maximum age
No limit
Sex
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
Participants will be excluded if they have chronic pain conditions, cognitive impairment, lack of sensation in hands, open sores, amputations, health issues that may be exacerbated by cold-exposure, or who are currently taking pain medication.

Study design
Purpose of the study
Treatment
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Sealed opaque envelopes.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Simple randomisation using a randomisation table created by computer software (i.e. computerised sequence generation).
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?

The people administering the treatment/s

Intervention assignment
Parallel
Other design features
Phase
Not Applicable
Type of endpoint/s
Efficacy
Statistical methods / analysis

A power analysis was conducted to calculate the required sample size.

Data will be analysed by mixed model ANCOVA in IBM SPSS v29 to detect differences between groups on pain.

If any differences are found between groups, this will be investigated closer via post-hoc analyses with appropriate Bonferroni corrections.

Recruitment
Recruitment status
Not yet recruiting
Date of first participant enrolment
Anticipated
31/07/2023
Actual
Date of last participant enrolment
Anticipated
11/09/2023
Actual
Date of last data collection
Anticipated
11/09/2023
Actual
Sample size
Target
42
Accrual to date
Final
Recruitment outside Australia
Country [1] 25633 0
New Zealand
State/province [1] 25633 0
Auckland

Funding & Sponsors
Funding source category [1] 314251 0
University
Name [1] 314251 0
The University of Auckland
Country [1] 314251 0
New Zealand
Primary sponsor type
University
Name
The University of Auckland
Address
85 Park Road, Grafton, Auckland, New Zealand, 1023
Country
New Zealand
Secondary sponsor category [1] 316187 0
None
Name [1] 316187 0
Address [1] 316187 0
Country [1] 316187 0
Other collaborator category [1] 282751 0
Individual
Name [1] 282751 0
Professor Keith Petrie
Address [1] 282751 0
The University of Auckland
M&HS BUILDING 503 - Bldg 503
Level 3, Room 320
85 PARK RD
GRAFTON
AUCKLAND 1023
New Zealand
Country [1] 282751 0
New Zealand

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 313371 0
Auckland Health Research Ethics Committee
Ethics committee address [1] 313371 0
Ethics committee country [1] 313371 0
New Zealand
Date submitted for ethics approval [1] 313371 0
19/05/2023
Approval date [1] 313371 0
28/06/2023
Ethics approval number [1] 313371 0
25992

Summary
Brief summary
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 127910 0
Prof Keith Petrie
Address 127910 0
The University of Auckland
M&HS Building 507
Level 3, Room 320
85 Park Road, Grafton
Auckland 1023
Country 127910 0
New Zealand
Phone 127910 0
+64 49 923 6564
Fax 127910 0
Email 127910 0
kj.petrie@auckland.ac.nz
Contact person for public queries
Name 127911 0
Keith Petrie
Address 127911 0
The University of Auckland
M&HS Building 507
Level 3, Room 320
85 Park Road, Grafton
Auckland 1023
Country 127911 0
New Zealand
Phone 127911 0
+64 49 923 6564
Fax 127911 0
Email 127911 0
kj.petrie@auckland.ac.nz
Contact person for scientific queries
Name 127912 0
Keith Petrie
Address 127912 0
The University of Auckland
M&HS Building 507
Level 3, Room 320
85 Park Road, Grafton
Auckland 1023
Country 127912 0
New Zealand
Phone 127912 0
+64 49 923 6564
Fax 127912 0
Email 127912 0
kj.petrie@auckland.ac.nz

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No
No/undecided IPD sharing reason/comment


What supporting documents are/will be available?

No Supporting Document Provided



Results publications and other study-related documents

Documents added manually
No documents have been uploaded by study researchers.

Documents added automatically
No additional documents have been identified.