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Trial registered on ANZCTR


Registration number
ACTRN12619000537156
Ethics application status
Approved
Date submitted
2/04/2019
Date registered
4/04/2019
Date last updated
10/03/2020
Date data sharing statement initially provided
4/04/2019
Date results information initially provided
10/03/2020
Type of registration
Retrospectively registered

Titles & IDs
Public title
Non-specific effects and mechanisms of mindfulness meditation for experimental pain
Scientific title
A randomized controlled balanced placebo design comparing the effects of treatment expectancies in mindfulness vs sham mindfulness on experimental pain in healthy adults
Secondary ID [1] 297776 0
None
Universal Trial Number (UTN)
Trial acronym
Linked study record
This study is a follow-up study to ACTRN12618001175268

Health condition
Health condition(s) or problem(s) studied:
Pain 312123 0
Condition category
Condition code
Anaesthesiology 310676 310676 0 0
Pain management
Musculoskeletal 310677 310677 0 0
Other muscular and skeletal disorders
Alternative and Complementary Medicine 310678 310678 0 0
Other alternative and complementary medicine

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Participants will complete 6 x 20-minute guided-audio-delivered mindfulness meditation training sessions (over a 7-10 day period).

We will manipulate meditation type (mindfulness meditation, sham mindfulness meditation) and instruction (active condition, placebo condition) in a (2x2)+1 balanced placebo design, such that participants will receive a combination of the following:

MEDITATION TYPE

GM – Get Mindfulness Meditation: participants receive training in a ‘focussed attention’ mindfulness meditation technique taught as means to reduce pain intensity and unpleasantness;

or

GS – Get Sham (Placebo) Mindfulness Meditation: participants receive training in an active control condition that matches real mindfulness meditation on all aspects but lacks the proposed ‘active ingredient’ of the training (the practice does not provide an anchor for attention or instructions on how to relate mindfully to present moment experience). This is delivered as a means to elicit placebo-mediated (but not mindfulness-mediated) reductions in pain intensity and unpleasantness.

AND

INSTRUCTION

TM – Told Mindfulness: participants are given instructions (regardless of which intervention they actually receive) that lead them to expect they are receiving a highly effective active mindfulness intervention (‘you will receive a new evidence-based mindfulness intervention that is highly effective for reducing pain’);

or

TS – Told Sham: participants are given instructions (regardless of which intervention they actually receive) that lead them to expect they are receiving the minimally effective sham (placebo) mindfulness intervention (‘you will receive placebo mindfulness intervention that lacks specific ‘active ingredients’ of the mindfulness intervention. You will likely find this training enjoyable and relaxing, but it is not expected to be effective for pain.’)

This results in FOUR groups:

1) TM-GM (Told mindfulness-Get mindfulness): this group should demonstrate additive effects of mindfulness AND expectancy;

2) TS-GM (Told sham-Get mindfulness): this group should demonstrate mindfulness effects WITHOUT expectancy effects;

3) TM-GS (Told mindfulness-Get sham): this group should demonstrate expectancy effects WITHOUT mindfulness effects;

4) TS-GS (Told sham-Get sham): this group should demonstrate neither mindfulness or expectancy effects.

In all FOUR treatment groups (TM-GM, TS-GM, TM-GS, TS-GS), participants receive 2 x in-lab training sessions (one at baseline and one immediately before post-test) and are asked to complete 4 x training sessions at home in between experimental sessions. Home guided-audio training is delivered via online survey software and adherence is monitored. All guided-training sessions are delivered by a qualified mindfulness instructor with 4+ years’ experience.

5) Finally, we will include an additional no treatment control group (NTC) - this group completes no training and receives minimal instruction with no suggestion of benefit. They listen to a 20-minute podcast at baseline and immediately before post-test (This American Life - Psychic Buddha; https://www.thisamericanlife.org/212/the-other-man/act-one-0) and post-test (ABC Radio National - Who Owns Mindfulness?; http://www.abc.net.au/radionational/programs/earshot/who-ownsmindfulness/9024864) to maintain experimenter blinding only. So as not to manipulate participant expectancy, these podcasts do not discuss any benefits of mindfulness.
Intervention code [1] 314015 0
Treatment: Other
Comparator / control treatment
sham mindfulness meditation; no-treatment control group
Control group
Placebo

Outcomes
Primary outcome [1] 319522 0
Pain unpleasantness, assessed via a numerical rating scale
Timepoint [1] 319522 0
Pre to post-treatment, i.e., baseline and after 6 sessions of training (1 week)
Secondary outcome [1] 368565 0
Pain intensity, assessed via a numerical rating scale
Timepoint [1] 368565 0
Pre to post-treatment, i.e., baseline and after 6 sessions of training (1 week)
Secondary outcome [2] 368566 0
Pain threshold, assessed using pain threshold test (Pathway CHEPS, Medoc, Israel).
Timepoint [2] 368566 0
Pre to post-treatment, i.e., baseline and after 6 sessions of training (1 week)
Secondary outcome [3] 368567 0
Pain tolerance, assessed using pain tolerance test (Pathway CHEPS, Medoc, Israel).
Timepoint [3] 368567 0
Pre to post-treatment, i.e., baseline and after 6 sessions of training (1 week)
Secondary outcome [4] 368568 0
Mindfulness, assessed via the FFMQ
Timepoint [4] 368568 0
Pre to post-treatment, i.e., baseline and after 6 sessions of training (1 week)
Secondary outcome [5] 368569 0
Depression, assessed via the DASS-21
Timepoint [5] 368569 0
Pre to post-treatment, i.e., baseline and after 6 sessions of training (1 week)
Secondary outcome [6] 368570 0
Anxiety, assessed via the DASS-21
Timepoint [6] 368570 0
Pre to post-treatment, i.e., baseline and after 6 sessions of training (1 week)
Secondary outcome [7] 368571 0
Stress, assessed via the DASS-21
Timepoint [7] 368571 0
Pre to post-treatment, i.e., baseline and after 6 sessions of training (1 week)
Secondary outcome [8] 368572 0
Pain related cognitive processes, assessed via the PCPQ
Timepoint [8] 368572 0
Pre to post-treatment, i.e., baseline and after 6 sessions of training (1 week)
Secondary outcome [9] 368573 0
Expectancy, assessed via self-report questions
Timepoint [9] 368573 0
Pre to post-treatment, i.e., baseline and after 6 sessions of training (1 week)

Eligibility
Key inclusion criteria
(1) at least 18 years of age; (2) pain-free (defined as 3/10 or lower on NRS); (3) not currently taking analgesic or psychotropic medications; (4) be able to read, speak and understand English; and (5) be able to attend two experimental sessions over 2 consecutive weeks and four sessions of home-practice.
Minimum age
18 Years
Maximum age
No limit
Gender
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
(1) currently taking analgesic or psychotropic medications; (2) current pain higher than 3/10 on NRS; (3) pregnant or breastfeeding; (4) current mindfulness or meditation practice (average >20 min/week in last six months); (5) previously completed a mindfulness course (e.g. MBSR, Vipassana); and (6) practicing a meditation-based religion (e.g. Hinduism, Buddhism, contemplative Christianity);

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)
Computerised random sequence generation (https://www.randomizer.org/) with numbers generated using a complex algorithm seeded by the computer's clock.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?

The people administering the treatment/s
The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Parallel
Other design features
Phase
Not Applicable
Type of endpoint(s)
Efficacy
Statistical methods / analysis
SAMPLE SIZE CALCULATIONS
Power analyses were based on the effect sizes for mindfulness versus either sham mindfulness or natural history control from six recent studies on experimentally-induced pain (Kingston, Chadwick, Meron, & Skinner, 2007; Liu, Wang, Chang, Chen, & Si, 2013; MacCoon et al., 2012; Zeidan, 2016; Zeidan et al., 2011, 2015). These studies had a mean effect size of d=0.899 for pain unpleasantness and d=0.514 for pain intensity. To be conservative, we used the smaller of these (i.e. d=0.514) to calculate sample size. This indicated that 28 participants per group would be required to have 90% power to detect a significant effect of mindfulness versus sham mindfulness of this magnitude. We therefore aim to recruit 30 participants per group to allow for 5-10% attrition.

BASELINE CHARACTERISTICS
Chi-squared tests and independent samples t-tests will be used to compare baseline characteristics across the three groups.

PRIMARY AND SECONDARY OUTCOMES
Changes in primary and secondary outcome measures between the pre and post-treatment phases will be analysed using one-way, 5-level ANCOVAs with treatment (TM-GM, TS-GM, TM-GS, TS-GS, NTC) as the independent variable and baseline score on the relevant outcome as a covariate.

Orthogonal contrast analysis will be used to compare changes across groups. These contrasts will create a nested 2x2 ANOVA to test the main effects and interaction of meditation type (GM vs GS) and instruction (TM vs TS) as well as an additional contrast comparing the effect of any treatment to no treatment.

Specifically, these contrasts will test:
1) Whether any treatment differs from no treatment (TM-GM + TS-GM + TM-GS + TS-GS vs NTC);
2) Whether there is a main effect of real vs sham mindfulness (TM-GM + TS-GM vs TM-GS + TS-GS);
3) Whether there is a main effect of instruction (TM-GM + TM-GS vs TS-GM + TS-GS); and
4) Whether there is an interaction between treatment and instruction.

The contrast values for these contrasts (with groups ordered as TM-GM, TM-GS, TS-GM, TS-GS, NTC) are as follows:
1) Any effect vs no treatment: 1, 1, 1, 1, -4;
2) Main effect of mindfulness: 1, -1, 1, -1, 0;
3) Main effect of instruction: 1, 1, -1, -1, 0;
4) Interaction between mindfulness and instruction: 1, -1, -1, 1, 0.

Other baseline characteristics that have a p-value of <0.1 when comparing the five groups will be included as covariates in these analyses.

EXPLORATORY MEDIATOR ANALYSIS
Where any significant differences are found in these analyses on our primary or secondary pain outcomes, we will conduct exploratory mediator analysis to determine whether mindfulness, depression, anxiety, stress, pain related cognitive processes or expectancy mediate the effect of the intervention on those outcomes. This will be implemented via Preacher and Hayes/PROCESS Model.

Recruitment
Recruitment status
Completed
Date of first participant enrolment
Anticipated
Actual
Date of last participant enrolment
Anticipated
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
NSW

Funding & Sponsors
Funding source category [1] 302300 0
University
Name [1] 302300 0
University of Sydney
Address [1] 302300 0
The University of Sydney
Camperdown NSW 2006
Country [1] 302300 0
Australia
Primary sponsor type
University
Name
The University of Sydney
Address
The University of Sydney
Camperdown NSW 2006
Country
Australia
Secondary sponsor category [1] 302290 0
None
Name [1] 302290 0
Address [1] 302290 0
Country [1] 302290 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 302974 0
University of Sydney Human Research Ethics Committee
Ethics committee address [1] 302974 0
Human Ethics Office
Margaret Telfer Building (K07)
University of Sydney
Camperdown NSW 2006
Ethics committee country [1] 302974 0
Australia
Date submitted for ethics approval [1] 302974 0
Approval date [1] 302974 0
08/09/2017
Ethics approval number [1] 302974 0
2017/640

Summary
Brief summary
As many as 1 in 4 Australians experience chronic pain. There is a critical need for the development and evaluation of fast-acting non-pharmaceutical treatments that have the capacity to target the multidimensional nature of chronic pain. This study will investigate how beliefs or expectations about the effects of mindfulness meditation interact with the actual effects of training in the technique, and will further characterise the mechanisms underlying these effects. Results will ultimately lead to targeted interventions that more effectively engage cognitive mechanisms associated with pain attenuation.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 92034 0
Mr Jonathan Davies
Address 92034 0
Top South Badham Building (A16)
School of Psychology
The University of Sydney
Camperdown NSW 2006
Country 92034 0
Australia
Phone 92034 0
+61 2 9351 7950
Fax 92034 0
Email 92034 0
j.davies@sydney.edu.au
Contact person for public queries
Name 92035 0
Mr Jonathan Davies
Address 92035 0
Top South Badham Building (A16)
School of Psychology
The University of Sydney
Camperdown NSW 2006
Country 92035 0
Australia
Phone 92035 0
+61 2 9351 7950
Fax 92035 0
Email 92035 0
j.davies@sydney.edu.au
Contact person for scientific queries
Name 92036 0
Mr Jonathan Davies
Address 92036 0
Top South Badham Building (A16)
School of Psychology
The University of Sydney
Camperdown NSW 2006
Country 92036 0
Australia
Phone 92036 0
+61 2 9351 7950
Fax 92036 0
Email 92036 0
j.davies@sydney.edu.au

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No
No/undecided IPD sharing reason/comment
We do not currently have ethics approval to share this data. We will seek a modification to make IPD available.
What supporting documents are/will be available?
No other documents available
Summary results
Have study results been published in a peer-reviewed journal?
No
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary