Does the Understanding of Placebo Mechanisms Compensate for the Loss of Efficacy Associated With Open Label Placebo

Laboratoire TIMC-IMAG126 enrolled

Overview

The investigators are investigating whether, when given detailed information about underlying placebo mechanisms and pain, subjects will have a response similar to that of those subjected to a procedure in which they receive a conventional placebo treatment (associated with deception). STUDY DESIGN: This is a non-inferior parallel, controlled and randomized, single blind trial. POPULATION: The investigators will include in the study 126 subjects without known pathology. Participants will then be divided into 2 groups on a randomized basis. METHODOLOGY: Each subject will undergo three sessions of Cold Pressure Test (CPT), a cold pain stimulation method: calibration, condition of interest (conventional placebo or educated placebo) and control. The investigators' main judgment criterion is be the difference in pain intensity experienced on the visual analog scale between the CPT control and the CPT under the condition of interest. This study will allow the investigators to rule on the non-inferiority of an educated open label placebo compared to a conventional placebo in the context of an acute painful stimulation.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

SINGLE

Enrollment

126

Conditions

Acute Pain

Interventions

Educational movie on placebo mechanisms : animated video, duration : 12 minutes. It will be followed by the CPTs : experimentally induced pain by keeping the non dominant hand in cold water (1° Celsius) for a limited time. The duration of immersion is personal and calibrated to be around to ensure that the intensity of pain will be homogeneous (around 7/10 on the visual analogue scale with no treatment)

Informative movie on hand washingOTHER

Animated video, duration : 11 minutes. It will be followed by the CPTs : experimentally induced pain by keeping the non dominant hand in cold water (1° Celsius) for a limited time. The duration of immersion is personal and calibrated to be around to ensure that the intensity of pain will be homogeneous (around 7/10 on the visual analogue scale with no treatment).

Eligibility

Sex: ALLMin age: 18 YearsMax age: 40 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria: * Person affiliated to Social Security * Informed consent, written and signed by the subject. Exclusion Criteria: * Persons referred to in Articles L1121-5 to L1121-8 of the Public Health Code (CSP), which corresponds to all protected persons: pregnant women, parturient women, nursing mothers, persons deprived of their liberty by judicial or administrative decision, persons subject to a legal protection measure, cannot be included in clinical trials. * Persons with a pathology against indicating the use of CPT experimentally induced pain : * Any pathologies affecting the venous, arterial or lymphatic system * Diabetes * Cardiac disorders * Asthma * Frostbite * Epilepsy * Arthritis * Lupus erythematosus * Allergy to Cremafluid® cream * Person with concomitant treatment that modifies sensitivity to pain, chronic or acute at the time of the experiment, such as analgesics, psychotropic drugs or anti-inflammatories.

Outcomes

Primary Outcomes

Pain intensity: Visual Analogue Scale (VAS)

Evaluated with a Visual Analogue Scale (VAS) from 0 to 100 mm, with a non inferiority margin at 10 mm and a standard deviation at 22 mm.

Time frame: At the end of the CPT procedure, within 30 seconds after the removal of the hand from the CPT cold water tank.

Secondary Outcomes

Anxiety respiratory frequency change

Evaluated thanks to the respiratory frequency collect with a PneumoTrace belt through LabChart software.

Time frame: During the CPT procedure

Anxiety blood pressure change

Evaluated thanks to the automatic blood pressure monitor (both systolic/diastolic blood pressure, heart rate)

Time frame: During the CPT procedure

Knowledge of placebo's mechanisms

Evaluated with a questionnaire made for this study with 17 questions about placebo mechanisms.

Time frame: At the beginning and end of the CPT procedures

Perception of the investigator

The perception of the investigator will be evaluated by a visual analogue scale "perception of the investigator".

Time frame: At the end of the study, when all CPT procedures have been carried out, within 10 minutes after the last immersion

The Perceived Awareness of the Research Hypothesis Scale questionnaire

Perception of the research hypothesis with the Rubin Questionnaire. Perceived Awareness of the Research Hypothesis " (PARH) wich is a scale of 4-item quantitative self-report method for measuring the potential influence of demand characteristics in research situations