Association Between Heat Pain Detection Threshold and Area of Secondary Hyperalgesia

Study Overview
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Brief Summary
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The purpose of this prospective study is to investigate how close Heat Pain Detection Threshold is associated with the area of secondary hyperalgesia, elicited by the clinical pain model Brief Thermal Sensitization. Furthermore we wish to investigate how close the clinical pain model: Pain during 1 min. heating of the skin (45 degrees celsius), and the psychological tests, Pain Catastrophizing Scale and Hospital Anxiety and Depression Scale are associated with the area of secondary hyperalgesia, elicited by the clinical pain model Brief Thermal Sensitization.

Detailed Description
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The study participants will be tested with 3 types of clinical pain models on two separate identical study days. A minimum of 7 days will separate the two study days, thus, the minimum length of the study is 7 days, but can be higher. The 3 types of pain conditioning consist of 1) Brief thermal sensitisation (BTS), 2) Heat pain detection threshold (HPDT), and pain during 1 min. thermal stimulation (p-TS. The order of the stimulations (HPDT and BTS) is randomised for each patient and each study day, by a random allocation sequence, computer-generated by Copenhagen Trial Unit and stored in sealed and opaque envelopes to secure adequate allocation concealment. p-TS is conducted subsequent to BTS and HPDT. The participants will complete the psychological tests Pain Catastrophizing Scale (PCS) and Hospital Anxiety and Depression Scale (HADS) in their private home prior to study day 1. The completed tests will be placed in opaque sealed envelopes to secure blinding of the investigator and outcome assessor.

Official Title
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To Determine the Degree of Association Between Heat Pain Detection Threshold and Area of Secondary Hyperalgesia Following Brief Thermal Sensitization in Healthy Male Volunteers

Conditions
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Healthy

Intervention / Treatment
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* Other: Brief thermal sensitization
* Other: Pain during 1 min. thermal stimulation
* Other: Heat pain detection threshold


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age >18 years and <35 years Speak and understand Danish Male gender Study participants who have understood and signed the informed consent No prescription medicine during the last 30 days. Exclusion Criteria: Study participants that cannot cooperate to the test. Study participants who have a weekly intake of >21 units of alcohol, or a have consumed >3 units of alcohol within 24 hours before experimental day. Study participants with a substance abuse, assessed by the investigator. Study participants, who have consumed analgesics less than 3 days before experimental day. Study participants, who have consumed antihistamines less than 48 hours before experimental day. Study participants, who have consumed antidepressant medication during the last 30 days before experimental day. Study participants with chronic pain. Study participants with neurological illnesses. Study participants with psychiatric diagnoses. Study participants with tattoos on the extremities. Study participants with eczema, wounds or sunburns on the sites of stimulation. Study participants with a Body Mass Index of >30 kg/m2 or <18 kg/m2

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 35 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Intervention Model: Single Group Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: Clinical pain models<br>Brief thermal sensitization. Heat pain detection threshold. Pain during 1 min. thermal stimulation | Other: Brief thermal sensitization<br>* A small area of the skin of the study participants are heated to 45 degree celsius for 3 minutes, followed by evaluation of secondary hyperalgesia.<br>* Other names: Clinical pain model;Other: Pain during 1 min. thermal stimulation<br>* A small area of the skin of the study participants are heated to 45 degrees celsius for 1 minute. During the 1 minute period, the study participant will continually report pain on an electronic visual analog scale.<br>* Other names: Clinical pain model;Other: Heat pain detection threshold<br>* The threshold for heat pain are evaluated by heating a small area of the study participants skin. When the study participant feels pain, the temperature (degrees celsius) is registered. 4 threshold measurements per session. Heat pain threshold is defined as the average temperature of the 4 measurements.<br>* Other names: Clinical pain model;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Size of the Area of secondary hyperalgesia following Brief thermal sensitization, evaluated by cm2, and heat pain detection threshold registered by degrees celsius. | How close is the Heat Pain Detection Threshold associated with the size of the area of secondary hyperalgesia induced by Brief thermal sensitization? Area of secondary hyperalgesia will be investigated on two separate study days separated with a minimum of 7 days. The association will be expressed in R2 and prediction intervals for the area of BTS given fixed values of HPDT. | 7 days | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pain during 1 min. thermal stimulation, evaluated by Area Under the Curve of the visual analog scale, 0-100 mm. | How close is the Visual analog scale (VAS)-AUC (area under the curve) following pain during 1 min. thermal stimulation associated with the size of the area of secondary hyperalgesia induced by Brief thermal sensitization? | Study day 1 and 2. A minimum of 7 days | 
| Pain during 1 min. thermal stimulation, evaluated by maximum on the visual analog scale, 0-100mm. | How close is the max. VAS-score following pain during 1 min. thermal stimulation associated with the size of the area of secondary hyperalgesia induced by Brief thermal sensitization? | Study day 1 and 2. A minimum of 7 days. | 
| Score of Pain Catastrophizing Scale | How close is the scores of Pain Catastrophizing Scale associated with the size of the area of secondary hyperalgesia induced by Brief thermal sensitization? | Study day 1 and 2. A minimum of 7 days. | 
| Score of Hospital Anxiety and Depression Scale | How close is the scores of Hospital Anxiety and Depression Scale associated with the size of the area of secondary hyperalgesia induced by Brief thermal sensitization? | Study day 1 and 2. A minimum of 7 days. | 
| Score of Subscales of Pain Catastrophizing Scale and Hospital Anxiety and Depression Scale. | How close are the subscales in the two psychological tests (PCS-rumination, PCS-magnification, PCS-helplessness, and HADS-Anxiety, HADS-Depression) associated with the size of the area of secondary hyperalgesia? | Study day 1 and 2. A minimum of 7 days. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Experimental pain, Men