An interventional study of Defusing and Psychological First Aid (PFA) in Acute Stress Disorder and Post Traumatic Stress Disorder PTSD, sponsored by Hospices Civils de Lyon. Not yet recruiting at 4 sites in France. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-09-30.
Sponsored by Hospices Civils de Lyon · Not applicable, Interventional, and Prevention
The exposure to a potential traumatic event (PTE) is common in the general population. This exposure may lead to psychiatric disorders such as acute stress disorder (ASD) and post-traumatic stress disorder (PTSD). Previous exposure to PTE is a well-known risk factor for ASD and PTSD. This may rely on the so called "kindling" which consists in a increasing sensitization of thememory circuits and emotional regulation through this previous and/or repeated exposure.
An early psychological intervention may prevent these diseases or at least decrease the symptoms and improve functional functioning. Defusing is an early and brief psychotherapeutic interview technique which aims at encouraging a victim exposed to a PTE to express her/his own experience concerning the PTE. Some preliminary results reported that defusing could alleviate the emotional distress induced by a PTE.
The PREDEKIT study hypothesizes that defusing prevents the sensitization (kindling) induced by a potentially traumatic event. This study is a prospective, randomized, controlled, multicenter trial with blinded outcome assessment. Participants can be included in the study they are exposed to a PTE and tif they can receive a defusing intervention in the very early phase following the PTE (first 24 hours). The test group will receive defusing while the control group will receive First Psychosocial Aid
Primary and secondary outcomes will assess emotional distress, intrusive symptoms, physiological outcomes relevant for the stress response (blood pressure, heart rate, electrodermal activity). The last evaluation takes place 1 month after the PTE
This is a multicenter, parallel-group, open-label controlled study with single blinded assessment.
Visit 1: Following a traumatic event (TE), the investigator team will be deployed to the scene (when indicated by the pre hospital emergency service) and will have the opportunity to meet the victims in the first 24h following the event. The investigators are mental health professionnals (nurses, psychologists ans psychiatrists) and all trained in defusing and briefed on the study protocol. One professional will be designated as the investigator leader for the intervention to manage the participants randomization into one of two possible arms:
FPA significantly differs from the defusing. This involves ensuring that basic needs are met: hunger, thirst, warmth/protection from cold, basic hygiene, and the ability to return home alone or with assistance. If needed, the caregiver links the victim to the appropriate resource For all study participants, several outcomes are measured at that timing
Visit 2 : taking place between Day 7 and Day 10 after the TE, in laboratory. It is composed of the following steps :
Baseline assessments
The narrative : the participant will be have to expose again the traumatic event (TE) that led to their inclusion in the study. Concerning the narrative, the interview with the investigator will be stantardized so that the narrative will last at least 10 minutes and reactivate the memory of the TE as high as possible.
Visit 3: taking place between Day 30 and Day 40 post TE by phone. It is composed of the following assessments :
Non inclusion Criteria :
Exclusion Criteria :
A brief (usually not longer than 20 minutes) structured interview conducted by a trained clinician (psychiatrist, psychologist, nurse in mental health) within the 24 hours following potential traumatic event (PTE). It focuses on narrative recall of the event (cognitive and emotional experience). It also commonly includes preliminary psychoeducation on common post-traumatic reactions, and support the activation of the resilience resources.
Behavioral: Defusing
Immediate support, based on World Health Organization (WHO) guidelines, dedicated to victims exposure to a collective disaster. It focuses on identifying the immediate needs (comfort, safety, medical or psychological care) of the victim in order to link him/her to the appropriate support/ressource. It does not include any psychotherapeutic intervention
Behavioral: Psychological First Aid (PFA)
A brief (usually not longer than 20 minutes) structured interview conducted by a trained clinician (psychiatrist, psychologist, nurse in mental health) within the 24 hours following potential traumatic event (PTE). It focuses on narrative recall of the event (cognitive and emotional experience). It also commonly includes preliminary psychoeducation on common post-traumatic reactions, and support the activation of the resilience resources
PFA is an immediate support, based on World Health Organization (WHO) guidelines, dedicated to victims exposure to a collective disaster. It focuses on identifying the immediate needs (comfort, safety, medical or psychological care) of the victim in order to link him/her to the appropriate support/ressource. It does not include any psychotherapeutic intervention In addition, the participants are informed on the available psychotraumatism focused psychological care which can be delivered after the Visit 2.
Level of emotional distress at reminding/reactivation of the traumatic memory
Emotional distress is self-reported on an 11-point Visual Analogue Scale (VAS) ranging from 0 ("no distress") to 10 ("extreme distress"). The assessment is performed following a triggered recall of the traumatic memory at Visit 2 (Days 7-10) and compared to baseline (inclusion).
Time frame: From Baseline (Day 0) to Visit 2 (Days 7-10 post-event)
Ruminative thoughts and intrusive symptoms during the initial follow-up
Daily scores recorded twice daily (midday and bedtime) on a tracking log for 7 consecutive days following the potential traumatic event. Includes emotional distress (VAS 0-10) and frequency/severity of intrusive psychotraumatic symptoms (visual intrusive symptoms, ruminations, and nightmares, rated 0-4).
Time frame: Twice daily (midday and evening) from Day 1 to Visit 2
Physiological Stress Responses During Trauma Recall
Blood pressure assessed before, during, and after the narrative recall of the traumatic memory at Visit 2 (Days 7-10 after the PTE)
Time frame: At Visit 2 (Days 7-10 post-event)
Physiological Stress Responses During Trauma Recall
Heart rate assessed before, during, and after the narrative recall of the traumatic memory at Visit 2 (Days 7-10 after the PTE)
Time frame: At Visit 2 (Days 7-10 post-event)
Physiological Stress Responses During Trauma Recall
Electrodermal activity (EDA) assessed before, during, and after the narrative recall of the traumatic memory at Visit 2 (Days 7-10 after the PTE)
Time frame: At Visit 2 (Days 7-10 post-event)
Correlations between emotional distress during the recall of the traumatic memory and risk factors for PTSD.
Correlation Scores between post-recall the variation of the emotional distress score (VAS ; from baseline to Visit 2) and the following psychometric scales: Peritraumatic Dissociative Experiences Questionnaire (PDEQ, score range 9-45), Peritraumatic Distress Inventory (PDI, score range 0-52), Life Events Checklist for DSM-5 (LEC-5), and Impact of Event Scale-Revised (IES-R, score range 0-88).
Time frame: At Baseline (Day 0) and Visit 2 (Days 7-10 post-event)
PTSD symptoms
Post-Traumatic Stress Disorder Checklist for DSM-5 (PCL-5) score assessed via telephone interview. Il includes 20 items rated on a 5-point Likert scale (total score range 0-80), higher scores indicating greater symptom severity.
Time frame: At Visit 3 (Days 30-40 post-event)
Assessment of Social Support Level
Social Provisions Scale 10-item version (SPS-10) administered via telephone interview. Items rated on a 4-point scale (total score range 10-40), higher scores reflecting greater perceived social support.
Time frame: At Visit 3 (Days 30-40 post-event)
Implementation of Psychological Follow-Up Care
Proportion of participants who initiated ongoing professional psychological care/therapy at 1 month post-event.
Time frame: At Visit 3 (Days 30-40 post-event)
Plan to share: Yes — Every raw data relevant for the publication will be available for sharing
Supporting information: Study protocol
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Stress Disorders, Traumatic, Acute→
Hospices Civils de Lyon