The literature selection process and electronic search strategy is presented in the flow diagram Figure 1 and resulted in the following: PubMed (n=414), PsycINFO (n=61), Scopus (n=27), SSCI (n=2). There were 50 duplicates identified, which resulted in 454 exclusive titles reviewed by AR and RR.
A total number of 441 studies were excluded as they did not meet the inclusion criteria described previously.
Of 13 papers that appeared relevant for inclusion, four were excluded following full-text reading resulting in a total number of nine studies included in a qualitative synthesis.
Four inventory tools were identified through the nine included studies: The Impact of Event Scale (IES), the Impact of Event Scale-Revised (IES-R), the Clinical Administered PTSD Scale (CAPS), and the Post-Traumatic Stress Disorder Checklist (PCL), which are briefly described in the following. All these tools have been validated on a wide range of populations such as police officers, burn patients and motor vehicle accident survivors,[20][21][22].
The Impact of Event Scale and the Impact of Event Scale-Revised
The Impact of Event Scale (IES) and Impact of Event Scale-Revised (IES-R) were most frequently used on different populations exposed to various acute traumatic events (n=7). Both the IES and the IES-R have previously been validated and proven useful to predict PTSD,[23][24][20].
The original IES is a 15-item self-reported scale that assesses subjective distress caused by traumatic events, such as a resuscitation attempt. The scale is designed to assess the frequency of intrusive and avoidant stress symptoms with respect to a certain identified trauma, not related with traumatic symptoms in general. Intrusive symptoms refer to flashbacks to the event or dissociative reactions where it seems as if the trauma is reoccurring. Avoidant stress symptoms are expressed in questions that concern avoiding getting upset and trying not to think of the event.
The scale has been revised to the IES-R which contains seven additional items related to the hyperarousal symptoms of PTSD, such as anxiety and insomnia. These items were added to match the diagnose criteria for PTSD in the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders (DSM). It has been shown that high IES scores 1 week after a traumatic event predicts PTSD 6 months later with 92% sensitivity [25][26].
The maximum overall score possible in the IES-R is 12. The sum of the means of each subscale is recommended instead of raw sums. High levels of internal consistency and discriminative validity have been previously reported for the IES-R. A Japanese translation of the scale reported test-retest values and Rash et al described a high level of internal consistency among total and subscale scores (Crohnbach’s alpha 0.95). The convergent validity has been reported with consistent and high correlations between the IES-R and related measures of PTSD[27] [21] [28] [29].
A prospective observational study conducted by Zijlstra et al., evaluated the perceived short-term impact on psychological wellbeing of lay rescuers performing bystander CPR,[30]. Furthermore, they aimed to investigate the level of PTSD-related symptoms among bystanders 4-6 weeks after resuscitation attempts. This study was the only publication from the literature search measuring stress reactions with a validated inventory tool among citizen responders attempting resuscitation. The authors applied the IES to measure psychological symptoms of PTSD among the participants (n=189), by sending the scale to citizen responders four weeks after the resuscitation attempt. The authors found that 41% of the responders reported no/mild short-term psychological impact, 46% bearable impact and 24% severe impact on the IES. However, no of the citizen responders scored >26 (moderate or severe stress), 19% scored 9-25 (mild stress), and 81% scored 0-8 (no stress). None of the citizen responders reporting severe or bearable psychological impact on the short term scored more than mild stress levels on the IES (4-6 weeks after the event).
The IES has furthermore been validated to assess the psychological impact of a variety of traumas in a study by Van der Ploeg et al.,[24]. In this study, the authors evaluated the psychometric value of the Dutch version of the IES in three different samples of individuals who had experienced various traumatic stressors (work-related trauma, war-related trauma, and disasters). The authors found that the IES is a justified and valid instrument with a robust factor structure.
An earlier study by Zilberg et al. reported a detailed description of the IES and encouraged cross-validational data and analyses,[31]. The study concluded that the IES is a sensitive measure of change, suitable for intervention studies utilizing repeated measurements over time.
The IES-R has correspondingly to the IES been validated on a variety of different populations experiencing acute psychologically traumatic events. In a publication by Sveen et al., the authors studied the Swedish version of the IES-R and validated it against the DSM in a population of burn victims,[20]. The authors examined the ability of the scale to discriminate between individuals with and without PTSD. They found that participants with a positive PTSD diagnosis had higher scores on IES-R than those without a diagnosis. The results showed that the IES-R has good properties as a screening tool for the diagnosis of PTSD in patients with burns one year after injury. The IES-R has also proven useful in a study by Beck et al. based on a sample of motor vehicle accident survivors (n=182) who sought treatment for mental health problems following the injury,[21]. The authors examined the factor structure of the IES-R and its related psychometric features as well as the ability of the scale to differentiate between individuals with and without diagnosable PTSD. Based on their results, the authors suggested that the IES-R is not simply a measure of general distress but appears to have specific agreement in the assessment of PTSD symptomatology. The authors concluded that the scale had possibility to differentiate between individuals with and without PTSD although it was not developed as a diagnostic tool. The study suggests that the IES-R seems to be a solid measure of post-trauma phenomena that can enlarge related assessment approaches.
Another prospective study by Schütte et al. provides evidence that the IES-R is a suitable scale in predicting the development of stress symptoms and PTSD after experiencing an acute psychologically traumatic event,[22]. The authors investigated the predictors for the development of PTSD in 59 police officers who had experienced a traumatic incident during duty where the participants completed the IES-R immediately after the event and six months later.
The reliability and validity of the IES-R has moreover been examined in a Norwegian study by Eid et al.,[32]. The study was based on a non-clinical sample consisting of 311 undergraduate psychology students who were asked to review media reports from a tsunami disaster and were subsequently asked to rate their traumatic symptoms. The authors found that the Norwegian version of the IES-R has satisfactory psychometric properties with good reliability an accuracy in terms of detecting dimensions of PTSD-symptoms. The authors recommended to use the scale to measure traumatic symptoms with respect to a certain trauma in future studies. However, none of the students had been personally exposed to the tsunami but were only exposed through the media. The IES-R was administered to the students about three weeks after the disaster.
The CAPS - Clinical Administered PTSD Scale
The Clinical administered PTSD scale (CAPS) is known as the golden standard in PTSD assessment and has been revised several times. The scale is a 30-item structured clinical interview that in addition to the 17 PTSD symptoms includes items pertaining to the dissociative symptoms required for a diagnosis of Acute Stress Disorder. The newest version of the scale (CAPS-5) is a structured interview that assesses PTSD symptoms over the past week and makes current as well as lifetime diagnosis of PTSD,[33].
A longitudinal study by Bryant et al. was performed among survivors of traumatic injury,[34]. The study reported analyses that evaluated the capacity of Acute Stress Disorder in the initial month after trauma to predict a range of disorders including PTSD 12 months later. Acute Stress Disorder was assessed using the CAPS in the initial month after trauma. The authors found that 10% of the participants met criteria for Acute Stress Disorder at the initial assessment. After 12 months, 31% had a psychiatric disorder of which 10% met the criteria for PTSD. The study concluded that the majority of the trauma survivors who developed PTSD did not meet Acute Stress Disorder criteria in the initial month. Only a third of patients who did meet Acute Stress Disorder criteria developed PTSD. The acute stress disorder criteria measured by the CAPS has limited utility in identifying trauma-exposed individuals who are at risk for PTSD.
The PCL – Post-Traumatic Stress Disorder Checklist
The PCL is a psychometrically validated checklist developed to measure the 20 DSM-5 symptoms of PTSD. The scale is a self-reported measure and has various purposes, such as PTSD-screening, PTSD-diagnosing, and symptom change monitoring during and after treatment,[35][36]. A retrospective cohort study conducted by Waller et al investigated the association between numbers of stressful events and the severity of PTSD symptoms using the PCL. The authors aimed to explore if new stressful events trigger memories of previous events. A cohort consisting of 1,119 Australian military personnel deployed to the Middle East, was asked to report traumatic exposures associated with deployment. Scores on the PCL and stressful events were measured. The study found that personnel reporting more events had a higher mean PLC-score compared to those who reported no events. The study concluded that number of stressful events was significantly associated with more symptoms of PTSD,[37].