**1. Introduction**

#### **1.1. Victims of violent crimes**

Criminal acts are the most common traumatic events to which the general population is exposed [1]. According to Canada's General Social Survey [2], 6% of the population reported having been a victim of a violent crime in the last 12 months (e.g., sexual assault, armed robbery, and physical assault). Interpersonal violence represents a significant societal problem and has a detrimental impact on victims' health. Studies have shown that victims of violent crimes usually report important impairment to their functioning and psychological difficul‐ ties. Up to 20–21% subsequently develop posttraumatic stress disorder (PTSD) that might become chronic without intervention [3, 4], and this is all the more true for women [5, 6]. Indeed, lifetime prevalence rates of PTSD are twice as high in women as in men (10.4 vs. 5%) and women are four times more likely to develop PTSD when exposed to the same trauma. Thus, it appears important to identify victims at risk of developing subsequent PTSD, and to better understand gender differences regarding this risk.

The acute stress disorder (ASD) diagnosis was first introduced into the 4th edition of Diag‐ nostic and Statistical Manual of Mental Disorders (DSM‐IV) [7] to recognize stress reactions within the first month following a traumatic event and to identify victims at risk of developing PTSD [8]. To meet criteria for ASD in DSM‐IV, the individual must have experienced, wit‐ nessed, or been confronted to a traumatic event that triggered fear, helplessness, or horror (criteria A1 and A2). Moreover, the individual has to report symptoms from four clusters: three dissociative symptoms (criterion B), one reexperiencing symptom (criterion C), one avoidance symptom (criterion D), and one arousal symptom (criterion E). Symptoms have to cause distress or impairment (criterion F), and persist for at least 2 days, but no longer than 4 weeks (criterion G). However, in the recent DSM‐5 [9], no dissociative reaction is mandatory to establish an ASD diagnosis. According to Bryant [10], people who are at high risk for PTSD may not have met ASD criteria in the DSM‐IV because of the requirement of dissociative symptoms. Other studies suggest that the impact of dissociation may vanish on long‐term adjustment [11, 12]. In the DSM‐5, the individual must report nine symptoms out of 14, with onset or exacerbation occurring after the traumatic event. Symptoms for ASD in the DSM‐5 include intrusion (4), negative mood (1), dissociation (2), avoidance (2), and arousal (5). Hence, it appears relevant to comment on the DSM‐5 decisions in the hope of better detecting victims at risk for PTSD.

The predictive ability of ASD to predict PTSD is evaluated through the concept of predictive power. *Positive predictive power* refers to the probability of developing PTSD when an ASD symptom is present, while *negative predictive power* represents the probability of not developing PTSD when an ASD symptom is absent. To date, some studies have examined the positive and negative predictive power of ASD diagnosis, clusters, and/or symptoms on subsequent PTSD, and found inconsistent results [13]. A review has observed variability in the predictive ability of ASD, which could be explained by the diversity of trauma samples studied [14]. Most included studies focused on victims of major vehicle accidents (MVAs). Victims of major vehicle accidents and violent crimes differ in particular in terms of the interpersonal nature of the act. Victims of violence can struggle with feelings of injustice and betrayal as they attempt to come to terms with the fact that another human being is responsible for such reprehensive behavior [15]. A comparison study between MVA victims and violent crime victims revealed differences, such as lower positive predictive power in victims of violent crimes [8, 16]. In the literature, higher rates of PTSD are associated with intentionally inflicted violence [17]. Thus, these samples appear distinctive, which reinforces the importance of examining specific studies regarding victims of violent crimes.

#### **1.2. ASD diagnosis, clusters, and symptoms as predictors of PTSD**

**1. Introduction**

at risk for PTSD.

**1.1. Victims of violent crimes**

better understand gender differences regarding this risk.

132 A Multidimensional Approach to Post-Traumatic Stress Disorder - from Theory to Practice

Criminal acts are the most common traumatic events to which the general population is exposed [1]. According to Canada's General Social Survey [2], 6% of the population reported having been a victim of a violent crime in the last 12 months (e.g., sexual assault, armed robbery, and physical assault). Interpersonal violence represents a significant societal problem and has a detrimental impact on victims' health. Studies have shown that victims of violent crimes usually report important impairment to their functioning and psychological difficul‐ ties. Up to 20–21% subsequently develop posttraumatic stress disorder (PTSD) that might become chronic without intervention [3, 4], and this is all the more true for women [5, 6]. Indeed, lifetime prevalence rates of PTSD are twice as high in women as in men (10.4 vs. 5%) and women are four times more likely to develop PTSD when exposed to the same trauma. Thus, it appears important to identify victims at risk of developing subsequent PTSD, and to

The acute stress disorder (ASD) diagnosis was first introduced into the 4th edition of Diag‐ nostic and Statistical Manual of Mental Disorders (DSM‐IV) [7] to recognize stress reactions within the first month following a traumatic event and to identify victims at risk of developing PTSD [8]. To meet criteria for ASD in DSM‐IV, the individual must have experienced, wit‐ nessed, or been confronted to a traumatic event that triggered fear, helplessness, or horror (criteria A1 and A2). Moreover, the individual has to report symptoms from four clusters: three dissociative symptoms (criterion B), one reexperiencing symptom (criterion C), one avoidance symptom (criterion D), and one arousal symptom (criterion E). Symptoms have to cause distress or impairment (criterion F), and persist for at least 2 days, but no longer than 4 weeks (criterion G). However, in the recent DSM‐5 [9], no dissociative reaction is mandatory to establish an ASD diagnosis. According to Bryant [10], people who are at high risk for PTSD may not have met ASD criteria in the DSM‐IV because of the requirement of dissociative symptoms. Other studies suggest that the impact of dissociation may vanish on long‐term adjustment [11, 12]. In the DSM‐5, the individual must report nine symptoms out of 14, with onset or exacerbation occurring after the traumatic event. Symptoms for ASD in the DSM‐5 include intrusion (4), negative mood (1), dissociation (2), avoidance (2), and arousal (5). Hence, it appears relevant to comment on the DSM‐5 decisions in the hope of better detecting victims

The predictive ability of ASD to predict PTSD is evaluated through the concept of predictive power. *Positive predictive power* refers to the probability of developing PTSD when an ASD symptom is present, while *negative predictive power* represents the probability of not developing PTSD when an ASD symptom is absent. To date, some studies have examined the positive and negative predictive power of ASD diagnosis, clusters, and/or symptoms on subsequent PTSD, and found inconsistent results [13]. A review has observed variability in the predictive ability of ASD, which could be explained by the diversity of trauma samples studied [14]. Most included studies focused on victims of major vehicle accidents (MVAs). Victims of major vehicle accidents and violent crimes differ in particular in terms of the interpersonal nature of To date, four studies have examined the prevalence of ASD, the incidence of PTSD, and the predictive power of ASD diagnosis and clusters between 48 h and 6 weeks after a violent crime (i.e., physical assault, rape, and bank robbery) on PTSD 3–6 months later [4, 18–20]. Full ASD diagnosis was found in 12–59% of victims, and partial ASD (i.e., meeting all criteria except for dissociation symptoms) in 7–21%. Subsequently, 7–35% met full PTSD criteria and 22% for partial PTSD (i.e., at least one severe symptom in each symptom category plus reported impairment from these symptoms). The highest percentages were found in victims of rape, which were all women. ASD diagnosis had the best PTSD classification compared to each cluster (i.e., 62–90% of correct classification). For each cluster, negative predictive power was high, while positive predictive power was low. Two studies reported dissociation as the best predictive cluster (i.e., between 49 and 80% of correct classification). However, in these studies, ASD and PTSD symptoms were self-reported.

Regarding all types of trauma, only two studies (MVA and burn victims) have examined the predictive ability of ASD symptoms [8, 21, 22]. Results have shown that all symptoms were predictors, ranging from low to high positive predictive power (i.e., 0.12–1.00) and moderate to high negative predictive power (i.e., 0.78–1.00). Difede et al. [21] found that victims of burn injuries who developed PTSD reported recurrent images or thoughts, distress on exposure, avoidance of thoughts and activities, difficulty sleeping, irritability, poor concentration, motor restlessness, reduced awareness, and derealization more often than did individuals without PTSD. However, the generalization of these results to victims of violent crimes, who generally report more PTSD symptoms than victims of accidents, may be limited [23].

#### **1.3. Gender differences in the predictive power of ASD**

A study on victims of MVA showed that ASD was a better predictor of PTSD in women [24]. The authors suggested that this result was attributable to dissociation being a greater risk factor of PTSD in women. Moreover, positive predictive power was higher in women while negative predictive power was higher in men. Another study on MVA victims found that women were at greater risk for PTSD, and also more likely to report arousal symptoms, avoidance, and numbing symptoms and some reexperiencing symptoms [25]. In this study, women with dissociation were more at risk of developing PTSD. Thus, studies suggested a better predictive power of ASD for PTSD in women mainly because of gender differences in dissociative reactions.

Globally, studies on victims of violent crimes have supported the relevance of ASD diagnosis to predict PTSD. Predictive ability of partial ASD has only been documented in one study. Overall, all ASD clusters have shown high negative predictive power and low positive predictive power. However, it remains unclear which cluster better predicts PTSD diagnosis. The predictive power of each ASD symptom has not been examined in victims of violent crimes. Moreover, the differential predictive power of ASD clusters and symptoms according to gender has not been studied in these victims. Finally, previous studies have used self-report measures to evaluate ASD and PTSD, which suggests that responses were influenced by the victims' perceptions.

Moreover, it is well known that women are twice as likely as men to develop PTSD, but the reasons underlying this discrepancy remain unclear [5]. If ASD is considered a predictor of PTSD, it appears pertinent to determine to what extent ASD clusters and symptoms predict PTSD according to gender.
