Psychological Trauma: Theory, Research, Practice, and Policy 2015, Vol. 7, No. 3, 212–221

© 2015 American Psychological Association 1942-9681/15/$12.00 http://dx.doi.org/10.1037/a0038780

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Predictors of Posttraumatic Stress Disorder Among Police Officers: A Prospective Study André Marchand

Céline Nadeau and Dominic Beaulieu-Prévost

Université du Québec a` Montréal and Centre de Recherche de l’Institut Universitaire en santé mentale de Montréal, Montréal, Québec, Canada

Université du Québec a` Montréal

Richard Boyer

Mélissa Martin

Centre de Recherche de l’Institut Universitaire en santé mentale de Montréal, Montréal, Québec, Canada

Université du Québec a` Montréal

This prospective study examined risk and protective factors in the development of posttraumatic stress disorder (PTSD) in a sample of 83 police officers. Structured interviews were conducted in order to assess the most recent work-related traumatic event and establish diagnoses of acute stress disorder (ASD) and full or partial PTSD. Police officers were assessed between 5 and 15 days, and at 1 month, 3 months, and 12 months after the event. They also completed self-administered questionnaires assessing several potential predictors. Predictive analyses about the onset of PTSD were based on a 4-step nested random-effect linear regression. Overall, results showed that the modulation of PTSD symptomatology was associated with some pretraumatic (i.e., emotional coping strategies and number of children), peritraumatic (i.e., physical and emotional reactions and dissociation), and posttraumatic factors (i.e., ASD, depression symptoms, and seeking psychological help at the employee assistance program and at the police union between the event and Time 1). Clinical implications of these findings are discussed and key directions for future studies are proposed. Keywords: posttraumatic stress disorder (PTSD), police, risk factor, protective factor, prospective study Supplemental materials: http://dx.doi.org/10.1037/a0038780.supp

velop ASD or PTSD (King, Vogt, & King, 2004). Studies have identified a series of risk and protective factors involved in the modulation of posttraumatic reactions. These can be classified into three categories: pretraumatic, peritraumatic, and posttraumatic. Martin, Germain, and Marchand (2006) offer a detailed review of such factors, but only an overview of the main findings with police officers is presented here.

Due to the nature of their work, police officers encounter frequent exposure to unpredictable incidents that pose a threat to their life or their physical integrity (e.g., road accidents, gunfire, suicides, and homicides). These potentially traumatic events can generate major repercussions on their psychosocial and occupational functioning. They can even lead to the development of acute stress disorder (ASD) or posttraumatic stress disorder (PTSD; Carlier, 1999; McNally & Solomon, 1999). However, not all police officers exposed to traumatic events will subsequently de-

Pretraumatic Predictors Studies among police officers have identified several pretraumatic predictors of PTSD. In summary, recent investigations have found that cumulative exposure to duty-related critical incidents, occupational stressors, and a greater exposure to traumatic events at work during the past year predispose to the development of posttraumatic reactions (Friedman & Higson-Smith, 2003; Liberman et al., 2002; Violanti & Gehrke, 2004). Other studies have revealed that limited work experience increased the likelihood of developing PTSD for junior police officers (Hodgins, Creamer, & Bell, 2001; Marmar et al., 2006). The impact of past personal traumas also appears to be a significant predictor (Gehrke & Violanti, 2004; Pole, 2008). Moreover, the presence of family psychiatric history (i.e., mood, anxiety and substance abuse disorders) was identified as a vulnerability factor for experiencing greater peritraumatic distress to critical incident exposure, which,

This article was published Online First March 16, 2015. André Marchand, Department of Psychology, Université du Québec a` Montréal, and Centre de Recherche de l’Institut Universitaire en santé mentale de Montréal, Montréal, Québec, Canada; Céline Nadeau, Department of Psychology, Université du Québec a` Montréal; Dominic BeaulieuPrévost, Department of Sexology, Université du Québec a` Montréal; Richard Boyer, Centre de Recherche de l’Institut Universitaire en santé mentale de Montréal; Mélissa Martin, Department of Psychology, Université du Québec a` Montréal. This research was supported by grants from Institut de recherche RobertSauvé en santé et en sécurité du travail. Correspondence concerning this article should be addressed to André Marchand, Department of Psychology, Université du Québec a` Montréal, P. O. Box 8888, Succ. Centre-Ville, Montréal (Québec), H3C 3P8 Canada. E-mail: [email protected] 212

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PREDICTORS OF PTSD IN POLICE OFFICERS

in turn, increased the risk of developing PTSD (Inslicht et al., 2010). Women police officers seem to have the same risk of developing PTSD after a traumatic event than their male counterparts (Darensburg et al., 2006; Pole et al., 2001). Neurotic personality as well as trait dissociation are associated with greater PTSD symptoms among police officers (Haisch & Meyers, 2004; Marmar et al., 2006; McCaslin et al., 2008). Those who have difficulties in expressing their emotions are more likely to develop posttraumatic reactions (Carlier, Lamberts, & Gersons, 1997; Meffert et al., 2008). The tendency to fear anxiety-related symptoms is also a risk factor for PTSD (Asmundson & Stapleton, 2008). Lastly, hypersensitivity to threat and a slower habituation process were found to prospectively predict PTSD symptom severity in police recruits (Pole et al., 2009). Prior experience of successful field operation and adequate training to react to stressful situations were reported by some studies as preventing posttraumatic reactions (Marmar et al., 2006; Perrin et al., 2007), but were not confirmed by others (Alexander & Wells, 1991; Carlier et al., 1997). Furthermore, personality hardiness was found to be negatively associated with PTSD symptoms in female police officers (Andrew et al., 2008; Martin, Marchand, Boyer, & Martin, 2009). As for coping strategies, results remain unclear as to whether emotion- or problem-focused coping strategies are beneficial for police officers (LeBlanc, Regehr, Jelley, & Barath, 2008; Marmar et al., 2006).

Peritraumatic Predictors Peritraumatic experiences such as dissociation, physical and emotional reactions during trauma, a threat to one’s partner’s life or physical integrity, severity of exposure, as well as exposure to death constitute risk factors in the development of PTSD among police officers (Hodgins et al., 2001; Inslicht et al., 2010; Marmar et al., 2006; Martin et al., 2009; McCaslin et al., 2006, 2008; Perrin et al., 2007; Pole et al., 2001). In addition, one study has found that police officers carrying out unusual tasks during a critical event (e.g., rescuing or recovering work at the World Trade Center sites, working outside one’s area of expertise, working for prolonged time) were more at risk of developing PTSD (Perrin et al., 2007). The only study, to our knowledge, that assessed peritraumatic protective factors reported that police officers who received support from their colleagues during or immediately after a traumatic event developed less PTSD symptoms (Martin et al., 2009).

Posttraumatic Predictors Studies have outlined several posttraumatic factors that predict PTSD among police officers, such as short periods of time allocated by the employer to recover from the event, dissatisfaction with organizational support, or lack of social support outside of police work (Carlier et al., 1997). Incident-related physical injuries, depressive symptoms, as well as subsequent negative life events have also been identified as risk factors (Asmundson & Stapleton, 2008; Maguen et al., 2009). Many studies have shown that using avoidance-based strategies to cope with traumatic events is related to greater posttraumatic symptoms (Haisch & Meyers, 2004; LeBlanc et al., 2008; Marmar et al., 2006). Furthermore, psychological debriefing was found either to have no impact (Stephens, 1997) or to increase PTSD symptoms (Carlier, Lam-

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berts, Van Uchelen, & Gersons, 1998; Carlier, Voerman, & Gersons, 2000). For police officers, higher perceived availability of social support (Friedman & Higson-Smith, 2003; McCaslin et al., 2006) and greater satisfaction with the support received (Wilson, Poola, & Trew, 1997) have been associated with lower posttraumatic symptomatology. A positive attitude from coworkers and supervisors about expressing emotions, and ease in talking about trauma at work, were also associated with fewer PTSD symptoms (Stephens & Long, 2000). A sense of coherence is linked to reduced PTSD symptomatology as well (Friedman & Higson-Smith, 2003). To sum up, a significant amount of work has been done in the field of police psychological trauma, but some findings have been inconclusive. There is currently no consensus about the significance and predictive power of certain factors that influence PTSD symptoms. These ambiguous findings can be explained by the many methodological shortcomings in PTSD research, such as the lack of rigor in many studies, the presence of confounding variables, and the retrospective aspect of most studies. All these problems significantly limit the interpretation of the associations between predictors and PTSD. In addition, the number of studies on this topic is limited and many aspects have yet to be explored.

Objectives The first purpose of this research project aims to address the lack of prospective studies in the police environment and the existence of methodological shortcomings in the current literature. The second purpose is to expand our knowledge about the predictors of PTSD among police officers. The main objective was to identify the predictors of the development of PTSD following a work-related traumatic event among police officers using a longitudinal design. More specifically, this study assessed the risk factors that increase police officers’ vulnerability to developing PTSD, as well as the protective factors that help them cope after a traumatic event.

Method Participants and Procedure The main inclusion criterion to participate in this study was having recently been exposed to a traumatic event as defined by Criteria A for PTSD in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev.; DSMIV-TR; American Psychiatric Association, 2000). Exclusion criteria were being in a psychotic state, having an organic mental disorder, and having suicidal ideation. Written informed consent was obtained from all participants, and an institutional review board approved the study. Eighty-nine participants were initially contacted. Six were excluded after the initial assessment because they did not meet the inclusion criteria. Eighty-three participants took part in the study (i.e., 63 men and 20 women). Two of them withdrew from the study at 3 months (Time 3 [T3]), and five did so at 12 months (Time 4 [T4]; e.g., moved, lack of time, or loss of interest). All of the participants were active police officers from the police service of a major Canadian city with a mean of 8.6 years (SD ⫽ 7.3) of experience within the police service. They had a mean age of 33

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Table 1 Sociodemographic Characteristics of Police Officers Exposed to a Traumatic Event (n ⫽ 83)

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Sociodemographic data Gender Male Female Age at time of study Marital status Single In a relationship Separated or divorced Number of children One Two Three or more Number of years of education Ethnic origin Caucasian Ethnic minority Afro-Canadian Asian Hispanic Number of years of experience Number of hours worked per week

%

M (SD)

76 24 32.6 (7.7) 39 54 7 11 19 11 15.6 (1.9) 92 8 5 2 1 8.6 (7.3) 35.4 (3.2)

years (SD ⫽ 7.7), an average of 16 years of education (SD ⫽ 1.9), and 54% were married or in a relationship (see Table 1). Police officers were informed of the study through articles published in police union and police department newsletters. The project was also presented on numerous occasions to senior managers of various divisions of the police department—to the police employee assistance program’s officials and the labor management joint committee, which is composed of representatives of the union and of the organization. Overall, most referrals came from police officers themselves (e.g., participants, supervisors, lieutenants, and commanders), from the corporate operations division, and from the EAP. Potential participants were first screened over the phone and then assessed in person by a trained research assistant using a clinical standardized interview at the police station at four points in time: 5 to 15 days (M ⫽ 14.7, SD ⫽ 5.9) after the traumatic event (Time 1 [T1]), and 1 month (Time 2 [T2]), 3 months (T3), and 12 months (T4) following the event. Participants also filled out questionnaires after each interview.

Type of Trauma The traumatic events experienced by participants were categorized as shootings (40%), riots (14%), family drama involving death or serious injuries of children (14%), car chases (10%), deadly road accidents (4%), and other (18%). The emotion reported most frequently by participants concerning the event was helplessness (80%), followed by intense fear (59%) and horror (21%).

Measures Measures are presented sequentially for outcomes, pretraumatic factors, peritraumatic factors, and early posttraumatic factors (5 to

15 days after the event). The French versions of the questionnaires were used and all of them presented good psychometric properties. Outcomes. The presence or absence of PTSD was assessed at T2, T3, and T4 with the Structured Clinical Interview for DSM–IV Axis I Disorders (SCID-I; First, Spitzer, Gibbon, & Williams, 1996). Most studies about the psychometric properties of the SCID-I were conducted using the previous version (SCID-I, DSM– III–R; American Psychiatric Association, 1987). Nonetheless, the properties of the older version also apply to the current one (SCID-I, DSM–IV–TR; American Psychiatric Association, 2000), as the modules are virtually identical (Roger, 2001). The earlier version had good concomitant validity with clinician judgment (␬ ⫽ 0.69; Hovens et al., 1992), as well as good convergent validity with other PTSD measurements, such as the Impact of Event Scale (Solomon et al., 1993). For interrater reliability, kappa values of 0.87 (Kulka et al., 1990) and 0.77 (Skre, Onstad, Torgersen, & Kringlen, 1991) have been reported. The few studies that have been done with the current version of the SCID-I have reported reliability coefficients comparable with, if not greater than, those of the earlier version (Roger, 2001). A diagnosis of partial PTSD was assigned when a participant did not have enough symptoms to qualify for full PTSD (i.e., had at least one Criterion B, C, and D symptom or at least one Criterion B and two Criterion D symptoms; Schnurr, Lunney, & Sengupta, 2004). In addition, the intensity of PTSD symptoms was assessed with the total score of the Modified PTSD Symptom Scale (MPSS-SR; Falsetti, Resnick, Resick, & Kilpatrick, 1993), a 17-item selfreport questionnaire measuring the frequency and severity of posttraumatic symptoms in the last 2 weeks. Scores range from 0 to 102. The English version had an internal consistency of 0.91, specificity of 83.8%, and concurrent validity of 0.92 with the SCID. The French version was validated in Quebec with a clinical sample (Guay, Marchand, Iucci, & Martin, 2002), and possessed excellent internal consistency (Cronbach’s ␣ ⫽ .92) and temporal stability (r ⫽ .98). The internal consistency in this study was excellent (Cronbach’s ␣ ⫽ .96). Pretraumatic factors. Five categories of pretraumatic factors were assessed: sociodemographic characteristics, work-related information, trauma history, mental health, and psychological traits (i.e., coping strategies, self-efficacy, and psychological hardiness). A questionnaire was created by the current research team to gather information about sociodemographic characteristics (age, gender, education, marital status, number of children, and ethnic background) and work-related variables (job position, weekly hours worked, day/night shifts, and years of experience). Trauma history was assessed by counting the number of traumatic events reported on the Life Event Checklist of the ClinicianAdministered PTSD Scale (Blake et al., 1995). The checklist assesses exposure to 16 events known to potentially result in PTSD, and has an additional open-ended item allowing for the addition of any unlisted event. The French version of the questionnaire was validated with Quebec students (Blake et al., 1995). The checklist had good test–retest reliability (r ⫽ .97). Internal consistency was not assessed for this variable because it is not considered a relevant characteristic for life events scales. Mental health was assessed by counting the number of psychiatric disorders identified in the SCID-I interview. The participants were also asked whether or not they consulted a medical or paramedical professional in the last 3 months.

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PREDICTORS OF PTSD IN POLICE OFFICERS

Coping strategies were assessed with the Coping Inventory for Stressful Situations (CISS; Endler & Parker, 1990), a 48-item self-report inventory measuring task, emotion-, and avoidanceoriented components of coping (16 items/component). A study of the French version of the CISS has shown that the three subscales are relatively independent constructs and that each subscale had a good internal consistency, with Cronbach’s alphas between 0.83 and 0.87 (Rolland, 1994). Each subscale is rated from 16 to 80. The internal consistencies in this study were excellent (Cronbach’s ␣ between 0.89 and 0.92). Self-efficacy was assessed with the Self-Efficacy Scale (Sherer et al., 1982), a self-report measure designed to assess feelings of self-efficacy related to specific situations or behaviors. Its 23 items can be divided into two distinct subscales: general (17 items) and social (six items). The instrument had good internal consistency, with a Cronbach’s alpha of 0.86 for the general subscale, and 0.71 for the social subscale. No test–retest reliability was reported. The internal consistency in this study was good for the general subscale (Cronbach’s ␣ ⫽ .74) and poor for the social subscale (Cronbach’s ␣ ⫽ .49). Psychological hardiness was assessed with the Short Hardiness Scale (Bartone, 1995), a 15-item questionnaire that measures three dimensions of psychological hardiness: commitment, control, and challenge. The French version was validated with adults from Quebec (Dufour-Pineault, 1997). The Cronbach’s alpha was 0.66 for the overall assessment, whereas the corresponding coefficients for the commitment, control and challenge subscales were 0.48, 0.48, and 0.69, respectively. Test–retest reliability was 0.71. The internal consistencies in this study were 0.65, 0.55, and 0.64, respectively. Peritraumatic factors. Three categories of peritraumatic factors were assessed: duration (self-reported time in minutes), trauma severity, and peritraumatic reactions (i.e., dissociative experiences, emotional reactions and physical reactions). Trauma severity was assessed with the Trauma Severity Questionnaire, which measures, with 24 items, the objective and subjective dimensions of the traumatic event, such as the nature and duration of the event, the uncontrollable character of the event, and more (Martin, Marchand, & Boyer, 2003). This is a specific questionnaire developed by the current research team. No validation has been carried out. Dissociative experiences were assessed with the self-report version of the Peritraumatic Dissociative Experiences Questionnaire (PDEQ; Marmar, Weiss, & Metzler, 1997), a 10-item measure of dissociative reactions at the time of trauma, including confusion, depersonalization, derealization, time distortion, and out-of-body experience. The instrument has good reliability and validity coefficients (Tichenor, Marmar, Weiss, Metzler, & Ronfeldt, 1996). It also has good convergent, discriminant, and predictive validity (Marmar et al., 1994). The French version of the questionnaire was validated with a student population (Martin & Marchand, 2000) and showed psychometric properties equivalent to the English version (Cronbach’s ␣ of 0.85 and test–retest reliability of 0.88). The internal consistency in this study was good (Cronbach’s ␣ ⫽ .86). Emotional and physical reactions were assessed with the emotional and physical subscales of the Initial Subjective Reaction (ISR) Scale of the Potential Stressful Events Interview (Falsetti, Resnick, Kilpatrick, & Freedy, 1994). The emotional subscale

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(ISR-E) uses 15 items, with a 4-point Likert scale, to measure the intensity of various emotional reactions to the event (e.g., fear, confusion, sadness, shame, surprise, anger). Scores range from 15 to 60. The physical subscale (ISR-P) uses 10 items to measure the intensity of various reactions to the event related to panic attacks (e.g., sweating, breathlessness, dizziness, heart palpitations, hot flushes). Scores range from 10 to 40. Cronbach’s alpha varied between 0.62 and 0.79 for the ISR-E, and equaled 0.86 for the ISR-P, and the convergent validity, discriminant validity, and reliability of the questionnaire were satisfactory (Bernat, Ronfeldt, Calhoun, & Arias, 1998; Falsetti et al., 1994). The internal consistencies in this study were good (Cronbach’s ␣ of 0.83 and 0.71, respectively). In addition, the SCID-I interview was used to assess whether or not the participants experienced during the event at least one of (a) the emotions associated with a PTSD diagnosis (i.e., intense fear, horror and/or helplessness), or (b) other negative emotions (i.e., anger, shame and/or guilt) typically associated with traumatic events. Early posttraumatic factors. Three categories of early posttraumatic factors were assessed: job-related consequences, perceived social support, and early posttraumatic symptoms (i.e., ASD and depressive symptoms). A questionnaire was created by the team to assess the following job-related consequences between the event and T1 (5 to 15 days after the event): the negative impact of the media coverage of the event, satisfaction toward support offered at the job, and whether or not six types of events happened following the traumatic event (i.e., being offered a psychological debriefing, being given days off or work accommodations, and seeking help at the EAP, at their union and/or at the internal volunteer helpline). Each variable was assessed with a single question. Perceived social support was assessed with the Perceived Support Inventory (Guay & Miller, 2000), a self-report measure consisting of two subscales regarding the perceived behavior of the closest significant other: (a) an 11-item measure of perceived positive social support, and (b) a 13-item measure of perceived negative social interactions. The French version had a very good internal consistency (0.87), and a coefficient of convergent validity with the Social Provisions Scale of r ⫽ .44 (Guay & Miller, 2000). The internal consistency in this study was excellent for the positive scale (Cronbach’s ␣ ⫽ .90) and good for the negative scale (Cronbach’s ␣ ⫽ .85). The number of symptoms associated with ASD was assessed with a SCID-I interview. Depressive symptoms were assessed with the Beck Depression Inventory–II (Beck, Steer, & Brown, 1996), a 21-item questionnaire measuring depressive symptoms for the past 2 weeks. A psychometric study with French-speaking university students (Bourque & Beaudette, 1982) revealed good concurrent validity with other measures of depression. The internal consistency in this study was excellent (Cronbach’s ␣ ⫽ .93).

Design and Data Analyses The analyses were performed using Stata 13, and a Type I error of 0.05 was selected. Both the bivariate and the predictive analyses of the longitudinal data were computed using nested random-effect models (i.e., the xtreg function on Stata). Multiple imputations were used to deal with missing values.

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For the analyses, predictors were grouped into (a) sociodemographic and pretraumatic variables, (b) peritraumatic variables, and (c) posttraumatic variables. Predictive analyses for PTSD symptoms were carried out in two phases. First, bivariate analyses were conducted between each of the predictors and the severity of PTSD symptoms. Predictive models of the severity of PTSD symptoms were then carried out. Variables that were not statistically correlated with the dependent variables in the first phase were excluded. Variables with a distribution that could not be approximated by a Gaussian curve were transformed, and analyses were also performed on the transformed data. Only the analyses carried out on the original data are presented, but all tests remained significant when performed on the transformed data. To predict the severity of PTSD symptoms as measured on the MPSS-SR after 1 month (T2), 3 months (T3), and 12 months (T4), a four-step nested random-effect linear regression was carried out. Step 1 only included the time of measurement as an independent variable, Step 2 included pretraumatic and sociodemographic variables, Step 3 included peritraumatic variables, and Step 4 included posttraumatic variables. Models were simplified at each step by removing variables with a statistically nonsignificant contribution. In order for the four successive step models to be nested in one another, variables introduced in a preceding step were retained even if they became statistically nonsignificant afterward. The additional contribution of each nested model was assessed with a likelihood ratio test. Each contributing variable was also tested in interaction with the time of measurement to identify potential differences in effect size between T2, T3, and T4.

Results Incidence of ASD and PTSD Within the first month following the trauma, 9% of the police officers developed ASD. Four of them subsequently developed PTSD, either full (n ⫽ 2) or partial (n ⫽ 2). At T2, 3% of all the participants met criteria for full PTSD 1 month after the traumatic event, whereas 9% presented partial PTSD. At T3 and T4 (3 months and 1 year following the event), 4% of participants met criteria for partial PTSD. Rates for full or partial PTSD decreased from 12% at one month to 4% subsequently

Predictors of PTSD Symptoms Predictive analyses were carried out on the intensity of PTSD symptoms (MPSS-SR) rather than on the presence or absence of a diagnosis due to the very low number of cases with a diagnosis (e.g., no full diagnosis and only a few partial diagnoses after T2). Four participants never filled out the MPSS-SR and had missing data on many predictors. As recommended for multiple imputation (von Hippel, 2007), the four cases with missing values for the dependent variable were removed from the predictive analyses after imputation. Overall, less than 5% of the data was imputed. Bivariate analyses between predictors and the severity of symptoms are presented in Table 2. The complete matrix of pairwise correlations between all the variables is available in Table S1 of the online supplemental materials. At Step 1 of the nested model, the severity of the PTSD symptoms was shown to be statistically higher at T2, and not

Table 2 Standardized Regression Coefficients (Beta) Between Predictors and Scores on the MPSS-SR (N ⫽ 79) Variable (scale range) Pretraumatic factors Emotion-oriented coping strategies (16–80) Self-efficacy (12–48) Number of children For men For women Peritraumatic factors Duration of the event (min.) Initial physical reactions–ISR-P (10–40) Initial emotional reactions–ISR-E (15–60) Dissociation–PDEQ (10–50) Early posttraumatic factors (5–15 days after the event) Number of clinical symptoms of ASD at T1 (0–18) BDI-II at T1 (0–63) Negative support between event and T1 (12–48) Positive support between event and T1 (11–44) Negative impact of media coverage between event and T1 (1–5) Days off because of the event before T1 Sought help at the police union between event and T1 Sought psychological help at the EAP between event and T1

M/%

Beta

26.7 21.8

0.47ⴱⴱⴱ ⫺0.24ⴱ

0.9 0.7

0.31ⴱⴱ ⫺0.21a

87.9 14.2 24.8 15.2

0.26ⴱⴱ 0.37ⴱⴱⴱ 0.44ⴱⴱⴱ 0.40ⴱⴱⴱ

2.8 3.8 13.8 30.5 1.8 37.3% 30.4% 20.3%

0.55ⴱⴱⴱ 0.59ⴱⴱⴱ 0.22ⴱ 0.23ⴱ 0.36ⴱⴱⴱ 0.23ⴱ 0.33ⴱⴱⴱ 0.36ⴱⴱⴱ

Note. ASD ⫽ acute stress disorder; BDI-II ⫽ Beck Depression Inventory II; ISR-E ⫽ Initial subjective reaction - Emotional; ISR-P ⫽ Initial subjective reaction - Physical; PDEQ ⫽ Peritraumatic Dissociative Experiences Questionnaire; Time 1 ⫽ T1. a Nonsignificant, p ⬎ 0.05. ⴱ p ⬍ .05. ⴱⴱ p ⬍ .01. ⴱⴱⴱ p ⬍ .001.

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PREDICTORS OF PTSD IN POLICE OFFICERS

statistically different between T3 and T4. The time variable was thus simplified to a dichotomous variable (T2 vs. T3 and T4) for modeling purposes. At Step 2 (pretraumatic variables), the number of children was found to be statistically associated with more severe symptoms, but only for men and only after one child. The variable was thus simplified to only account for additional children (over one) for men. Emotion-oriented coping was also found to be associated with more severe PTSD symptoms. At Step 3 (peritraumatic variables), the three scales assessing peritraumatic reactions (ISR-E, ISR-P, and PDEQ) were found to be highly correlated predictors. To avoid problems of multicollinearity, a composite indicator of peritraumatic reaction was created to replace these three predictors. A principal component analysis was done on the three variables and the indicator was created by extracting the first component. The first component explained 76% of the variance. The resulting indicator was a better predictor than any of the original variables, and had correlations between 0.84 and 0.90 with them. The indicator of peritraumatic reaction was also found to interact with time and to be more strongly associated with PTSD symptoms at T2 than afterward. To facilitate interpretation of the indicator of peritraumatic reaction, its mean was first calibrated to have a minimal value of zero (corresponding to no symptoms). In addition, its variance was adjusted so that the unstandardized coefficient of the PDEQ equals 1 when the three original variables are used in a linear regression to predict the indicator. The consequence of this last transformation is that a one-unit change on this PDEQ-adjusted indicator can be interpreted as the equivalent of a one-unit change on the PDEQ, while controlling for the two other variables. The indicator was also translated into an ISR-E-adjusted version and an ISR-Padjusted version to allow for an interpretation of the indicators

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with the original scales in mind. The analyses were first done with the PDEQ-adjusted indicator, but were rerun with the other versions to calculate the coefficients of the indicator in the units of each original scale. At Step 4 (posttraumatic variables at T1), the two measures of posttraumatic symptomatology (number of ASD symptoms and BDI) were also found to be highly correlated predictors. A composite symptom indicator was thus created following the procedure explained in Step 3. The first component explained 92% of the variance. The resulting indicator was a better predictor than the original variables and was correlated at 0.96 with both of them. The analyses were first done with the ASD-adjusted indicator and were subsequently rerun with the BDI-adjusted version. The indicator of posttraumatic symptoms at T1 was also found to interact with time and to be more strongly associated with PTSD symptoms at T2 than afterward. Finally, the variable seeking help at the EAP and at the police union were found to statistically contribute to the model, but only in interaction (i.e., for those who sought help both at the EAP and the police union). The variables were thus simplified into a single dichotomous variable assessing whether or not help was sought at both places. Each step contributed a statistically significant amount of additional explained variance, with totals of explained variance at the pretraumatic, peritraumatic, and posttraumatic levels being, respectively, 32%, 46%, and 64%. The complete nested model is shown in Table 3.

Interpretation of the Predictive Model for PTSD Symptoms As shown at the first step of the predictive model, there was a statistically significant decrease in PTSD symptoms between T2 (1

Table 3 Predictive Model of PTSD Symptoms at T2, T3, and T4 (N ⫽ 79) Included variables Constant (baseline MPSS score) For T2 For T3 and T4 Additional children (men only) Emotion-oriented coping Peritraumatic reactiona For T2 For T3 and T4 Posttraumatic symptoms at T1b For T2 For T3 and T4 Sought help between event and T1 both at the EAP and at the police union Model characteristics Total explained variance (within/between) Additional explained variance

Baseline

Pretraumatic

Peritraumatic

Early posttraumatic

7.34ⴱⴱ 3.65ⴱⴱ N/A N/A

5.84ⴱⴱ 2.11ⴱ 4.05ⴱⴱ 0.40ⴱⴱ

0.31c 0.28c 4.24ⴱⴱ 0.19ⴱ PDEQ (ISR-E/ISR-P)a

⫺0.46c 0.02c 3.76ⴱⴱ 0.17ⴱ PDEQ (ISR-E/ISR-P)a

N/A N/A

N/A N/A

0.32 (0.30/0.53)ⴱⴱ 0.11 (0.10/0.18)

⫺0.03 (–0.03/–0.04)c 0.02 (0.02/0.04)c ASD (BDI)b

N/A N/A N/A

N/A N/A N/A

N/A N/A N/A

1.09 (0.61)ⴱⴱ 0.18 (0.10)c 7.18ⴱⴱ

0.03ⴱⴱ 0.03ⴱⴱ

0.32ⴱⴱ 0.32ⴱⴱ

0.46ⴱⴱ 0.14ⴱⴱ

0.64ⴱⴱ 0.18ⴱⴱ

Note. ASD ⫽ acute stress disorder; BDI-II ⫽ Beck Depression Inventory II; ISR-E ⫽ Initial subjective reaction - Emotional; ISR-P ⫽ Initial subjective reaction - Physical; MPSS ⫽ Modified PTSD Symptom Scale; N/A⫽ not available; PDEQ ⫽ Peritraumatic Dissociative Experiences Questionnaire; Time 1 ⫽ T1; Time 2 ⫽ T2; Time 3 ⫽ T3; Time 4 ⫽ T4. a Coefficients are in units of PDEQ (ISR-E/ISR-P). b Coefficients are in units of ASD symptoms (BDI). c Nonsignificant, p ⬎ 0.05. ⴱ p ⬍ .05. ⴱⴱ p ⬍ .001.

MARCHAND ET AL.

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218

month) and T3 (3 months), which was maintained between T3 and T4 (12 months). All scores for PTSD symptoms were below the clinical range, and the predicted average varied from 7.3 (at T2) to 3.7 (at T3 and T4). At the pretraumatic level, the predictive model (Step 2) highlighted the importance of taking into consideration the use of emotional coping strategies in predicting the intensity of PTSD symptoms, independent of time of assessment. The more police officers resorted to emotional strategies when coping with stress, the more they tended to develop PTSD symptoms. In addition, the more children they have, the more male police officers tend to develop PTSD symptoms. These two variables added 32% of explained variance beyond the effect of time. The level of selfefficacy had a certain predictive value according to the bivariate analyses. However, it did not explain a statistically significant amount of variance beyond what is already explained by the use of emotional coping strategies and the number of children. When peritraumatic variables were added to the predictive models (Step 3), analyses highlighted the added predictive value of the intensity of the reactions during the trauma. The intensity of these reactions was a good predictor of the tendency to subsequently develop PTSD symptoms, but the effect was only statistically significant for the symptoms at T2. In addition, the fact that the inclusion of peritraumatic reactions in the model was associated with a substantial drop in the effect of emotion-oriented coping suggests that the effect of coping on PTSD symptoms is partially mediated by its effect on peritraumatic reactions. Peritraumatic reactions added 14% of explained variance to the model. The duration of the event had a certain predictive value according to the bivariate analyses, but it did not explain a statistically significant amount of unique variance. When early posttraumatic variables were added to the predictive models (Step 4), analyses highlighted the added predictive value of posttraumatic symptoms at T1 and of seeking help at both the EAP and at the police union between the event and T1, which added 18% of explained variance to the model. As with peritraumatic reactions, the effect of early posttraumatic reactions was statistically significant only at T2. As confirmed by post hoc tests (not presented here), the drop in the effect of peritraumatic reactions was associated with the inclusion of early posttraumatic reactions in the model, except for help seeking. This suggests that the effect of peritraumatic reactions on PTSD symptoms is completely mediated by its effect on early posttraumatic symptoms. The negative impact of the media coverage of the event and the level of social support (positive and negative) between the event and T1 also had a certain predictive value according to the bivariate analyses, but these factors did not explain a statistically significant amount of unique variance in the predictive model. In summary, the presented model provides a useful framework that can be adapted to the time of assessment (from a pretraumatic baseline to 5 to 15 days after the event) to predict the emergence of PTSD symptoms for police officers who experienced a traumatic event.

Discussion The present findings support the current state of knowledge regarding the incidence rates and predictive factors of PTSD in police officers. Our results corroborate the findings of a pro-

spective study by Yuan et al. (2011), which also found a low PTSD rate among police officers recruited from New York and California. In this study, only one police officer among 233 officers assessed after 2 years of service reached the cutoff point for a PTSD diagnosis. Other studies have also found a relatively low incidence of current duty-related PTSD, with rates of 7% for police officers in the Netherlands and New Zealand (Carlier et al., 1997; Stephens & Miller, 1998) and 9% in Brazil (Maia et al., 2007). Despite being at high risk of exposure to traumatic events, police workers appear to be quite resilient to stress. This could be explained by various factors. For instance, the selection criteria for hiring new employees may allow for choosing those best able to assume police-related tasks (Marmar, Weiss, Metzler, Ronfeldt, & Foreman, 1996). Police officers are also trained to face stressful situations, which can facilitate resilience (Carlier et al., 1997; Marmar et al., 1996), and allow them to develop extensive experience with a variety of dangerous situations. The low level of symptomatology found in our sample could also be explained by the availability of a free, confidential, and efficient EAP. Another possibility is that police officers may be inclined to underreport symptoms of psychological distress, as the police culture may promote more socially desirable responses in psychological assessments (Perrin et al., 2007; Yuan et al., 2011). Our results are in line with Martin et al. (2009), showing that the intensity of PTSD symptoms is associated with specific risk factors. Risk factors (e.g., emotional coping strategies; number of ASD symptoms; intensity of depressive symptoms; dissociative, emotional, and physical reactions) increase the likelihood of longterm consequences on psychological health after exposure to a traumatic event. It was hypothesized that protective factors would promote adaptation following a traumatic event and prevent the development of PTSD symptoms or reduce their severity. However, unlike Martin et al.’s (2009)study, we failed to identify any protective factor modulating the intensity of symptoms, such as personality hardiness or social support during and after trauma. One possible explanation has to do with the potentially traumatic event that was selected. It is conceivable that the specific event identified according to the DSM–IV–TR’s (American Psychiatric Association, 2000) criteria was not one of the most meaningful in the officer’s career. It can also be that some officers did not experience any particular needs in terms of social support. Nevertheless, our results must be interpreted with caution, as it is possible that the police culture discourages officers to be openly psychologically or physically vulnerable. In addition, two of the three measures of hardiness had an unsatisfactory Cronbach’s alpha that could explain their absence of significant associations with the outcome. Moreover, our study was not entirely prospective because some pretraumatic variables were not measured prior to the traumatic event, but in the days following it. The present study attempted to compensate the limitations identified in previous studies on predictive factors of PTSD in police. For example, these studies are correlational and retrospective, which introduces memory and recall bias and does not allow for drawing causal inferences. The cross-sectional nature of most of them also hinders the identification of specific contributing factors in the development or maintenance of PTSD. In addition, longitudinal studies that identify distinct predictors at varying points in

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PREDICTORS OF PTSD IN POLICE OFFICERS

time, for acute and chronic PTSD, are also lacking. Their inclusion and exclusion criteria are sometimes unclear, and their sample sizes are often small. Therefore, the current research uses a prospective research design and a diversified sample of police officers. It is the first study to explore predictors of PTSD in a sample of Canadian police officers. In addition, the use of standardized instruments allowed the assessment of several predictors that are often overlooked, such as personality hardiness and coping strategies. Moreover, a distinction was made between positive social support and negative social interactions, and various sources of support were evaluated. To our knowledge, it is the first study that monitors posttraumatic symptoms early after a critical incident and at different time intervals in a police sample. The findings of our study have implications for screening, assessment, and primary, secondary, and tertiary prevention (i.e., treatment) of officers exposed to traumatic events in the course of their work. We propose the implementation of prevention and intervention strategies to improve the recovery of police officers exposed to traumatic events. These strategies could be based on the significant predictors identified by our research project and by other empirical studies in the field. Clinically speaking, specific interventions could be developed and adapted in the future, as prominent factors involved in modulating PTSD (e.g., dissociation, emotional and physical reactions, ASD and depressive symptoms) may be modified using psychological strategies. For instance, police organizations could foster resilience in their staff by including in their training programs effective coping strategies such as problem solving, autogenic or applied relaxation, or breathing retraining. Strategies for controlling or better managing intense emotions, reducing physiological activation, or preventing the emergence of dissociative reactions at the time of the trauma could also be taught. In the days following a traumatic event, “psychological first aid” should be provided. Care should be limited to making people feel secure by informing them about the possible psychological consequences and providing them with tangible and emotional support. Preventive interventions could also be developed to implement alternatives to emotion-oriented coping strategies among police officers. Based on our results, seeking help at the police union and at the EAP in the days following a traumatic event could serve as a strong indicator that PTSD symptoms might appear in the following weeks or months. Later, within the first month of the event, various effective postevent strategies should be suggested to officers who have experienced a traumatic event and who have ASD symptoms. One such strategy is to provide brief, intensive, cognitive– behavioral therapy in the form of five weekly sessions starting 2 weeks after the event. Immediate postevent intervention can also promote appropriate social support and encourage the verbalization of emotions in a safe and supportive environment. Tertiary prevention should focus on developing therapeutic treatments based on empirical validated risk and protective factors of PTSD. Finally, the fact that male officers with more than one child might be more at risk of developing PTSD symptoms than other officers is both interesting and intriguing. This result suggests that gender roles moderate the effect of traumatic events on police officers. However, further studies would be required both to replicate and explain this finding.

219 References

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Received October 23, 2013 Revision received September 23, 2014 Accepted December 14, 2014 䡲