Relation Between Traumatic Events and Suicide Attempts in Canadian Military Personnel

Transcription

1 Relation Between Traumatic Events and Suicide Attempts in Canadian Military Personnel Shay-Lee Belik, MSc 1 ; Murray B Stein, MD, MPH, FRCPC 2 ; Gordon JG Asmundson, PhD 3 ; Jitender Sareen, MD, FRCPC 4 Objective: To determine whether exposure to particular types of traumatic events was differentially associated with suicide attempts in a representative sample of active military personnel. Method: Data came from the Canadian Community Health Survey: Mental Health and Well-Being Canadian Forces Supplement (CCHS-CFS), a cross-sectional survey that provided a comprehensive examination of mental disorders, health, and the well-being of currently active Canadian military personnel (n = 8441; aged 16 to 54 years; response rate 81.1%). Respondents were asked about exposure to 28 traumatic events that occurred during their lifetime. Suicide attempts were measured using a question about whether the person ever attempted suicide or tried to take [his or her] own life. Results: The prevalence of lifetime suicide attempts for currently active Canadian military men and women was 2.2% and 5.6%, respectively. Sexual and other interpersonal traumas (for example, rape, sexual assault, spousal abuse, child abuse) were significantly associated with suicide attempts in both men (adjusted odds ratios [AORs] ranging from 2.31 to 4.43) and women (AORs ranging from 1.73 to 3.71), even after adjusting for sociodemographics and mental disorders. Additionally, the number of traumatic events experienced was positively associated with increased risk of suicide attempts, indicating a dose response effect of exposure to trauma. Conclusions: The current study is the first to demonstrate that sexual and other interpersonal traumatic events are associated with suicide attempts in a representative sample of active Canadian military men and women. Can J Psychiatry. 2009;54(2): Clinical Implications Clinicians working with military populations should be aware of the presence of a traumatic experience in addition to development of a psychiatric disorder in determining the likelihood of a lifetime suicide attempt. Clinicians working with military populations should specifically inquire about lifetime exposure to sexual and other interpersonal traumatic experiences owing to its association with lifetime suicide attempts. Deployment-related traumatic experiences do not appear to confer additional likelihood of a lifetime suicide attempt above and beyond the presence of development of a psychiatric disorder. Limitations The CCHS-CFS survey did not provide additional information about the exact nature of the traumatic event, including whether the experience was deployment-related. Findings may not be generalizable to other military populations, considering that other military groups may have different levels of exposure to combat and other traumatic events. Owing to the cross-sectional nature of the survey, causal inferences cannot be made. Key Words: suicide, attempts, traumatic events, military, Canadian, trauma, representative The Canadian Journal of Psychiatry, Vol 54, No 2, February

2 There has been increasing concern about the mental health of soldiers during recent years. Importantly, suicide has been noted as the second most common cause of death in the United States military 1 and has increasingly become the focus of research in military groups because of its public health impact. Recent research suggests that veterans are more than twice as likely to die by suicide, compared with the general population. 2 This finding has been corroborated in several military samples 3 5 ; however, other studies have demonstrated conflicting results To date, it is unclear whether military personnel have an increased or decreased risk of suicidal behaviour. Considering evidence that a prior suicide attempt is among the best predictors of subsequent completed suicide 11 and that suicide attempts are prevalent in the community, 12 it is critical to identify risk factors for suicide attempts in a military population. In an investigation of the population-attributable risk of suicidal ideation in a community sample, 38% of the risk for suicidal ideation was attributed to exposure to traumatic events. 13 Similarly, risk for suicidal ideation and suicide attempts is increased among people who have experienced particular traumatic events, independent of the development of a mental disorder. 14 Military personnel, in particular, are exposed to high rates of trauma during participation in combat and peacekeeping operations Numerous studies have shown that combat exposure is highly associated with the development of PTSD, 19,20 but controversy exists around whether combat may also lead to subsequent suicidal ideation, suicide attempts, and completed suicide Evidence from most studies suggests that exposure to an increasing number of traumatic experiences in combat and peacekeeping is associated with increased risk of suicidal behaviour. 15,17,26 29 However, several studies have not found an association between military operations and suicidal behaviour. 18,19 Although combat exposure may be sufficient to explain the development of suicidal behaviour in military personnel, it has been hypothesized that pre-military traumas, particularly childhood traumas, may be a predisposing factor in the development of negative mental health outcomes, such as suicidal Abbreviations used in this article CCHS-CFS CIDI DSM PTSD WMH Canadian Community Health Survey: Mental Health and Well-Being Canadian Forces Supplement Composite International Diagnostic Interview Diagnostic and Statistical Manual of Mental Disorders posttraumatic stress disorder World Mental Health behaviour. 30 As well, there are numerous possible mechanisms to explain this association between traumatic events and suicidal behaviour. First, a direct causal relation may exist between trauma type and suicidal behaviour, whereby trauma exposure leads to subsequent suicidal behaviours. Importantly, childhood trauma has been noted as a determinant of the age of onset of suicidal behaviours. 31 Second, an indirect causal effect may exist, such that trauma exposure leads to mental or physical disorder, which in turn leads to suicidality. Previous research has indicated that suicidal behaviours appear to be partially mediated by mental disorders, including PTSD, among those with traumatic exposure. 14,32 Third, shared risk factors, including environmental, personality, or genetic factors, may predispose people to both exposure to traumatic events and to suicidal behaviours. 33,34 Fergusson et al 34 indicated that poor family functioning, socioeconomic disadvantage, poor parental adjustment, and some personality variables may lead people to be at greater risk of making a suicide attempt. To date, research examining trauma in military samples, other than combat-related trauma, has been scarce and limited in numerous ways. First, most studies have used treatment-seeking samples of military personnel, representing a potential selection bias. Second, most studies have not included a thorough assessment of lifetime experiences with a wide range of traumatic events. The current study addressed these limitations by using the CCHS-CFS, a landmark survey that provided the first comprehensive examination of mental disorders, health, and well-being of Canadian military personnel. The CCHS-CFS is the first military mental health survey in the world to use a multistage sampling design to acquire a sample that is representative of all active Canadian military personnel. Further strengths of the CCHS-CFS are the use of a large sample size (more than 8000 active military personnel), a state-of-the-art diagnostic interview (CIDI) 35 to examine the prevalence of several common mental disorders, and the inclusion of a wide range of traumatic events. Importantly, this dataset allows for consideration of the impact of each of the traumatic events independently. The specific aims of this study were: to examine the prevalence of traumatic events and suicide attempts in a large representative military sample; to examine whether exposure to different types of traumatic events was differentially associated with suicide attempts; and, to examine whether exposure to multiple types of traumatic events exhibits a dose response effect with suicide attempts. We hypothesize that the relation between the traumatic event and suicide attempts will be partially mediated by presence of a mental disorder diagnosis. As such, Figure 1 illustrates the theoretical model that was used to guide these analyses. 94 La Revue canadienne de psychiatrie, vol 54, no 2, février 2009

3 Relation Between Traumatic Events and Suicide Attempts in Canadian Military Personnel Figure 1 Hypothesized mediation model used to guide the analyses Trauma exposure Trauma exposure Suicidal behavior Suicidal behaviour Psychiatric disorder Psychiatric disorder Method Survey The current analysis was conducted using the CCHS-CFS. Data for the CCHS-CFS were collected in a joint collaboration by Statistics Canada and the Department of National Defence. 36 The survey employed a multistage sampling framework to ensure the representativeness of the sample in relation to the Canadian military. The first stage of sampling was to divide the Canadian Forces by regular or reserve membership. Reserve members were included in the target population if they had been active in the Canadian Forces within the previous 6 months. The second stage of sampling was stratification by rank and sex. For this purpose, military rank was grouped into 3 categories: junior grouping (included private, corporal, and master corporal), senior grouping (included sergeant, warrant officer, master warrant officer, and chief warrant officer), and officer grouping (included officer cadet, second lieutenant, lieutenant, captain, and major). Men were divided into these 3 levels of rank and women were divided into 2 levels of rank (senior and officer groupings were combined) because of smaller cell sizes for women. Within each of these strata, the sample was further divided by region (Atlantic, Quebec, Ontario, and Prairies) and Canadian Forces environment (air, land, sea, and communications). This approach was used to ensure proportional representation of units for each region and Canadian Forces element. Data were collected using face-to-face interviews by trained Statistics Canada interviewers in private on-base rooms between May and December The sample consisted of 5155 regular force members (response rate 79.5%) and 3286 reserve force members (response rate 83.5%) between the ages of 16 and 54 years. 36 For the sake of anonymity, no information was available as to the specific deployment location of the soldiers. However, based on the age of the sample and the timing of the interviews, it is likely that people included were involved in several different missions, including those to Iraq (that is, the first Gulf War), Rwanda, Somalia, and the former Yugoslavia. Measures Traumatic Events. All respondents were asked about exposure to a comprehensive list of 28 traumatic events that occurred during their lifetime. This 28-item trauma exposure measure was abstracted from the PTSD section of the WMH version of the CIDI. Respondents were able to endorse multiple traumatic events, allowing examination of the impact of each of the 28 traumatic events independently. For the purposes of this study, and for ease of discussion, we combined the traumatic events into conceptually related categories (that is, sexual trauma, other interpersonal, accident and [or] other unexpected, and deployment-related) based on the traumatic events questions themselves. Mental Disorders. The content of the survey was partly based on a selection of mental disorders from the WMH Survey initiative. 35 The World Health Organization CIDI Version 2.1 was used to generate diagnoses according to the definitions and criteria of both the International Classification of Diseases and the DSM-IV. 37 The CIDI is a fully structured instrument for use by lay interviewers without clinical experience and has been shown to have high levels of reliability and consistency with clinician-based diagnoses of the DSM disorders assessed in this survey. The interviewers were The Canadian Journal of Psychiatry, Vol 54, No 2, February

4 trained according to WMH standards. 35 The methodology of the CCHS has been published elsewhere. 38 Lifetime prevalence of the following DSM-IV mental disorders was assessed: major depressive disorder, panic disorder, social phobia, generalized anxiety disorder, and PTSD. The diagnosis of PTSD was based on exposure to the list of 28 possible traumatic events. If respondents endorsed multiple traumatic events, they were asked to identify the event that was most upsetting to them. The CIDI Short Form was used to assess alcohol use disorders based on the criteria of the DSM-IV, where 3 symptoms or more indicated alcohol dependence. 39 As alcohol abuse was not measured in the survey, we created a Heavy Alcohol Use variable based on previous literature. 40 Past-year Heavy Alcohol Use was identified using the following question: How often in the past 12 months have you had 5 or more drinks on one occasion? Respondents were able to choose from 1. never, 2. less than once a month, 3. 2 to 3 times a month, 4. once a week, or 5. more than once a week. Respondents endorsing never or less than once a month were classified as not having Heavy Alcohol Use, whereas the remaining respondents were classified as having Heavy Alcohol Use. Suicidal Behaviours. Lifetime suicidal ideation was assessed with the following question: Did you seriously think about committing suicide or taking your own life? Lifetime suicide attempts were assessed using a question about whether the person ever attempted suicide or tried to take [his or her] own life. Analyses The appropriate estimation procedures according to Statistics Canada regulations were followed for all data analyses using this dataset. We employed the appropriate statistical bootstrapping weights provided by Statistics Canada to ensure the representativeness of the data to the Canadian Forces target population. All the percentages and regression analyses are based on the weighted sample, which takes into account nonresponse and provides estimates that are generalizable to the Canadian Forces population. The Balanced Repeated Replication technique in the SUDAAN program 41 was used to perform the bootstrapping procedure of design-based variance estimation to calculate standard errors required for data with a complex sampling design. All analyses were stratified by sex, as previous literature suggests that males and females differ in risk for suicidal behaviour 12 and exposure to traumatic events. 42,43 In addition, most of the work in this area has looked exclusively at male populations. Therefore stratification by sex allows ease of comparison of the results to previous findings. The dependent variable for all analyses was a dichotomous suicide attempt variable, which compared people with a lifetime suicide attempt to people who had neither a suicide attempt nor suicidal ideation in their lifetime. Suicidal ideation represents a level of severity of distress, ranging from a passive death wish to an active intent to end one s own life. To rule out people with serious suicidal ideation, conceptualized as part of a progression toward more severe forms of suicidality, 44 the variable was created so as to ensure a healthy comparison group for all analyses. This method has been used in previous studies. 45 First, we investigated the prevalence of each traumatic event type and suicide attempts both in men and in women. Second, we used multiple logistic regression models to explore the relation between each of the traumatic events and suicide attempts. Three models were investigated: unadjusted; adjusted for sociodemographic factors, including age, marital status, income, education, rank (junior, senior, or officer), and type of service force (regular, compared with reserve); and, adjusted for sociodemographic factors, the presence of any lifetime mental disorder diagnosis, and a comorbidity variable (3 or more mental disorders) used as a proxy for mental disorder severity. To account for multiple comparisons and the exploratory nature of the analyses, we have presented a more conservative P value, P < 0.01 and 95% confidence intervals, for all regression analyses. Results Table 1 demonstrates the lifetime prevalence of each of the traumatic events both in men and in women. Most traumatic events were experienced at a higher rate in males; however, females were more likely to report exposure to spousal abuse, rape, sexual assault, and stalking. The majority of both sexes endorsed lifetime exposure to at least one of the traumatic events (86.7% in men, 80.5% in women). In fact, a large proportion of people experienced high rates of traumatic exposure, with many reporting the experience of 3 or more traumatic events (57.8% in men, 45.2% in women). The number of traumatic events experienced in the sample ranged from 0 to 27 events, with a mean of 3.47 events (SD 3.10). Table 2 shows the prevalence of lifetime suicide attempts, demonstrating that women were significantly more likely than men to report a suicide attempt at some point in their lifetime (5.6%, compared with 2.2%, respectively). Table 3 shows the relation between lifetime traumatic exposure and lifetime suicide attempts in men. Importantly, exposure to combat or peacekeeping operations was not significantly associated with an increased risk of suicide 96 La Revue canadienne de psychiatrie, vol 54, no 2, février 2009

5 Relation Between Traumatic Events and Suicide Attempts in Canadian Military Personnel attempts. Of the other deployment-related events, the relations between witnessing atrocities was significant only prior to adjustment for mental disorders and comorbidity, whereas having purposely injured, tortured, or killed someone with suicide attempts remained significant following adjustment (AOR = 2.69, 95% CI 1.09 to 6.61). Sexual traumas and other interpersonal traumas were all significantly associated with increased likelihood of suicide attempts (AORs ranging from 2.31 for having been badly beaten up to 4.43 for being abused as a child), even after adjustment for sociodemographics, mental disorders, and comorbidity. Table 4 displays the relation between lifetime traumatic exposure and lifetime suicide attempts in women. In these models, none of the deployment-related exposures were significantly associated with suicide attempts. Similar to men was the positive significant association between sexual traumas and other interpersonal traumas and suicide attempts. Women were nearly 2 to 4 times more likely to endorse a suicide attempt when they had experienced a sexual or interpersonal trauma, with most of the relations remaining significant after adjusted for sociodemographics, mental disorders, and comorbidity (AORs ranging from 1.73 for witnessing domestic violence to 3.71 for having been abused by a spouse). The exception was being mugged, which dropped to nonsignificance in the final model. Additional analyses were performed to determine whether increasing numbers of traumatic events was increasingly associated with suicide attempts. These analyses revealed a significant positive association between increasing numbers of traumatic exposures and higher likelihood of suicide attempts both in men (AOR = 1.17, 95% CI 1.09 to 1.24) and in women (AOR = 1.18, 95% CI 1.09 to 1.27), even after adjustment for sociodemographics, lifetime mental disorder diagnoses, and mental disorder comorbidity. This relation was nearly identical in both sexes. Discussion To our knowledge, this study is the first to examine a wide range of traumatic events, including childhood traumas, in relation to suicide attempts in a representative military sample. The current study adds to the growing literature regarding the contribution of deployment-related and other traumatic exposures to suicidal behaviours in this population. The specific findings of this study illustrate that exposure to certain types of traumatic events appears to be differentially associated with suicide attempts. Of particular importance, sexual traumas and other interpersonal traumatic events emerge as the events with the highest likelihood of associated suicide attempts. In most cases, this relation held even after accounting for the effect of a diagnosable mental disorder. In an investigation of the relation between traumatic events and suicidality in a primary care sample, 46 a history of attempted suicide was directly linked with a history of sexual abuse. The authors hypothesized that sexual abuse differs from other trauma types owing to perpetrator contact with the victim s body, the intrusive physical quality of the abuse, and the use of force, which could be related to the person s perceptions of increased severity. 47 These findings are consistent with previous research in civilian populations denoting an association between traumatic events and suicidal behaviours, with and without a diagnosis of PTSD. 14,48 When comparing models before and after adjustment for mental disorders both in men and in women, it becomes clear that mental disorders accounted for a significant portion of the association between suicide attempts and traumatic experiences, as evidenced by a reduction in odds ratios. These findings illustrate the importance of knowing about both the diagnosis of a mental disorder and traumatic exposure, especially when the person has experienced a sexual and (or) other interpersonal trauma, when examining presence of a lifetime suicide attempt. The results lend support to our hypothesis of a mediation model, illustrating that the relation between traumatic events and suicidal behaviour is partially mediated by mental disorders. One study in a sample of US active duty male soldiers has identified adverse childhood experiences as a significant predictor of mental health symptoms, above and beyond the expected contribution of combat trauma. 49 In line with previous findings that pre-military traumas, particularly childhood traumas, may be predisposing factors in developing negative mental health outcomes in soldiers, 30,49 51 the current results emphasize the significance of these types of events in terms of suicidal behaviours in military personnel. Our study also replicates parallel findings from studies in general population samples, 14,52 again highlighting the importance of childhood and interpersonal traumas on suicidal behaviour. In contrast, the data suggest that exposure to deployment-related events, such as combat or witnessing atrocities, are insufficient to explain the development of suicidal behaviour in military personnel above and beyond the diagnosis of a mental disorder. These findings are echoed by similar studies that have identified lower suicide risk in military men, than in nonmilitary men Further, our results indicate that likelihood of a lifetime suicide attempt increases with an increasing number of traumatic events. This is consistent with prior work that has revealed evidence for a dose response relation in terms of the contribution of multiple traumatic events on mental health outcomes, including suicidal behaviour, both in the general population 14,53,54 and in military samples. 49 The Canadian Journal of Psychiatry, Vol 54, No 2, February

6 Table 1 Prevalence of traumatic events in the sample Prevalence of traumatic events Lifetime exposure to traumatic events n Men, % (95% CI) Women, % (95% CI) Deployment-related Have you ever participated in combat, either as a member of a military, or as a member of an organized non-military group? [Combat] Have you ever served as a peacekeeper or relief worker in a war zone or in a place where there was ongoing terror of people because of political, ethnic, religious, or other conflicts? [Peacekeeper] Have you ever seen atrocities or massacres such as mutilated bodies or mass killings? [Witness atrocities] Have you ever purposely injured, tortured, or killed another person? [Purposely injured or killed] Accident or other unexpected Were you ever involved in a life-threatening motor vehicle accident? [Motor vehicle accident] (16.5 to 18.7) (37.9 to 40.7) (13.4 to 15.4) (3.8 to 5.1) (25.5 to 28.1) Were you ever in any other life-threatening accident, including on your job? [Other accident] (16.9 to 19.1) Were you ever exposed to a toxic chemical or substance that could cause you serious harm? [Toxic chemical exposure] Were you ever in a man-made disaster, like a fire started by a cigarette, or a bomb explosion? [Man-made disaster] Were you ever involved in a major natural disaster, like a devastating flood, hurricane, or earthquake? [Natural disaster] Has someone very close to you ever died unexpectedly; for example, they were killed in an accident, murdered, committed suicide, or had a fatal heart attack at a young age? [Unexpected death] Other than what you already reported, have you ever had a son or daughter who had a life-threatening illness or injury? [Child illness or injury] (22.2 to 24.7) (18.1 to 20.4) (12.3 to 14.3) (36.8 to 39.5) (4.9 to 6.2) Have you ever had a life-threatening illness? [Life-threatening illness] (6.8 to 8.3) Have you ever seen someone being badly injured or killed, or unexpectedly seen a dead body? [Witnessed death] Have you ever done something that accidentally led to the serious injury or death of another person? [Caused death accidentally] Sexual trauma The next 2 questions are about sexual assault. We define sexual assault as anyone forcing you or attempting to force you into any unwanted sexual activity, by threatening you, holding you down, or hurting you in some way. Has this ever happened to you? [Raped] Has anyone ever touched you against your will in any sexual way? By this I mean unwanted touching or grabbing, to kissing or fondling? [Sexual assault] Other interpersonal As a child, were you ever badly beaten by your parents or the people who raised you? [Child abuse] (45.1 to 48.0) (2.8 to 3.9) (2.0 to 2.5) (5.8 to 7.3) (5.6 to 7.0) Were you ever badly beaten by a spouse or romantic partner? [Spousal abuse] (0.9 to 1.5) Were you ever badly beaten up by anyone else? [Other person abused you] (12.2 to 14.2) When you were a child, did you ever witness serious physical fights at home, like your father beating up your mother? [Witnessed domestic violence] Has someone ever stalked you that is, followed you or kept track of your activities in a way that made you feel you were in serious danger? [Stalked] (10.9 to 12.8) (3.3 to 4.4) Were you ever mugged, held up, or threatened with a weapon? [Mugged] (20.8 to 23.1) Were you ever kidnapped or held captive? [Kidnapped] (2.1 to 3.0) 6.6 (5.6 to 7.9) 16.3 (14.7 to 17.9) 3.6 (2.9 to 4.5) 14.6 (13.2 to 16.2) 6.1 (5.1 to 7.2) 9.3 (8.1 to 10.7) 12.2 (10.9 to 13.6) 5.1 (4.2 to 6.2) 36.3 (34.3 to 38.4) 3.7 (3.0 to 4.5) 6.5 (5.6 to 7.6) 23.0 (21.3 to 24.8) 21.0 (19.4 to 22.8) 36.7 (34.7 to 38.8) 6.3 (5.3 to 7.4) 7.1 (6.1 to 8.3) 3.1 (2.5 to 4.0) 14.6 (13.1 to 16.1) 15.1 (13.6 to 16.6) 7.7 (6.6 to 8.9) 1.4 (1.0 to 2.0) 98 La Revue canadienne de psychiatrie, vol 54, no 2, février 2009

7 Relation Between Traumatic Events and Suicide Attempts in Canadian Military Personnel Table 1 continued Prevalence of traumatic events Lifetime exposure to traumatic events n Men, % (95% CI) Women, % (95% CI) Civilian in war or refugee Were you ever an unarmed civilian in a place where there was a war, revolution, military coup, or invasion? [Civilian in war zone] Have you ever lived as a civilian in a place where there was ongoing terror of civilians for political, ethnic, religious, or other reasons? [Civilian in religious terror] Were you ever a refugee that is, did you ever flee from your own home to a foreign country or place to escape danger or persecution? [Refugee] Has anyone very close to you ever had an extremely traumatic experience, like being kidnapped, tortured, or sexually assaulted? [Event happened to other] Other than what you reported, have you ever experienced any other life threatening event? [Other event] (4.4 to 5.7) (4.3 to 5.5) 2.9 (2.2 to 3.7) 2.9 (2.2 to 3.6) (14.8 to 17.0) (7.7 to 9.3) Exposure to any of the above traumatic events (85.7 to 87.6) Number of traumatic events None (12.4 to 14.3) (14.2 to 16.2) (12.9 to 14.8) 3 or more (56.3 to 59.2) Note: Unweighted ns; weighted percentages = cell size too small to be reported (n <6) 17.1 (15.5 to 18.8) 3.4 (2.7 to 4.2) 80.5 (78.7 to 82.1) 19.5 (17.9 to 21.3) 19.0 (17.3 to 20.7) 16.4 (14.9 to 18.0) 45.2 (43.0 to 47.3) Table 2 Prevalence of lifetime suicide attempts in males and females Men n % (95% CI) Women n % (95% CI) No (97.3 to 98.2) (93.2 to 95.4) Note: Unweighted ns; weighted percentages Suicide attempts Yes (1.8 to 2.7) (4.6 to 6.7) The findings of the current study should be interpreted with due consideration of the following limitations. First, the CCHS-CFS by design is able to capture suicide attempts, but not completed suicide. Therefore, the risk factors identified here may be specific to those who attempt suicide and may not be generalizable to soldiers who complete suicide. Second, the present findings may not be generalizable to other military populations, considering that other military groups may have different levels of exposure to combat and other traumatic events. Third, owing to the cross-sectional nature of the survey, causal inferences cannot be made. Information was not available in the survey for the age at which each traumatic event was experienced or suicide attempts occurred, such that temporal examination of the sequencing of exposure to trauma with onset of suicidal behaviour (and mental disorders) was not possible. However, some of the traumatic events assessed did include specific phrases indicating that the event had to have happened in childhood. As such, some temporality can be assumed for the association between particular childhood traumatic events and suicide attempts. For The Canadian Journal of Psychiatry, Vol 54, No 2, February

8 Table 3 Association between lifetime traumatic events and suicide attempts in males Traumatic event OR (95% CI) AOR1 (95% CI) AOR2 (95% CI) Deployment-related Combat 1.39 (0.82 to 2.38) 1.25 (0.70 to 2.21) 1.15 (0.62 to 2.12) Peacekeeping 0.96 (0.61 to 1.53) 0.84 (0.51 to 1.38) 0.82 (0.47 to 1.43) Witness atrocities 1.96 (1.19 to 3.22) a 1.97 (1.17 to 3.31) a 1.68 (0.94 to 3.01) Purposely injured or killed 4.37 (2.09 to 9.13) a 3.59 (1.60 to 8.06) a 2.69 (1.09 to 6.61) b Accident or other unexpected Auto accident 1.09 (0.65 to 1.83) 1.07 (0.64 to 1.80) 0.91 (0.50 to 1.68) Other accident 1.85 (1.12 to 3.04) b 1.78 (1.06 to 2.99) b 1.59 (0.90 to 2.81) Toxic chemical exposure 2.02 (1.27 to 3.24) a 1.87 (1.14 to 3.06) b 1.86 (1.09 to 3.18) b Man-made disaster 1.54 (0.87 to 2.72) 1.41 (0.79 to 2.53) 1.35 (0.73 to 2.50) Natural disaster 1.41 (0.83 to 2.41) 1.29 (0.73 to 2.26) 1.23 (0.65 to 2.31) Unexpected death 1.43 (0.94 to 2.16) 1.41 (0.93 to 2.16) 1.17 (0.71 to 1.95) Child illness or injury 1.15 (0.42 to 3.10) 1.15 (0.42 to 3.18) 0.64 (0.18 to 2.22) Life threatening illness 2.34 (1.16 to 4.69) b 2.20 (1.05 to 4.63) b 2.25 (1.04 to 4.89) b Witness death 1.38 (0.90 to 2.13) 1.34 (0.87 to 2.08) 1.25 (0.75 to 2.08) Caused death accidentally 3.33 (1.40 to 7.95) a 2.92 (1.10 to 7.72) b 2.16 (0.73 to 6.37) Sexual trauma Raped (4.62 to 22.41) a 8.56 (3.66 to 19.99) a 4.29 (1.47 to 12.53) a Sexual assault 6.38 (3.74 to 10.87) a 6.57 (3.77 to 11.45) a 3.73 (1.89 to 7.34) a Other interpersonal Child abuse 7.44 (4.56 to 12.43) a 6.51 (3.70 to 11.49) a 4.43 (2.35 to 8.36) a Spouse abused you Other person abused you 3.66 (2.37 to 5.67) a 3.24 (2.04 to 5.15) a 2.31 (1.34 to 3.96) a Witness to domestic violence 4.32 (2.65 to 7.05) a 4.01 (2.40 to 6.72) a 3.43 (1.94 to 6.04) a Stalked 5.15 (2.58 to 10.29) a 4.83 (2.36 to 9.89) a 3.71 (1.56 to 8.83) a Mugged 2.66 (1.73 to 4.09) a 2.39 (1.53 to 3.72) a 2.45 (1.53 to 3.91) a Kidnapped 4.33 (1.77 to 10.60) a 3.80 (1.49 to 9.69) a 3.44 (1.23 to 9.62) b Civilian in war zone or refugee Civilian in war zone 1.51 (0.61 to 3.75) 1.48 (0.58 to 3.79) 1.54 (0.56 to 4.19) Civilian in religious terror 2.22 (1.06 to 4.66) b 2.46 (1.12 to 5.38) b 2.38 (1.00 to 5.72) b Refugee Event happened to other 3.39 (2.12 to 5.40) a 3.08 (1.87 to 5.07) a 2.07 (1.17 to 3.64) a Other trauma 3.01 (1.71 to 5.33) a 3.26 (1.81 to 5.87) a 2.57 (1.38 to 4.77) a = cell size too small to be reported (n <6). AOR1 = adjusted for sociodemographic factors, which includes age, marital status, income, education, rank (junior, senior, officer), and type of service (regular, compared with reserve). AOR2 = adjusted for sociodemographic factors, presence of any lifetime mental disorder, and comorbidity (3 or more mental disorders). a P<0.05; b P< La Revue canadienne de psychiatrie, vol 54, no 2, février 2009

9 Relation Between Traumatic Events and Suicide Attempts in Canadian Military Personnel Table 4 Association between lifetime traumatic events and suicide attempts in females Traumatic event OR (95% CI) AOR1 (95% CI) AOR2 (95% CI) Deployment-related Combat 1.72 (0.88 to 3.36) 1.46 (0.73 to 2.94) 1.30 (0.63 to 2.68) Peacekeeping 1.55 (0.94 to 2.56) 1.26 (0.73 to 2.18) 1.15 (0.62 to 2.16) Witness atrocities 1.45 (0.59 to 3.52) 1.43 (0.57 to 3.58) 0.96 (0.37 to 2.50) Purposely injured or killed Accident or other unexpected Auto accident 1.48 (0.88 to 2.51) 1.50 (0.88 to 2.57) 1.28 (0.66 to 2.48) Other accident 2.35 (1.24 to 4.47) a 2.43 (1.26 to 4.70) a 1.91 (0.97 to 3.77) Toxic chemical exposure 1.50 (0.79 to 2.84) 1.21 (0.62 to 2.36) 1.25 (0.62 to 2.50) Man-made disaster 2.92 (1.55 to 5.52) a 2.67 (1.40 to 5.10) a 2.16 (1.02 to 4.55) b Natural disaster 1.52 (0.87 to 2.66) 1.42 (0.81 to 2.49) 1.11 (0.55 to 2.26) Unexpected death 1.53 (1.05 to 2.24) b 1.47 (1.00 to 2.16) b 1.03 (0.65 to 1.63) Child illness or injury 1.33 (0.47 to 3.79) 1.42 (0.48 to 4.18) 1.07 (0.31 to 3.65) Life threatening illness 1.52 (0.74 to 3.12) 1.55 (0.75 to 3.23) 0.82 (0.30 to 2.28) Witness death 1.51 (1.01 to 2.26) b 1.50 (0.98 to 2.29) 1.16 (0.69 to 1.95) Caused death accidentally Sexual trauma Raped 5.63 (3.76 to 8.42) a 4.66 (3.05 to 7.13) a 2.54 (1.55 to 4.18) a Sexual assault 6.21 (4.09 to 9.41) a 5.63 (3.68 to 8.62) a 3.41 (2.09 to 5.57) a Other interpersonal Child abuse 5.13 (3.11 to 8.44) 3.98 (2.29 to 6.93) a 2.34 (1.15 to 4.75) b Spouse abused you 5.64 (3.53 to 8.99) a 4.79 (2.91 to 7.89) a 3.71 (1.97 to 6.99) a Other person abused you 6.34 (3.15 to 12.74) a 4.93 (2.26 to 10.73) a 3.08 (1.04 to 9.14) b Witness to domestic violence 2.48 (1.63 to 3.78) a 2.38 (1.54 to 3.70) a 1.73 (1.00 to 3.01) b Stalked 2.75 (1.77 to 4.26) a 2.58 (1.61 to 4.12) a 1.86 (1.09 to 3.19) b Mugged 2.17 (1.28 to 3.67) a 2.40 (1.38 to 4.17) a 1.71 (0.89 to 3.29) Kidnapped 4.27 (1.38 to 13.18) a 3.29 (0.88 to 12.34) 1.49 (0.36 to 6.11) Civilian in war zone or refugee Civilian in war zone 1.33 (0.40 to 4.45) 1.31 (0.39 to 4.38) 0.98 (0.27 to 3.56) Civilian in religious terror 0.24 (0.08 to 0.76) b 0.27 (0.08 to 0.90) b 0.22 (0.07 to 0.71) a Refugee Event happened to other 2.69 (1.77 to 4.07) 2.47 (1.60 to 3.82) a 2.21 (1.34 to 3.62) a Other trauma 2.15 (0.84 to 5.48) 2.24 (0.86 to 5.86) 1.10 (0.36 to 3.37) = cell size too small to be reported (n <6) AOR1 = adjusted for sociodemographic factors, which includes age, marital status, income, education, rank (junior, senior, officer), and type of service (regular, compared with reserve) AOR2 = adjusted for sociodemographic factors, presence of any lifetime mental disorder, and comorbidity (3 or more mental disorders) a P<0.05; b P<0.01 The Canadian Journal of Psychiatry, Vol 54, No 2, February

10 other traumatic events, it is possible that the event occurred following the suicide attempt. For example, it would be impossible for a combat-related traumatic experience in adulthood to affect a suicide attempt that took place in adolescence. Therefore, this bias may selectively affect the associations demonstrated. Fourth, the survey did not provide additional information around the exact nature of the traumatic event, including whether or not the event occurred during a deployment or took place prior to or subsequent to military involvement. Hence, traumatic events categorized as deploymentrelated may have occurred outside of the context of a military deployment and those categorized in other groupings may have happened during a deployment. Nevertheless, the events we have categorized as deployment-related events would be unlikely to occur in the day-to-day lives of most Canadian civilians, suggesting that this categorization is likely to be accurate. Future studies would benefit from the inclusion of details around the timing and location of the traumatic event(s). Fifth, although mental disorder diagnoses according to trained lay interviewer-based assessment using the CIDI have been demonstrated to be reliable, they may not match the accuracy of clinician-based assessment. Sixth, previous work has noted difficulties in measuring suicide attempts, in that respondents may have understood the question quite differently depending on the time of the survey, their emotional state, or their interpretation of the question itself Finally, it should be noted that the CCHS-CFS sample is likely to underestimate the magnitude of true associations between traumatic events and suicide attempts. People with the greatest severity of emotional problems following deployment were likely no longer active in the military at the time of the survey, and therefore were not included in the current sample. Conclusions In summary, the current study indicates that sexual and other interpersonal traumas are highly associated with suicide attempts both in men and in women currently active in the Canadian military. Additionally, increasing levels of traumatic exposure are associated with a further increased likelihood of suicide attempts in this population. Most previous work in this area has focused on completed suicides, not suicide attempts; yet, suicide attempts have been shown to be highly associated with future completions. 11 Therefore, these findings provide important information that may aid in evaluations of suicidal behaviour and the role of traumatic experiences in military personnel. Clinicians working with military populations should inquire about exposure to sexual and other interpersonal traumatic experiences, as well as mental disorder diagnoses, when suicidal behaviour is present. Acknowledgements Preparation of this article was supported by: a Manitoba Health Research Council Graduate Studentship awarded to Ms Belik; a Western Regional Training Centre studentship funded by Canadian Health Services Research Foundation, Alberta Heritage Foundation for Medical Research, and Canadian Institutes of Health Research awarded to Ms Belik; New Emerging Team Grant PTS from the Canadian Institutes of Health Research (CIHR) Institute of Neurosciences, Mental Health and Addiction; a CIHR operating grant; CIHR New Investigator grant awarded to Dr Sareen; and, a Career Development (K24) Award from the National Institutes of Health (MH64122) to Dr Stein. The opinions expressed in this paper do not represent the opinions of Statistics Canada. The authors thank Brian J Cox for his thoughtful feedback on this manuscript. References 1. Ritchie EC, Keppler WC, Rothberg JM. Suicidal admissions in the United States military. 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Suicide Life Threat Behav. 1996;26(3): Manuscript received January 2008, revised, and accepted May This paper was presented at the Canadian Psychiatric Association Annual Meeting in Montreal, Quebec, November 14 18, Student, Department of Community Health Sciences, University of Manitoba, Winnipeg, Manitoba; Research Assistant, Department of Psychiatry, University of Manitoba, Winnipeg, Manitoba. 2 Professor, Departments of Psychiatry and Family and Preventive Medicine, University of California San Diego, La Jolla, California. 3 Professor, Department of Psychology, Anxiety and Illness Behaviours Laboratory, University of Regina, Regina, Saskatchewan; CIHR Investigator, University of Regina, Regina, Saskatchewan. 4 Associate Professor, Departments of Psychiatry, Community Health Sciences, and Psychology, University of Manitoba, Winnipeg, Manitoba; CIHR New Investigator, University of Manitoba, Winnipeg, Manitoba. Address for correspondence: Ms S Belik, PZ Bannatyne Avenue, Winnipeg, MB R3E 3N4; sbelik@hsc.mb.ca The Canadian Journal of Psychiatry, Vol 54, No 2, February