Factor Structure Of Posttraumatic Stress Disorder Research Articles

DSM-5-TR prolonged grief disorder and DSM-5 posttraumatic stress disorder are related, yet distinct: confirmatory factor analyses in traumatically bereaved people

ABSTRACT Background: Prolonged grief disorder (PGD) is newly included in the text revision of the DSM-5 (DSM-5-TR). So far, it is unknown if DSM-5-TR PGD is distinguishable from bereavement-related posttraumatic stress disorder (PTSD). Prior research examining the distinctiveness of PTSD and pathological grief focused on non-traumatic loss samples, used outdated conceptualizations of grief disorders, and has provided mixed results. Objective: In a large sample of traumatically bereaved people, we first evaluated the factor structure of PTSD and PGD separately and then evaluated the factor structure when combining PTSD and PGD symptoms to examine the distinctiveness between the two syndromes. Methods: Self-reported data were used from 468 people bereaved due to the MH17 plane disaster (N = 200) or a traffic accident (N = 268). The 10 DSM-5-TR PGD symptoms were assessed with the Traumatic Grief Inventory-Self Report Plus (TGI-SR+). The 20-item Posttraumatic Stress Disorder Checklist for DSM-5 (PCL-5) was used to tap PTSD symptoms. Confirmatory factor analyses were conducted. Results: For PTSD, a seven factor, so-called ‘Hybrid’ model yielded the best fit. For PGD, a univariate factor model fits the data well. A combined model with PGD items loading on one factor and PTSD items on seven factors (associations between PGD and PTSD subscales r ≥ .50 and ≤.71), plus a higher-order factor (i.e. PTSD factors on a higher-order PTSD factor) (association between higher-order PTSD factor and PGD factor r = .82) exhibited a better fit than a model with all PGD and PTSD symptom loading on a single factor or two factors (i.e. one for PGD and one for PTSD). Conclusions: This is the first study examining the factor structure of DSM-5-TR PGD and DSM-5 PTSD in people confronted with a traumatic loss. The findings provide support that PGD constitutes a syndrome distinguishable from, yet related with, PTSD.

Using Exploratory Structural Equation Modeling (ESEM) to Examine the Internal Structure of Posttraumatic Stress Disorder Symptoms.

Several studies have reported the factor structure of posttraumatic stress disorder (PTSD) using confirmatory factor analysis (CFA). The results show models with different number of factors, high correlations between factors, and symptoms that belong to different factors in different models without affecting the fit index. These elements could suppose the existence of considerable item cross-loading, the overlap of different factors or even the presence of a general factor that explains the items common source of variance. The aim is to provide new evidence regarding the factor structure of PTSD using CFA and exploratory structural equation modeling (ESEM). In a sample of 1,372 undergraduate students, we tested six different models using CFA and two models using ESEM and ESEM bifactor analysis. Trauma event and past-month PTSD symptoms were assessed with Life Events Checklist for DSM-5 (LEC-5) and PTSD Checklist for DSM-5 (PCL-5). All six tested CFA models showed good fit indexes (RMSEA = .051-.056, CFI = .969-.977, TLI = .965-.970), with high correlations between factors (M = .77, SD = .09 to M = .80, SD = .09). The ESEM models showed good fit indexes (RMSEA = .027-.036, CFI = .991-.996, TLI = .985-.992). These models confirmed the presence of cross-loadings on several items as well as loads on a general factor that explained 76.3% of the common variance. The results showed that most of the items do not meet the assumption of dimensional exclusivity, showing the need to expand the analysis strategies to study the symptomatic organization of PTSD.

Prevalence and Factor Structure of PTSD in DSM-5 Versus DSM-IV in a National Sample of Sexual Minority Women.

The impact of changes to posttraumatic stress disorder (PTSD) diagnostic criteria from Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV) to Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5) within diverse communities is unclear. Young adult sexual minority women are at high risk for interpersonal violence and other forms of trauma exposure compared with heterosexual populations and sexual minority men. They are also at heightened risk of PTSD. As a result, young adult sexual minority women are a key population of interest when examining the impact of diagnostic criteria changes. The goal of the current study was to evaluate the impact of changes to PTSD diagnostic criteria in sexual minority women. Using an online survey, we administered both the original PTSD Symptom Checklist-S (based on DSM-IV criteria) and a version adapted to assess DSM-5 criteria to a national, nonclinical sample of young adult sexual minority women (N = 767). The DSM-5 symptom criteria fit the data well in confirmatory factor analysis. Current PTSD prevalence was higher under the DSM-5 diagnostic algorithm compared with DSM-IV (18.6% vs. 22.9%; d = 0.15). Compared with DSM-IV, associations between PTSD and depression were stronger using DSM-5 criteria, whereas associations between PTSD and high-risk drinking were reduced. Findings suggest that changes to PTSD diagnostic criteria do not have a major impact on prevalence of PTSD among sexual minority women but may have some impact on observed comorbidities.

Dimensional Structure and Cultural Invariance of DSM V Post-traumatic Stress Disorder Among Iraqi and Syrian Displaced People.

While the factor structure of post-traumatic stress disorder (PTSD) symptoms has been investigated among various traumatized populations in Western and high-income countries, knowledge regarding the validity of factor structure of PTSD among culturally diverse populations in low-and-middle-income countries is limited. The current study examined the factor structure and cultural invariance of PTSD in 521 Iraqi and 993 Syrian war-affected displaced people who were living in the Kurdistan Region of Iraq. Results from confirmatory factor analyses demonstrated that alternative factor models for PTSD, including a new model derived from this population (anhedonia and affect model) resulted in a better fit than the current DSM V models. Taken together, the results showed that a good fit, as well as the measurement invariance of PTSD factors, could be obtained by applying the anhedonia and hybrid model. This study provides further support for the anhedonia and hybrid model of PTSD and fills an important gap in knowledge about the validity of PTSD symptom clusters among Arab and Kurdish populations.

Latent factor structure of PTSD symptoms in veterans with a history of mild traumatic brain injury and close-range blast exposure.

Confirmatory factor analysis (CFA) has previously been employed to examine the latent factor structure of posttraumatic stress disorder (PTSD) symptoms with mixed results. A limited number of studies examined PTSD factor structure among veterans of recent military conflicts. This study examined the relationship between PTSD factor structure and the hallmark conditions of these conflicts, mild traumatic brain injury (mTBI) and close-range blast exposure (CBE). The fit of previously proposed PTSD factor models was compared in a cohort of 387 combat-exposed veterans, with stratified analyses comparing factor structure models between those with a history of military-related mTBI and CBE (n = 106) and those without either of these antecedents (n = 151). CFAs were conducted using criteria from the Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV; American Psychiatric Association, 1994). The 4-factor emotional numbing (EN) model yielded the best fit when using a clinician-administered assessment of PTSD symptoms regardless of mTBI/CBE exposure status. However, when using a self-report measure of PTSD symptom severity, the EN model yielded best fit for those with mTBI/CBE exposure history while the 5-factor dysphoric arousal (DA) model was preferable among combat-exposed veterans with no history of mTBI/CBE exposure. Factors including mTBI and blast exposure and type of assessment tools must be considered when determining preferable PTSD latent factor structure models. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Anger as an underlying dimension of posttraumatic stress disorder

In this study, we examined the underlying role of anger in posttraumatic stress disorder (PTSD). Although anger is currently considered within two symptoms of PTSD (i.e., anger/irritability; and negative emotional state), some research has found that anger is more than just a diagnostic symptom of PTSD. The sample consisted of 375 trauma-exposed individuals that completed the PTSD Checklist-5 and Dimensions of Anger Reactions Scale. Confirmatory factor analysis was used to assess PTSD's factor structure based on the four-factor DSM-5 PTSD model. Subsequently, the model was re-tested, statistically controlling for anger by regressing PTSD's items on an observed anger score. Individual factor loading differences were then compared to determine anger's underlying role. Results indicated that a significant amount of variance in PTSD, at both the item level and factor level, was attributable to an underlying dimension of anger. The largest factor attenuation was for the symptom of irritability/anger and the smallest attenuation was recklessness. The results suggest that anger underlies more of PTSD than the two diagnostic symptom criteria.

PTSD's factor structure and measurement invariance across subgroups with differing count of trauma types

To investigate the effect of the count of traumatizing event (TE) types on post-trauma mental health, several studies have compared posttraumatic stress disorder (PTSD) severity between individuals experiencing one versus multiple TE types. However, the validity of these studies depends on the establishment of measurement invariance of the construct(s) of interest. The current study examined the stability of the most optimal PTSD Model symptom cluster constructs (assessed by the PTSD Checklist for DSM-5 [PCL-5]) across subgroups experiencing one versus multiple TE types. The sample included university students (n = 556) endorsing at least one TE (Stressful Life Events Screening Questionnaire). Using data from the entire sample, results suggest that the PCL-5-assessed Hybrid Model provided a significantly better fit compared to other models. Results also indicated invariance of factor loadings (metric), and intercepts (scalar) for the PCL-5-assessed Hybrid Model factors across subgroups endorsing one (n = 191) versus multiple TE types (n = 365). Our findings thus support the stability, applicability, and meaningful comparison of the PCL-assessed Hybrid Model factor structure (including subscale severity scores) across subgroups experiencing one versus multiple TE types.

The impact of gender on the factor structure of PTSD symptoms among active duty United States military personnel

ObjectivesGender has increasingly been looked at as an important variable in psychological research. Posttraumatic Stress Disorder (PTSD) has long been recognized to have a greater incidence of occurrence in women than men. Factor analytic studies have generally supported the presence of a 4 factor model, although confirmatory factor analysis has acknowledged the influence of factor invariance. Recent studies have found wide variety in the symptom endorsement within samples of individuals diagnosed with PTSD. Invariance of PTSD factor structure across groups holds significant importance in terms of understanding underlying variation in factor structures as a function of type of traumas or gender. This study examined the impact of gender on PTSD factor structure. MethodsSubjects (n=16,146) were active duty military personnel who completed the 2005 Department of Defense (DoD) Survey of Health Related Behaviors Among Active Duty Military Personnel (HRB). The study sample for this analysis included results from men (n=12,119) and women (n=4027) active duty military personnel over the age 18years who completed the HRB survey. Participants averaged M=31.3, SD=8.6years of age. ResultsResults found a four-factor solution fit best for both the group as a whole, and for men and women military personnel. However, the nature of the factors varied when gender was examined. ConclusionThe findings support how PTSD may present differently in men and women, and the need for examination of possible differing experiences of PTSD in populations of trauma survivors. The DSM-5 and potential changes in ICD-11 classifications increase the importance of how gender differences might be evidenced, and in how post trauma schema is manifested when gender is a consideration.

Dimensionality of DSM-5 posttraumatic stress disorder and its association with suicide attempts: results from the National Epidemiologic Survey on Alcohol and Related Conditions-III.

Emerging confirmatory factor analytic (CFA) studies suggest that posttraumatic stress disorder (PTSD) as defined by the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) is best characterized by seven factors, including re-experiencing, avoidance, negative affect, anhedonia, externalizing behaviors, and anxious and dysphoric arousal. The seven factors, however, have been found to be highly correlated, suggesting that one general factor may exist to explain the overall correlations among symptoms. Using data from the National Epidemiologic Survey on Alcohol and Related Conditions-III, a large, national survey of 36,309 U.S. adults ages 18 and older, this study proposed and tested an exploratory bifactor hybrid model for DSM-5 PTSD symptoms. The model posited one general and seven specific latent factors, whose associations with suicide attempts and mediating psychiatric disorders were used to validate the PTSD dimensionality. The exploratory bifactor hybrid model fitted the data extremely well, outperforming the 7-factor CFA hybrid model and other competing CFA models. The general factor was found to be the single dominant latent trait that explained most of the common variance (~76%) and showed significant, positive associations with suicide attempts and mediating psychiatric disorders, offering support to the concurrent validity of the PTSD construct. The identification of the primary latent trait of PTSD confirms PTSD as an independent psychiatric disorder and helps define PTSD severity in clinical practice and for etiologic research. The accurate specification of PTSD factor structure has implications for treatment efforts and the prevention of suicidal behaviors.

PTSD factor structure and relationship with self-construal among internally displaced persons

The present study examined the factor structure of six competing posttraumatic stress disorder (PTSD) models based on the recent changes in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) in a sample that, while highly vulnerable to PTSD, very few studies have focused on—Asians, particularly Filipino internally displaced persons (IDPs). In recognition of the role of culture in PTSD factor structure, we also investigated the associations of the factors of the best-fitting model with self-construal. A sample of 460 IDPs in government resettlement communities participated in the study. Results of confirmatory factor analyses revealed the seven-factor hybrid model composed of intrusion, avoidance, negative affect, anhedonia, externalizing behaviors, anxious arousal, and dysphoric arousal as the best-fitting model. Furthermore, it was found that associations between independent self-construal and PTSD factors were higher than that of interdependent self-construal and PTSD factors.

A Factor Analysis of PTSD with Latino Samples with Substance Use Disorders.

ObjectiveThe Post - Traumatic Stress Disorder (PTSD) factor structure is not a generally agreed upon concept. It has remained controversial and its’ efficacy regarding different trauma presentations is still in question. Therefore, it is imperative that we evaluate different conceptualizations of the PTSD factor structure. This study aims to understand how PTSD is structured when comorbid with Substance Use Disorder (SUD).MethodWe evaluated presentations of PTSD - SUD from a Latino community based sample. This was done using several accepted models of the PTSD factor structure. We then performed an exploratory factor analysis of the factor structure of PTSD when comorbid with SUD.ResultsWe found that the factor structure of PTSD - SUD was different from the structure presented in the DSM - IV and other empirically validated structural models.ConclusionThe factor structure of PTSD may need to include a separate structure when PTSD is comorbid with SUD. Cultural differences when structuring the PTSD diagnosis should also be considered.

An investigation of PTSD's core dimensions and relations with anxiety and depression.

Posttraumatic stress disorder (PTSD) is highly comorbid with anxiety and depressive disorders, which is suggestive of shared variance or common underlying dimensions. The purpose of the present study was to examine the relationship between the latent factors of PTSD with the constructs of anxiety and depression in order to increase understanding of the co-occurrence of these disorders. Data were collected from a nonclinical sample of 186 trauma-exposed participants using the PTSD Checklist and Hospital Anxiety and Depression Scale. Confirmatory factor analyses were conducted to determine model fit comparing 3 PTSD factor structure models, followed by Wald tests comparing the relationships between PTSD factors and the core dimensions of anxiety and depression. In model comparisons, the 5-factor dysphoric arousal model of PTSD provided the best fit for the data, compared to the emotional numbing and dysphoria models of PTSD. Compared to anxious arousal, the dysphoric arousal and numbing factors of PTSD were more related to depression severity. Numbing, anxious arousal, and dysphoric arousal were not differentially related to the latent anxiety factor. The underlying factors of PTSD contain aspects of the core dimensions of both anxiety and depression. The heterogeneity of PTSD's associations with anxiety and depressive constructs requires additional empirical exploration because clarification regarding these relationships will impact diagnostic classification as well as clinical practice.

Factor structure of PTSD, and relation with gender in trauma survivors from India

BackgroundThe factor structure of posttraumatic stress disorder (PTSD) has been extensively studied in Western countries. Some studies have assessed its factor structure in Asia (China, Sri Lanka, and Malaysia), but few have directly assessed the factor structure of PTSD in an Indian adult sample. Furthermore, in a largely patriarchal society in India with strong gender roles, it becomes imperative to assess the association between the factors of PTSD and gender.ObjectiveThe purpose of the present study was to assess the factor structure of PTSD in an Indian sample of trauma survivors based on prevailing models of PTSD defined in the DSM-IV-TR (APA, 2000), and to assess the relation between PTSD factors and gender.MethodThe sample comprised of 313 participants (55.9% female) from Jammu and Kashmir, India, who had experienced a natural disaster (N=200) or displacement due to cross-border firing (N=113).ResultsThree existing PTSD models—two four-factor models (Emotional Numbing and Dysphoria), and a five-factor model (Dysphoric Arousal)—were tested using Confirmatory Factor Analysis with addition of gender as a covariate. The three competing models had similar fit indices although the Dysphoric Arousal model fit significantly better than Emotional Numbing and Dysphoria models. Gender differences were found across the factors of Re-experiencing and Anxious arousal.ConclusionsFindings indicate that the Dysphoric Arousal model of PTSD was the best model; albeit the fit indices of all models were fairly similar. Compared to males, females scored higher on factors of Re-experiencing and Anxious arousal. Gender differences found across two factors of PTSD are discussed in light of the social milieu in India.

DSM-5 posttraumatic stress disorder: Factor structure and rates of diagnosis

Posttraumatic stress disorder (PTSD) is a significant problem among Iraq/Afghanistan-era veterans. To date, however, there has been only limited research on how the recent changes in DSM-5 influence the prevalence and factor structure of PTSD. To address this key issue, the present research used a modified version of a gold-standard clinical interview to assess PTSD among a large sample of Iraq/Afghanistan-era veterans (N = 414). Thirty-seven percent of the sample met DSM-5 criteria for PTSD compared to a rate of 38% when DSM-IV diagnostic criteria were used. Differences in rates of diagnosis between DSM-IV and DSM-5 were primarily attributable to changes to Criterion A and the separation of the “avoidance” and “numbing” symptoms into separate clusters. Confirmatory factor analysis (CFA) was used to compare the fit of the previous 3-factor DSM-IV model of PTSD to the 4-factor model specified in DSM-5, a 4-factor “dysphoria” model, and a 5-factor model. CFA demonstrated that the 5-factor model (re-experiencing, active avoidance, emotional numbing, dysphoric arousal, anxious arousal) provided the best overall fit to the data, although substantial support was also found for the 4-factor DSM-5 model. Low factor loadings were noted for two of the symptoms in the DSM-5 model (psychogenic amnesia and reckless/self-destructive behavior), raising questions regarding the adequacy of fit between these symptoms and the other core features of PTSD. Overall, findings suggest the DSM-5 model of PTSD is an improvement over the previous DSM-IV model of PTSD, but still may not represent the true underlying factor structure of PTSD.

Examining posttraumatic stress disorder's latent structure between treatment-seeking and non-treatment-seeking Filipinos

BackgroundThe discourse of latent structure of posttraumatic stress disorder (PTSD) has been extensive in trauma literature. Although findings have been consistent in rejecting DSM-IV-TR's three-factor model, alternative models are still fervently argued. This study contributes to the discussion by examining and comparing PTSD factor structure of the three most validated models—numbing model (King et al., 1998), dysphoria model (Simms et al., 2002), and dysphoric arousal model (Elhai et al., 2011b)—and determining if these are generalizable across treatment-seeking and non-treatment-seeking Filipinos with exposure to trauma events. MethodsFilipino-Tagalog version of Harvard Trauma Questionnaire (HTQ; Mollica et al., 1992) was administered to a sample of 737 treatment-seeking (n=526) and non-treatment-seeking (n=211) Filipinos who experienced and witnessed varied trauma events. Confirmatory factor analysis (CFA) was conducted involving the three models in order to determine the best-fitting model and generalizability across samples. ResultsResults showed that all three models achieved excellent fit, with dysphoric arousal model slightly fitting better than numbing and dysphoria models in both treatment-seeking and non-treatment-seeking samples. Series of invariance testing, however, indicated that although dysphoric arousal model fits significantly better than dysphoria model, it did not significantly differ from numbing model. Results revealed that aside from the factor loadings, the two groups are noninvariant in all parameters. Treatment-seeking sample had larger intercepts, factor variances and covariances and factor means than non-treatment-seeking group. DiscussionThe findings strongly contribute to the literature by showing how the type of groupings (treatment-seeking vs. non-treatment-seeking) moderates PTSD latent structure. It affirms the suggestion of Biehn et al. (2012) to be cautious in concluding the generalizability of PTSD models in the context that type of participants moderates PTSD's factor structure.

Latent structure of posttraumatic stress disorder symptoms in an adolescent sample one month after an earthquake

Increasing empirical studies suggest that the tripartite posttraumatic stress disorder (PTSD) model described in the DSM-IV does not accurately account for the underlying PTSD factor structure, and several alternative models have been proposed. The present study investigated a newly refined, five-factor model of PTSD symptoms in a sample of Chinese adolescent survivors of an earthquake. A total of 1198 middle school students (653 females, 526 males) with a mean age of 14.4 years (SD = 1.1, range: 11–18) participated in this study one month after an earthquake. The novel five-factor model comprised of intrusion, avoidance, numbing, dysphoric arousal, and anxious arousal demonstrated significantly better fit than two alternative four-factor models. Further analyses revealed differentiable relations between the PTSD factors and external measures of anxiety and depression. These findings provide empirical support for the robustness of five-factor model, and carry implications for further reorganization of PTSD criteria.

An examination of the structure of posttraumatic stress disorder in relation to the anxiety and depressive disorders

The nature and structure of posttraumatic stress disorder (PTSD) has been the subject of much interest in recent times. This research has been represented by two streams, the first representing a substantive body of work which focuses specifically on the factor structure of PTSD and the second exploring PTSD's relationship with other mood and anxiety disorders. The present study attempted to bring these two streams together by examining structural models of PTSD and their relationship with dimensions underlying other mood and anxiety disorders. PTSD, anxiety and mood disorder data from 989 injury survivors interviewed 3-months following their injury were analyzed using a series of confirmatory factor analyses (CFA) to identify the optimal structural model. CFA analyses indicated that the best fitting model included PTSD's re-experiencing (B1-5), active avoidance (C1-2), and hypervigilance and startle (D4-5) loading onto a Fear factor (represented by panic disorder, agoraphobia and social phobia) and the PTSD dysphoria symptoms (numbing symptoms C3-7 and hyperarousal symptoms D1-3) loading onto an Anxious Misery/Distress factor (represented by depression, generalized anxiety disorder and obsessive compulsive disorder). The findings have implications for informing potential revisions to the structure of the diagnosis of PTSD and the diagnostic algorithm to be applied, with the aim of enhancing diagnostic specificity.

Posttraumatic Stress Disorder Symptom Structure in Chinese Adolescents Exposed to a Deadly Earthquake

This present study examined the structure of posttraumatic stress disorder (PTSD) symptoms in a large sample of Chinese adolescents exposed to a deadly earthquake. A total of 2,800 middle school students aged 12 to 18 years participated in the study 6 months after the "Wenchuan Earthquake". Results of confirmatory factor analysis indicated that a five-factor intercorrelated model composed of intrusion, avoidance, numbing, dysphoric arousal, and anxious arousal, fit data significantly better than both the four-factor numbing model King et al. (Psychological Assessment 10:90-96, 1998) and the four-factor dysphoria model Simms et al. (Journal of Abnormal Psychology 111:637-647, 2002). Further examination of the external convergent and discriminant validity revealed that except for the dysphoric arousal factor, the remaining four PTSD factors yielded significantly different correlations with external measures of anxiety vs. depression. The findings add to the limited literature on the factor structure of PTSD in youths and on the five-factor PTSD model. In addition, they provide more detail into the latent psychopathological processes of PTSD, and inform the forthcoming DSM-5.

Posttraumatic stress disorder instrument wording content is associated with differences in factor structure

The authors examined posttraumatic stress disorder (PTSD) item wording differences on the factor structure of PTSD. Nonclinical, trauma-exposed participants were randomly assigned to complete a PTSD measure using item wording content from the PTSD Checklist (n = 182) or PTSD Symptom Scale (n = 203). Compared to the 4-factor emotional numbing PTSD model, the 4-factor dysphoria PTSD model fit best across groups based on smaller Bayesian information criterion (BIC) values. For PTSD Checklist participants, the numbing model's BIC was 6238.54 compared to the dysphoria model's BIC of 6156.03. For the PTSD Symptom Scale, the numbing model's BIC was 6161.38 compared to the dysphoria model's BIC of 6102.87. Groups differed on variable intercepts and residual variances. Instrument and construct implications are discussed.

Comparing posttraumatic stress disorder's symptom structure between deployed and nondeployed veterans.

We tested two empirically validated 4-factor models of posttraumatic stress disorder (PTSD) symptoms using the PTSD Checklist: King, Leskin, King, and Weathers' (1998) model including reexperiencing, avoidance, emotional numbing, and hyperarousal factors, and Simms, Watson, and Doebbeling's (2002) model including reexperiencing, avoidance, dysphoria, and hyperarousal. Our aim was to determine which fit better in two groups of military veterans: peacekeepers previously deployed to a war zone (deployed group) and those trained for peacekeeping operations who were not deployed (nondeployed group). We compared the groups using multigroup confirmatory factor analysis. Adequate model fit was demonstrated among the nondeployed group, with no significant difference between King et al.'s (1998) model (separating avoidance and numbing) and Simms et al.'s (2002) similar model involving a dysphoria factor. A better fitting factor structure consistent with Simms et al.'s (2002) model was found in the deployed group. Comprehensive measurement invariance testing demonstrated significant differences between the deployed and nondeployed groups on all structural parameters, except observed variable intercepts (thus indicating similarities only in PTSD item severity). These findings add to researchers' understanding of PTSD's factor structure, given the revision of PTSD that will appear in the forthcoming 5th edition of the Diagnostic and Statistical Manual of Mental Disorders (American Psychiatric Association, 2010)--namely, that the factor structure may be quite different between groups with and without exposure to major traumatic events.