Posttraumatic Diagnostic Scale

1. Abstract

The Posttraumatic Diagnostic Scale (PDS) is a widely utilized, psychometrically validated self-report instrument developed by Edna B. Foa and colleagues (1997) to assess, screen for, and quantify the severity of Posttraumatic Stress Disorder (PTSD) according to the diagnostic criteria delineated in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). Comprising four dedicated sections across 49 total operational inquiries, the instrument guides respondents through trauma identification (Part 1), index trauma specification and Criterion A validation (Part 2), a 17-item core symptom assessment corresponding directly to DSM-IV criteria B, C, and D (Part 3), and an evaluation of functional impairment across nine life domains corresponding to Criterion F (Part 4). Part 3 provides a continuous Symptom Severity Score ranging from 0 to 51, categorized into clinical severity strata: mild (≤10), moderate (11–20), moderate-to-severe (21–35), and severe (≥36), alongside a categorical diagnostic algorithm requiring full satisfaction of DSM-IV Criteria A through F.

Extensive psychometric investigations have established that the PDS exhibits exemplary internal consistency (Cronbach’s α ranging from .89 to .92 for the full symptom scale, and .78 to .84 across intrusion, avoidance, and hyperarousal subscales) and robust test-retest reliability across 2-to-3-week intervals (r = .83 for symptom severity, κ = .74 for diagnostic status). Criterion, convergent, and discriminant validities have been corroborated against structured clinical interviews, notably the Clinician-Administered PTSD Scale (CAPS) and the Structured Clinical Interview for DSM-IV (SCID), yielding diagnostic concordance rates between 82% and 89%, sensitivity figures between .82 and .89, and specificity exceeding .75. Confirmatory factor analyses have illuminated its structural architecture, demonstrating compatibility with both the classical DSM-IV three-factor model and modern four-factor models (e.g., the King et al. emotional numbing model and the Simms et al. dysphoria model). Completed in 10 to 15 minutes and requiring an approximate 8th-grade reading level (reading age of approximately 13 years), the PDS represents an invaluable clinical and epidemiological measurement standard.

2. Keywords

Posttraumatic Diagnostic Scale, PDS, Posttraumatic Stress Disorder, PTSD, Edna B. Foa, DSM-IV Criteria, Trauma Assessment, Psychometrics, Symptom Severity, Functional Impairment, Intrusive Thoughts, Avoidance, Hyperarousal

3. Authors

The Posttraumatic Diagnostic Scale was developed and validated by a distinguished research team at the Center for the Treatment and Study of Anxiety (CTSA), Department of Psychiatry, University of Pennsylvania School of Medicine:

• Edna B. Foa, Ph.D. — Professor of Clinical Psychology in Psychiatry and Director of the Center for the Treatment and Study of Anxiety, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States. Dr. Foa is globally recognized for her pioneering work in Prolonged Exposure Therapy and the experimental psychopathology of anxiety and trauma-related disorders.
• Leah Cashman, M.A. — Clinical Research Associate, Center for the Treatment and Study of Anxiety, Medical College of Pennsylvania and Hahnemann University / University of Pennsylvania.
• Lisa H. Jaycox, Ph.D. — Clinical Psychologist and Senior Behavioral Scientist at the RAND Corporation, formerly with the Center for the Treatment and Study of Anxiety, University of Pennsylvania.
• Katrina Perry, B.A. — Research Project Coordinator, Center for the Treatment and Study of Anxiety, Department of Psychiatry, University of Pennsylvania.

The preliminary precursor instrument, the PTSD Symptom Scale (PSS; Foa, Riggs, Dancu, & Rothbaum, 1993), was authored by Edna B. Foa, David S. Riggs, Constance V. Dancu, and Barbara Olasov Rothbaum, which laid the operational psychometric foundation for the standardized commercial publication of the PDS manual with National Computer Systems (NCS Pearson) in 1995.

4. Purpose

The primary clinical and scientific purpose of the Posttraumatic Diagnostic Scale is to provide a standardized, time-efficient, self-administered mechanism for systematically identifying exposure to potentially traumatic events, evaluating the cardinal diagnostic criteria of Posttraumatic Stress Disorder as defined by psychiatric nomenclature, and quantifying symptom severity alongside psychosocial functional impairment. Prior to the formal introduction of the PDS, clinicians and behavioral researchers frequently faced a challenging methodological dichotomy: they had to rely either on extensive, resource-heavy clinician-administered interviews such as the Clinician-Administered PTSD Scale (CAPS) or the Structured Clinical Interview for DSM (SCID), which necessitate doctoral-level training and up to 60 minutes per administration, or on abbreviated self-report questionnaires that assessed generic posttraumatic distress (such as the Impact of Event Scale) without aligning directly with official diagnostic thresholds.

The PDS bridges this operational gap by operationalizing all diagnostic dimensions of PTSD in strict adherence to the DSM-IV framework:

• Criterion A Verification: Evaluating whether an individual has been exposed to a qualifying traumatic stressor (Criterion A1: threat of death, serious injury, or violation of physical integrity) and experienced subjective emotional horror, terror, or helplessness at the peri-trauma stage (Criterion A2).
• Symptom Frequency and Dimensional Severity: Quantifying the monthly recurrence frequency of the 17 core posttraumatic manifestations, distributed across Re-experiencing / Intrusion (Criterion B), Avoidance and Emotional Numbing (Criterion C), and Increased Physiological Arousal (Criterion D).
• Chronicity and Duration: Gauging symptom stability, persistence, and presence for greater than one month (Criterion E).
• Functional and Psychosocial Impairment: Documenting the degree to which posttraumatic symptomatology disrupts essential occupational, educational, familial, interpersonal, and daily living obligations (Criterion F).

In clinical research, the PDS functions as an established outcome metric for randomized controlled trials (RCTs) examining pharmacotherapies (such as selective serotonin reuptake inhibitors) and empirically supported psychotherapies, including Prolonged Exposure (PE), Cognitive Processing Therapy (CPT), and Eye Movement Desensitization and Reprocessing (EMDR). In tertiary medical settings, community outpatient clinics, and emergency psychological services, it operates as a triage screening tool that can be completed by patients in 10 to 15 minutes and scored in under five minutes, reliably identifying individuals who warrant immediate, comprehensive trauma-focused intervention.

5. Psychological Construct

The psychological construct assessed by the PDS is Posttraumatic Stress Disorder conceptualized as a multi-component trauma reaction characterized by persistent psychological re-experiencing, pervasive behavioral avoidance, cognitive-emotional numbing, and heightened neurovegetative arousal resulting from exposure to life-threatening or deeply horrifying events. The PDS decomposes this multifaceted clinical construct into four distinct structural parts:

Part 1: Traumatic Event Inventory (Criterion A1 Exposure)

Trauma exposure constitutes the indispensable etiological gateway for posttraumatic psychopathology. The PDS presents a structured checklist comprising 12 distinct event categories, surveying direct personal experience and witness exposure to natural catastrophes, severe vehicular accidents, structure fires, nonsexual assaults by acquaintances or strangers, sexual assaults by known or unknown perpetrators, combat/war zones, childhood sexual abuse, physical torture, unlawful imprisonment, and life-threatening medical crises, complemented by an open-ended “Other” category. This section captures cumulative trauma history, recognizing that poly-victimization and multi-trauma exposure drastically elevate clinical vulnerability.

Part 2: Index Trauma Characteristics and Peri-Traumatic Emotionality (Criterion A1 and A2)

Because individuals frequently experience multiple traumas over a lifetime, posttraumatic symptomatology must be anchored to a specific reference event to maintain construct validity. Part 2 prompts the respondent to designate which trauma has disturbed them most in the preceding month and provide a qualitative narrative. It subsequently examines peri-traumatic physical injury (to self or others), perceived mortality threat, and the elicitation of severe peri-traumatic terror, horror, or helplessness (Criterion A2), verifying that the index trauma meets the rigorous clinical definition of an operational stressor.

Part 3: The Tripartite Core PTSD Symptom Dimensions

The core clinical architecture of the PDS comprises 17 items scored along a 4-point temporal frequency scale (0 to 3), mirroring the classic tripartite diagnostic structure:

• Re-experiencing / Intrusion (Criterion B; Items 1–5): Captures involuntary, unbidden intrusions of trauma memories into conscious awareness. This includes repetitive intrusive thoughts and mental imagery, harrowing recurrent nightmares, dissociative flashback reactions and illusions of event recurrence, intense subjective distress upon encountering internal or external trauma cues, and pronounced physiological reactivity (e.g., diaphoresis, tachycardia, muscular tremors) upon exposure to reminders.
• Avoidance and Emotional Numbing (Criterion C; Items 6–12): Reflects dual defensive and inhibitory psychological mechanisms. Items 6 and 7 gauge active cognitive avoidance (striving to suppress trauma-related thoughts, recollections, and feelings) and behavioral avoidance (evading physical environments, conversations, activities, or individuals evocative of the trauma). Items 8 through 12 measure posttraumatic emotional numbing and cognitive deficits, including psychogenic amnesia (inability to recall critical aspects of the trauma), profound anhedonia, pervasive feelings of alienation and detachment from others, affective flattening or emotional anesthesia (inability to experience loving feelings or weep), and a foreshortened sense of personal future.
• Hyperarousal (Criterion D; Items 13–17): Assesses sustained neurovegetative and psychomotor hyper-reactivity stemming from autonomic dysregulation. This includes sleep onset and maintenance insomnia, irritability and sudden explosive anger outbursts, executive concentration difficulties, hypervigilance (chronic visual scanning of the environment, postural alertness, avoiding backs to exits), and exaggerated acoustic or tactile startle responses.

Part 4: Functional Impairment (Criterion F)

To differentiate subclinical posttraumatic distress from a diagnosable psychiatric pathology, the construct requires demonstrable psychosocial functional interference. Part 4 assesses dichotomous (Yes/No) disruption across nine crucial ecological domains: work performance, domestic/household obligations, friendship networks, family relationships, recreational and leisure engagement, schoolwork/education, sexual intimacy, subjective global life satisfaction, and overall daily operational functioning.

6. Theoretical Framework

The Posttraumatic Diagnostic Scale is theoretically rooted in cognitive-behavioral paradigms of posttraumatic stress, most notably the Emotional Processing Theory (EPT) articulated by Edna B. Foa and Michael J. Kozak (1986), alongside subsequent refinements by Foa and David S. Riggs (1993). Under the EPT framework, posttraumatic psychopathology is conceptualized as an aberrant, rigid memory network stored in long-term memory that functions as a pathological “fear structure.”

A cognitive fear structure comprises three interconnected categories of mental representations:

1. Stimulus information regarding the traumatic event (e.g., sights, auditory cues, olfactory stimuli, ambient lighting).
2. Response information representing verbal, physiological, and behavioral reactions to the event (e.g., rapid heart rate, crying, muscle freezing, frantic attempts to escape).
3. Meaning elements that link stimulus cues with dangerous response outcomes and catastrophic personal appraisals (e.g., “the world is utterly malevolent,” “I am completely incompetent and fragile”).

In individuals who develop PTSD, this fear structure is characterized by an exceptionally low activation threshold, expansive stimulus generalization, and maladaptive cognitive associations. Neutral or benign stimuli (e.g., the scent of diesel fuel, a sudden ambient noise, an approaching stranger) trigger automatic activation of the entire fear network, precipitating intense subjective distress and physiological hyperarousal as if the trauma were recurring in real time. Because these intrusive re-experiencing episodes (Part 3, Items 1–5) are intensely aversive, the affected individual systematically deploys cognitive suppression and behavioral avoidance strategies (Part 3, Items 6–7). Paradoxically, avoidance precludes corrective information from entering the fear network, preventing the emotional processing necessary for natural extinction and cognitive restructuring. Furthermore, the persistent neurobiological state of hyperarousal (Part 3, Items 13–17) depletes self-regulatory cognitive resources, fueling emotional numbing, anhedonia, and social estrangement (Part 3, Items 8–12).

The PDS operationalizes these theoretical tenets by tracking the precise behavioral and affective manifestations of fear structure activation (intrusion and hyperarousal) alongside the respondent’s coping and defensive responses (avoidance and numbing). By anchoring these symptoms to a specific index event, the instrument directly captures the activation of trauma-specific memory nodes and their pervasive secondary impact on daily functioning.

7. Validity

The psychometric validity of the Posttraumatic Diagnostic Scale has been rigorously documented across numerous clinical, veteran, emergency-department, and community populations:

Criterion and Diagnostic Validity

In the seminal validation study by Foa, Cashman, Jaycox, and Perry (1997), the diagnostic accuracy of the PDS was evaluated against the gold-standard semi-structured interview, the Structured Clinical Interview for DSM-IV (SCID), in a heterogeneous sample of 248 trauma survivors (including victims of motor vehicle crashes, sexual assault, and nonsexual violent crime). The findings demonstrated:

• Overall Diagnostic Agreement: 82% concordance between the PDS categorical diagnosis and the SCID PTSD diagnostic classification (κ = .65, indicating substantial diagnostic agreement).
• Sensitivity: .89, indicating that the PDS correctly identified 89% of individuals with clinician-confirmed PTSD.
• Specificity: .75, reflecting a solid capacity to correctly rule out PTSD in non-affected trauma survivors.
• Positive Predictive Value (PPV): .80; Negative Predictive Value (NPV): .87.

Subsequent multi-site investigations evaluating the PDS against the Clinician-Administered PTSD Scale (CAPS) reported diagnostic concordances ranging from 84% to 89%, with area under the receiver operating characteristic curve (AUC-ROC) values consistently exceeding .88, confirming its exceptional criterion validity.

Convergent and Discriminant Validity

Convergent validity has been repeatedly corroborated through strong, statistically significant correlations with other validated measures of trauma distress and psychological morbidity:

• Correlation with the Impact of Event Scale (IES) total score: r = .78 to .85 (p < .001).
• Correlation with the Beck Depression Inventory (BDI): r = .70 to .79, reflecting the established theoretical and clinical comorbidity between posttraumatic stress and secondary depressive affect.
• Correlation with the State-Trait Anxiety Inventory (STAI-State): r = .68 to .74.

Discriminant validity is evidenced by significantly weaker correlations between the PDS Symptom Severity Score and instruments measuring conceptually dissimilar constructs, such as generalized somatic complaints, hypochondriasis, and unrelated personality scales (typically r < .30), confirming that the instrument captures trauma-induced distress rather than general diffuse negative affectivity.

8. Reliability

The PDS demonstrates exceptional psychometric reliability across internal consistency, item-total correlations, and temporal stability:

Internal Consistency

Across validation cohorts, the internal consistency of the 17-item symptom severity scale has proven consistently high. In the original cohort evaluated by Foa et al. (1997), Cronbach’s alpha for the total symptom scale was α = .92. Analysis of the individual symptom subscales yielded robust reliability estimates:

• Re-experiencing / Intrusion Subscale (Items 1–5): Cronbach’s α = .78 to .85
• Avoidance / Numbing Subscale (Items 6–12): Cronbach’s α = .82 to .86
• Hyperarousal Subscale (Items 13–17): Cronbach’s α = .82 to .87

Corrected item-total correlations across all 17 items consistently exceed .45, ranging from .48 to .73, confirming strong functional homogeneity among items.

Test-Retest Stability

Temporal stability was evaluated by administering the PDS twice to chronic, unmedicated trauma survivors across an elapsed interval of two to three weeks (Foa et al., 1997). Test-retest reliability for the continuous Symptom Severity Score reached a Pearson product-moment coefficient of r = .83 (p < .001). For categorical diagnostic determination (PTSD present vs. absent), test-retest concordance yielded a kappa coefficient of κ = .74, indicating substantial temporal consistency. Individual subscales demonstrated solid stability across time: Intrusion (r = .77), Avoidance/Numbing (r = .81), and Hyperarousal (r = .85).

9. Factor Analysis

The structural dimensionality of the 17 core items of the PDS has been the subject of comprehensive factor analytic scrutiny, encompassing both exploratory factor analysis (EFA) and confirmatory factor analysis (CFA):

The Traditional DSM-IV Three-Factor Architecture

Initial exploratory factor analyses conducted during test construction substantiated a three-factor solution aligning with DSM-IV criteria:

• Factor 1 (Intrusions / Re-experiencing): Marked by high primary factor loadings (> .55) on Items 1 through 5, with Item 4 (emotional reactivity to reminders) and Item 5 (physiological reactivity) demonstrating the highest factor coefficients (.68–.78).
• Factor 2 (Avoidance / Emotional Numbing): Items 6 through 12 loaded significantly on this broad defensive dimension, though secondary analyses early on indicated mild heterogeneity between active effortful avoidance (Items 6–7) and emotional blunting/numbing (Items 8–12).
• Factor 3 (Hyperarousal): Items 13 through 17 loaded cohesively, with Items 16 (hypervigilance) and 17 (exaggerated startle) exhibiting clean structural loadings exceeding .65.

Alternative Four-Factor Structural Models

With the evolution of latent structural modeling in psychotraumatology, subsequent CFA studies evaluated the PDS against competing structural models:

1. The King et al. (1998) Emotional Numbing Model: Divides DSM-IV Criterion C into two distinct factors: Effortful Avoidance (Items 6–7) and Emotional Numbing (Items 8–12), resulting in four latent factors: Re-experiencing, Avoidance, Numbing, and Hyperarousal. In multiple large-scale CFA investigations, this four-factor model demonstrated superior goodness-of-fit indices relative to the three-factor model (χ²/df < 2.5, Comparative Fit Index [CFI] > .94, Root Mean Square Error of Approximation [RMSEA] < .06).
2. The Simms et al. (2002) Dysphoria Model: Re-allocates non-specific distress symptoms across numbing and hyperarousal (Items 8–15: amnesia, anhedonia, detachment, restricted affect, foreshortened future, sleep disturbance, irritability, concentration difficulties) into a broad latent construct termed Dysphoria, alongside distinct factors for Intrusion (Items 1–5), Avoidance (Items 6–7), and Anxious Arousal (Items 16–17). Both the King et al. and Simms et al. models yield excellent structural fit, highlighting that the PDS effectively captures both trauma-specific fear-conditioned responses and generalized dysphoric neurovegetative distress.

10. Instrument / Measurement Tool

The Posttraumatic Diagnostic Scale is structured as follows:

• Assessment Type: Self-report psychological questionnaire.
• Target Population: Adolescents and adults (ages 13 and older) who have been exposed to one or more traumatic events.
• Reading Level: Approximately 8th-grade reading level (reading age ∼13 years).
• Completion Time: 10 to 15 minutes.
• Scoring Time: Approximately 5 minutes for manual hand scoring; instantaneous via authorized computerized scoring platforms.
• Number of Inquiries: 49 total operational inquiries across four distinct sections:
• Part 1 (Trauma Checklist): 12 event categories (11 specific types plus 1 open-ended category).
• Part 2 (Index Trauma Description and Criterion A Verification): Narrative text prompt plus 4 dichotomous (Yes/No) questions assessing physical injury, mortal danger, and feelings of terror/helplessness.
• Part 3 (PTSD Symptom Frequency Scale): 17 items corresponding to DSM-IV criteria B, C, and D, rated on a 4-point temporal frequency scale (0 to 3).
• Part 4 (Functional Impairment): 9 life areas rated dichotomously (Yes/No).
• Response Format for Core Symptom Items (Part 3):
  • 0 = Not at all or only one time (Once in a while / Once a week or less)
  • 1 = Once a week or less / Some of the time (2 times / week)
  • 2 = 2 to 4 times a week / Half the time (3 – 4 times / week)
  • 3 = 5 or more times a week / Almost always (5+ times / week)
• Continuous Symptom Severity Score: Calculated by summing the response weights (0 to 3) across the 17 core symptom items (Items 1–17 of Part 3). The score ranges from 0 to 51.
  • ≤ 10: Mild symptom severity
  • 11 – 20: Moderate symptom severity
  • 21 – 35: Moderate-to-severe symptom severity
  • ≥ 36: Severe symptom severity
• Number of Endorsed Symptoms: Sum of all items among the 17 core symptoms endorsed at a clinically significant frequency (defined as a rating ≥ 1, representing occurrence at least once per week). Score range: 0 to 17.
• Categorical Diagnostic Algorithm: A positive provisional diagnosis of PTSD requires satisfying all six DSM-IV criteria:
  1. Criterion A: Endorsement of an index trauma involving threat of death, injury, or physical violation, coupled with affirmative responses (“Yes”) indicating perceived life danger/injury and peri-traumatic helplessness or terror.
  2. Criterion B (Re-experiencing): Endorsement of at least 1 re-experiencing symptom (out of Items 1–5) rated ≥ 1.
  3. Criterion C (Avoidance and Numbing): Endorsement of at least 3 avoidance/numbing symptoms (out of Items 6–12) rated ≥ 1.
  4. Criterion D (Hyperarousal): Endorsement of at least 2 hyperarousal symptoms (out of Items 13–17) rated ≥ 1.
  5. Criterion E (Duration): Symptom duration exceeding one month (inherent in the 1-month reporting window).
  6. Criterion F (Impairment): Endorsement of “Yes” to at least 1 of the 9 functional impairment domains.

11. Permissions & Fee and Test Year

The Posttraumatic Diagnostic Scale was formally validated and published in 1997 by Edna B. Foa and colleagues, following the release of its commercial manual in 1995:

• Primary Developer: Edna B. Foa, Ph.D., Center for the Treatment and Study of Anxiety, University of Pennsylvania.
• Publisher & Commercial Rights: The original commercial pencil-and-paper forms and automated scoring software were published and distributed by National Computer Systems, Inc. (now Pearson Assessments).
• Licensing and Academic Use: While copyrighted commercial test booklets and computerized scoring platforms are marketed by Pearson, the scale items and structure have been published in peer-reviewed scientific journals (e.g., Psychological Assessment, 1997, Vol. 9, No. 4, pp. 445–451) and academic dissertations. Researchers seeking to utilize the scale for non-commercial scholarly research, university theses, or public health grant investigations should consult institutional library repositories, contact the developer’s academic center, or secure appropriate permissions through the commercial test distributor.
• Successor Version: Following the release of the DSM-5 in 2013, an updated edition titled the Posttraumatic Diagnostic Scale for DSM-5 (PDS-5) was developed and validated (Foa et al., 2016) to align with the revised four-cluster diagnostic framework. The classic PDS remains a historical psychometric benchmark and is actively referenced in long-term longitudinal studies.

12. References

The following foundational sources and peer-reviewed studies establish the empirical and psychometric validity of the Posttraumatic Diagnostic Scale:

• American Psychiatric Association. (1994). Diagnostic and statistical manual of mental disorders (4th ed.). American Psychiatric Association. https://doi.org/10.1176/appi.books.9780890423349
• Foa, E. B. (1995). Posttraumatic Stress Diagnostic Scale manual. National Computer Systems, Inc.
• Foa, E. B., Cashman, L., Jaycox, L., & Perry, K. (1997). The validation of a self-report measure of posttraumatic stress disorder: The Posttraumatic Diagnostic Scale. Psychological Assessment, 9(4), 445–451. https://doi.org/10.1037/1040-3590.9.4.445
• Foa, E. B., & Kozak, M. J. (1986). Emotional processing of fear: Exposure to corrective information. Psychological Bulletin, 99(1), 20–35. https://doi.org/10.1037/0033-2909.9.1.20
• Foa, E. B., McLean, C. P., Zang, Y., Rosenfield, D., Yadin, E., Yarvis, J. S., Mintz, J., Young-McCaughan, S., Borah, E. V., Dondanville, K. A., Fina, B. V., Hall-Clark, B. N., Lichtenstein, R., Litz, B. T., Roache, J. D., Wright, E. C., & Peterson, A. L. (2016). Psychometric properties of the Posttraumatic Diagnostic Scale for DSM-5 (PDS-5) in trauma-exposed military service members. Journal of Anxiety Disorders, 41, 142–146. https://doi.org/10.1016/j.janxdis.2016.05.006
• Foa, E. B., & Riggs, D. S. (1993). Post-traumatic stress disorder in rape victims. In J. Oldham, M. B. Riba, & A. Tasman (Eds.), American Psychiatric Press review of psychiatry (Vol. 12, pp. 273–303). American Psychiatric Press.
• Foa, E. B., Riggs, D. S., Dancu, C. V., & Rothbaum, B. O. (1993). Reliability and validity of a brief instrument for assessing post-traumatic stress disorder. Journal of Traumatic Stress, 6(4), 459–473. https://doi.org/10.1002/jts.2490060405
• King, D. W., Leskin, G. A., King, L. A., & Weathers, F. W. (1998). Confirmatory factor analysis of the Clinician-Administered PTSD Scale: Evidence for the dimensionality of posttraumatic stress disorder. Psychological Assessment, 10(2), 90–96. https://doi.org/10.1037/1040-3590.10.2.90
• Simms, L. J., Watson, D., & Doebbeling, B. N. (2002). Confirmatory factor analyses of posttraumatic stress disorder symptoms in deployed and nondeployed veterans of the Gulf War. Journal of Abnormal Psychology, 111(4), 637–647. https://doi.org/10.1037/0021-843X.111.4.637
• Swinbourne, J. M. (2009). The comorbidity between eating disorders and anxiety disorders (Doctoral dissertation, University of Sydney). Sydney eScholarship Repository. http://ses.library.usyd.edu.au/bitstream/2123/4026/1/j-swinbourne-thesis.pdf

13. Items of the Scale (Questionnaire)