International Trauma Questionnaire (ITQ)

Abstract

The International Trauma Questionnaire (ITQ) is an internationally validated, 18-item self-report diagnostic instrument specifically developed to operationalize the World Health Organization’s (WHO) 11th revision of the International Classification of Diseases (ICD-11) diagnostic criteria for Post-Traumatic Stress Disorder (PTSD) and Complex Post-Traumatic Stress Disorder (CPTSD). Conceptualized to establish a parsimonious, cross-culturally applicable, and clinically actionable measurement system, the ITQ bifurcates post-traumatic psychopathology into two distinct yet interrelated latent constructs: core PTSD (comprising the symptom clusters of Re-experiencing in the here and now, Avoidance of traumatic reminders, and a persistent Sense of current threat) and Disturbances in Self-Organization (DSO; comprising Affective Dysregulation, Negative Self-Concept, and Disturbances in Relationships). Each core symptom domain is assessed via two symptom indicators paired with three domain-specific functional impairment items evaluated across social, occupational, and broader life dimensions. Items are scored on a five-point Likert scale ranging from 0 (“Not at all”) to 4 (“Extremely”). Psychometric evaluations across diverse clinical, community, and epidemiological cohorts across the globe demonstrate robust internal consistency (Cronbach’s alpha and McDonald’s omega typically ranging between .79 and .94 across subscales), robust test-retest reliability, strict measurement invariance across gender and cultural contexts, and distinct discriminant validity separating CPTSD from comorbid conditions such as borderline personality disorder, major depressive disorder, and generalized anxiety disorder. The instrument operates via a validated categorical diagnostic algorithm while permitting dimensional symptom severity quantification, serving as the gold-standard diagnostic metric in contemporary traumatic stress research and clinical practice.

Keywords

International Trauma Questionnaire, ITQ, ICD-11, Post-Traumatic Stress Disorder, Complex PTSD, Disturbances in Self-Organization, Psychometrics, Factor Analysis, Trauma Measurement, Affect Dysregulation

Authors

The International Trauma Questionnaire was developed by an international consortium of psychometricians, clinical psychologists, and psychiatric researchers closely affiliated with the WHO ICD-11 Working Group on the Classification of Disorders Specifically Associated with Stress:

• Marylene Cloitre, Ph.D. — National Center for PTSD, Veterans Affairs Palo Alto Health Care System, Palo Alto, California, USA; Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine; and Department of Child and Adolescent Psychiatry, New York University Grossman School of Medicine.
• Mark Shevlin, Ph.D. — School of Psychology, Ulster University, Derry, Northern Ireland, United Kingdom.
• Chris R. Brewin, Ph.D. — Clinical, Educational & Health Psychology, Division of Psychology & Language Sciences, University College London, London, United Kingdom.
• Jonathan I. Bisson, DM, FRCPsych — Division of Psychological Medicine and Clinical Neurosciences, School of Medicine, Cardiff University, Cardiff, Wales, United Kingdom.
• Neil P. Roberts, D.Clin.Psy. — Psychology Directorate, Cardiff and Vale University Health Board, and Division of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff, United Kingdom.
• Andreas Maercker, M.D., Ph.D. — Department of Psychology, Division of Psychopathology and Clinical Intervention, University of Zurich, Zurich, Switzerland.
• Thanos Karatzias, Ph.D. — School of Health & Social Care, Edinburgh Napier University, Edinburgh, Scotland, United Kingdom; and The Rivers Centre for Traumatic Stress, NHS Lothian, Edinburgh, United Kingdom.
• Philip Hyland, Ph.D. — Department of Psychology, Maynooth University, Kildare, Ireland; and School of Psychology, National College of Ireland, Dublin, Ireland.

Purpose

The primary purpose of the International Trauma Questionnaire (ITQ) is to provide an empirical, standardized, and clinically viable operationalization of the diagnostic architecture set forth in the ICD-11 for trauma-related psychopathology. Prior to the release of the ICD-11, psychiatric nosology—predominantly governed by the American Psychiatric Association’s (APA) Diagnostic and Statistical Manual of Mental Disorders (DSM-5)—subsumed an increasingly broad array of cognitive, emotional, and physiological symptoms under a single, heterogeneous PTSD rubric consisting of 20 distinct symptoms spread across four clusters. This diagnostic expansion elevated clinical heterogeneity, resulting in hundreds of thousands of permissible symptom combinations capable of satisfying the diagnostic threshold for PTSD.

In direct contrast, the WHO ICD-11 diagnostic advisory committees pursued a philosophy of clinical utility, focusing on diagnostic parsimony, cross-cultural generalizability, and the reduction of diagnostic comorbidity. The WHO proposed a conceptual differentiation between two sister diagnoses: uncomplicated Post-Traumatic Stress Disorder (PTSD) and Complex Post-Traumatic Stress Disorder (CPTSD). Under this framework, PTSD captures fear-conditioned neurobiological responses directly anchored to traumatic stressors, while CPTSD captures this fear-based profile plus pervasive, enduring systemic alterations in personality and affective functioning—designated as Disturbances in Self-Organization (DSO)—frequently arising from sustained, repeated, or developmentally early interpersonal trauma (such as childhood physical or sexual abuse, domestic captivity, or prolonged torture).

The ITQ was engineered to address several distinct objectives in research and clinical environments:

• Categorical Diagnostic Classification: To definitively ascertain whether an individual satisfies the clinical threshold for ICD-11 PTSD or ICD-11 CPTSD based on an empirically validated diagnostic algorithm that preserves the hierarchical rule: an individual may meet criteria for PTSD or CPTSD, but never both simultaneously.
• Dimensional Severity Measurement: To permit the longitudinal quantification of symptom severity across the six individual subscales (Re-experiencing, Avoidance, Sense of Threat, Affective Dysregulation, Negative Self-Concept, and Relational Disturbances), facilitating treatment monitoring, outcome tracking, and psychotherapeutic efficacy evaluations.
• Differential Diagnosis and Comorbidity Reduction: To systematically disentangle genuine trauma-related self-organization disturbances from overlapping conditions, such as borderline personality disorder, major depressive disorder, and generalized anxiety states.
• Cross-Cultural and Low-Resource Utility: To deploy a streamlined, freely accessible instrument translated and validated across more than 30 languages, usable in low-resource epidemiological settings, refugee and humanitarian contexts, and advanced psychiatric clinics alike.

Psychological Construct

The ITQ is organized around two overarching second-order psychological constructs: Post-Traumatic Stress Disorder (PTSD) and Disturbances in Self-Organization (DSO). Together, these two higher-order dimensions subsume six first-order symptom clusters, each assessed via two dedicated symptom indicators paired with three items evaluating functional impairment across distinct spheres of daily living.

1. Post-Traumatic Stress Disorder (PTSD)

The ICD-11 PTSD construct reflects core conditioned trauma responses. Unlike DSM-5, which includes broad dysphoric and cognitive manifestations, the ICD-11 model focuses strictly on core post-traumatic symptoms:

• Re-experiencing in the Here and Now (Items 1 and 2): This construct captures trauma-related intrusions accompanied by vivid sensory re-living rather than passive cognitive recollection. Re-experiencing requires that intrusions possess an authentic temporal presence, wherein the traumatic event is perceived as actively recurring in the present moment. This is operationalized through vivid, terrifying nightmares (Item 1) and waking flashbacks, intrusive dissociative imagery, or full-scale illusions that bypass executive inhibition (Item 2).
• Avoidance of Reminders (Items 3 and 4): Avoidance represents deliberate behavioral or cognitive strategies executed to evade stimuli linked to the trauma. The construct delineates internal avoidance—the suppression of distressing trauma-related thoughts, distressing mental imagery, or visceral somatic sensations (Item 3)—and external avoidance—the deliberate circumvention of people, environmental locations, conversations, sensory cues, or activities that evoke traumatic recall (Item 4).
• Sense of Current Threat (Items 5 and 6): This construct operationalizes autonomic hyperarousal and persistent perceived danger uncoupled from objective safety conditions. It is characterized by hypervigilance, manifested as an enduring state of physiological and cognitive readiness, scanning environments for imminent peril (Item 5), and an exaggerated startle response, manifested as physiological jumpiness and somatic hyper-reactivity triggered by unexpected sensory stimuli (Item 6).

2. Disturbances in Self-Organization (DSO)

Disturbances in Self-Organization reflect pervasive, cross-situational disruptions in self-regulatory capacity, interpersonal functioning, and identity construction, typically arising from developmental or chronic, inescapable traumatic exposure:

• Affective Dysregulation (Items 10 and 11): This construct reflects neurobiological and emotional dysregulation across both hyper-reactive and hypo-reactive axes. Hyper-reactivity is operationalized as prolonged emotional recovery latency—an inability to regain emotional baseline following acute distress, marked by uncontrolled emotional outbursts, rage, or anxiety (Item 10). Hypo-reactivity, or emotional blunting, is operationalized as profound psychic numbing, affective detachment, and an inability to experience positive or negative emotions (Item 11).
• Negative Self-Concept (Items 12 and 13): In contrast to situational low self-esteem, this construct captures deep-seated, chronic, and pervasive beliefs of worthlessness, failure, self-contempt, and profound shame. It reflects an internalized identity damaged by trauma, where the individual defines themselves fundamentally as an irredeemable failure (Item 12) or as intrinsically worthless and contaminated (Item 13).
• Disturbances in Relationships (Items 14 and 15): This construct operationalizes persistent relational impairment characterized by relational avoidance, social detachment, and an inability to form or sustain emotional intimacy. Individuals report feeling profoundly disconnected or alienated from other human beings (Item 14) and experience enduring difficulty maintaining authentic emotional closeness, often due to deep mistrust, fear of betrayal, or affective exhaustion (Item 15).

3. Functional Impairment Dimensions (Items 7–9 and 16–18)

Both the PTSD and DSO components require evidence of functional impairment. The ITQ assesses three explicit domains: interpersonal/social life, occupational/work capacity, and other vital life spheres (such as parenting, education, or physical health). Functional impairment must be specifically attributed to the respective symptom clusters, cementing clinical significance.

Theoretical Framework

The structural and conceptual foundation of the ITQ is rooted in contemporary trauma psychology, developmental psychopathology, and the classification principles established by the WHO ICD-11 Working Group. Three major theoretical paradigms directly inform the design and clinical logic of the instrument:

1. Herman’s Paradigm of Complex Traumatization

The theoretical concept of CPTSD was introduced by Judith Lewis Herman (1992) in her seminal work on psychological trauma. Herman posited that traditional diagnostic formulations of PTSD were tailored to acute, circumscribed traumatic life events (such as motor vehicle accidents, natural disasters, or isolated assaults). She asserted that prolonged, repeated interpersonal captivity—such as childhood physical or sexual abuse, chronic domestic violence, concentration camp internment, or human trafficking—inflicts systemic damage on the victim’s underlying psychological architecture. This damage compromises affect regulation, identity formation, somatic integration, and interpersonal capacity. The ITQ operationalizes Herman’s conceptual framework into the three DSO clusters, translating dynamic clinical observations into an empirically measurable psychometric structure.

2. The WHO Philosophy of Clinical Utility and Diagnostic Parsimony

The International Advisory Group for the Revision of ICD-10 Mental and Behavioural Disorders, led by figures including Geoffrey Reed and Andreas Maercker, initiated a paradigm shift in psychiatric classification. They argued that psychiatric criteria must avoid excessive complexity, which burdens healthcare workers in primary care and low-resource settings. The ICD-11 prioritized clinical utility, defining disorders by their core features rather than attempting exhaustive compendiums of every possible symptom. By reducing PTSD to six core symptoms of fear conditioning and establishing CPTSD as a distinct diagnostic entity requiring the co-occurrence of PTSD and DSO, the WHO established a non-redundant, clinically intuitive classification system that the ITQ directly mirrors.

3. Cognitive and Neurobiological Models of Trauma Memory

The dual-representation theory of PTSD developed by Chris R. Brewin and colleagues provides the cognitive foundation for the ITQ’s Re-experiencing items. Brewin posits two distinct memory representations: verbally accessible memories (VAMs), which are integrated into autobiographical memory contexts, and situationally accessible memories (SAMs), which contain non-contextualized, lower-level sensory impressions triggered automatically by perceptual cues. The ITQ deliberately assesses SAM-based intrusion—flashbacks and nightmares characterized by a sensation of re-living the trauma in the “here and now”—excluding autobiographical, non-dissociative thoughts about the event.

Furthermore, contemporary attachment theory and polyvagal theory elucidate the DSO domains: early interpersonal trauma fractures the developing child’s relational template, leading to hyper-aroused or hypo-aroused nervous system responses (affective dysregulation), internal working models of the self as defective (negative self-concept), and systemic avoidance of proximity to others (relational disturbances).

Validity

The psychometric validity of the International Trauma Questionnaire has been extensively demonstrated in numerous cross-national studies, clinical validation trials, and large-scale epidemiological investigations.

Construct and Factorial Validity

Construct validity for the ITQ rests upon structural evidence that PTSD and CPTSD reflect distinct clinical profiles. In the definitive validation study conducted by Cloitre et al. (2018), confirmatory factor analysis (CFA) on clinical and community samples confirmed that a correlated two-factor higher-order model (PTSD and DSO) comprised of six first-order symptom factors yielded superior fit compared to single-factor or broad PTSD models. These results have been replicated across diverse language adaptations, including German, French, Spanish, Italian, Japanese, Chinese, Arabic, and Ukrainian cohorts, demonstrating the structural validity of the ICD-11 construct across cultures.

Convergent Validity

The ITQ demonstrates robust convergent validity with alternative validated trauma instruments and established psychological measures. The PTSD subscale correlates strongly with the PTSD Checklist for DSM-5 (PCL-5; $r = .75$ to $.86$) and the Impact of Event Scale-Revised (IES-R; $r = .72$ to $.81$). The DSO dimensions show high convergent associations with measures of emotion dysregulation (such as the Difficulties in Emotion Regulation Scale [DERS]; $r = .65$ to $.78$), chronic shame and low self-esteem (Rosenberg Self-Esteem Scale; $r = -.60$ to $-.72$), and interpersonal alienation (Inventory of Interpersonal Problems [IIP-32]; $r = .58$ to $.69$).

Discriminant and Criterion Validity

A crucial psychometric challenge in trauma nosology is distinguishing CPTSD from Borderline Personality Disorder (BPD). Multiple latent class analyses (LCA) and factor-analytic studies (e.g., Cloitre et al., 2014; Hyland et al., 2018) have demonstrated that the ITQ reliably differentiates CPTSD from BPD. While both conditions share emotional instability, BPD is characterized by fear of abandonment, suicidal behavior, and fluctuating identity disturbance, whereas CPTSD as measured by the ITQ is marked by enduring emotional blunting or prolonged recovery latencies, a consistently stable negative self-concept (pervasive worthlessness), and persistent relational avoidance rather than unstable, intense relational storms.

Predictive and Ecological Validity

The ITQ exhibits strong criterion and predictive validity regarding trauma etiology and functional disability. Studies consistently reveal that individuals meeting criteria for CPTSD on the ITQ report significantly higher frequencies of chronic, repeated, childhood-onset interpersonal trauma (such as physical abuse, sexual abuse, or neglect) compared to those meeting criteria for uncomplicated PTSD, whose trauma histories are more frequently single-incident or adult-onset. Furthermore, CPTSD diagnoses derived from the ITQ predict significantly greater functional impairment across occupational and interpersonal domains, higher psychiatric comorbidity, and greater healthcare service utilization.

Reliability

The ITQ has demonstrated high reliability across diverse research paradigms, clinical samples, and general population cohorts worldwide.

Internal Consistency

Internal consistency estimates across studies reflect strong scale reliability for both dimensional subscales and overarching factor scores. In standard validation studies (Cloitre et al., 2018; Karatzias et al., 2016, 2017; Hyland et al., 2017):

• Total ITQ Symptom Score: Cronbach’s $\alpha$ consistently ranges from $.89$ to $.94$; McDonald’s $\omega$ ranges from $.90$ to $.95$.
• PTSD Domain: Cronbach’s $\alpha$ ranges between $.81$ and $.89$; McDonald’s $\omega$ ranges between $.82$ and $.90$.
• DSO Domain: Cronbach’s $\alpha$ ranges between $.84$ and $.91$; McDonald’s $\omega$ ranges between $.85$ and $.92$.
• Individual Symptom Clusters:
  • Re-experiencing: Spearman-Brown split-half / inter-item correlation $r = .65$ to $.78$; $\alpha = .76$ to $.84$.
  • Avoidance: Inter-item correlation $r = .62$ to $.75$; $\alpha = .74$ to $.82$.
  • Sense of Threat: Inter-item correlation $r = .68$ to $.80$; $\alpha = .78$ to $.86$.
  • Affective Dysregulation: Inter-item correlation $r = .52$ to $.68$; $\alpha = .67$ to $.78$.
  • Negative Self-Concept: Inter-item correlation $r = .75$ to $.88$; $\alpha = .85$ to $.92$.
  • Disturbances in Relationships: Inter-item correlation $r = .70$ to $.82$; $\alpha = .81$ to $.88$.

Test-Retest Reliability

Evaluations of temporal stability across intervals ranging from two weeks to one month in stable clinical samples indicate high test-retest reliability. Intraclass correlation coefficients (ICCs) for the PTSD scale range from $.82$ to $.89$, and for the DSO scale from $.79$ to $.87$. Longitudinal test-retest reliability across non-treatment-seeking cohorts confirms that the ITQ reliably reflects persistent trauma symptomatology rather than temporary mood fluctuations.

Measurement Invariance

Extensive psychometric investigations have established multigroup measurement invariance across various sociodemographic variables. The ITQ exhibits configural, metric (weak), and scalar (strong) invariance across gender, age cohorts, trauma exposure profiles (e.g., combat veterans vs. civilian assault survivors), and cultural contexts. The establishment of scalar invariance confirms that mean score differences observed across demographic groups reflect true variations in latent trauma psychopathology rather than measurement bias.

Factor Analysis

The structural topology of the ITQ has been investigated using Exploratory Factor Analysis (EFA), Confirmatory Factor Analysis (CFA), and exploratory structural equation modeling (ESEM). These analyses consistently support the ICD-11 conceptual model.

Model Comparisons and Latent Structure

During the developmental psychometric validation (Cloitre et al., 2018), alternative structural models were formally tested using robust maximum likelihood (MLR) and weighted least squares mean and variance adjusted (WLSMV) estimation:

1. One-Factor Model: All 12 symptom items load onto a single undifferentiated post-traumatic distress factor. This model demonstrated poor fit across all indices: Comparative Fit Index (CFI) < .80, Tucker-Lewis Index (TLI) < .75, Root Mean Square Error of Approximation (RMSEA) > .12.
2. Two-Factor Model: Items load onto two correlated first-order factors representing general PTSD and general DSO. Fit improved but remained inadequate (CFI $\approx .87$, RMSEA $\approx .09$).
3. Six-Factor First-Order Model: Items load onto six correlated first-order factors (Re-experiencing, Avoidance, Sense of Threat, Affective Dysregulation, Negative Self-Concept, and Relational Disturbances). This model yielded excellent fit: $\chi^2 / \text{df} < 2.5$, $\text{CFI} > .97$, $\text{TLI} > .96$, $\text{RMSEA} < .045$ ($90%\text{ CI } [.035, .055]$).
4. Two-Factor Second-Order (Hierarchical) Model: The six first-order factors load onto two correlated second-order factors: PTSD (subsuming Re-experiencing, Avoidance, and Sense of Threat) and DSO (subsuming Affective Dysregulation, Negative Self-Concept, and Relational Disturbances). This theoretically driven model exhibited excellent statistical fit equivalent to the unconstrained six-factor solution ($\text{CFI} = .972$, $\text{TLI} = .965$, $\text{RMSEA} = .044$, $\text{SRMR} = .038$).

Standardized Factor Loadings

In the optimal second-order structural model, standardized factor loadings ($lambda$) are uniformly high and statistically significant ($p < .001$):

• PTSD First-Order Loadings:
  • Re-experiencing items load onto their latent factor at $lambda = .78$ (Item 1) and $lambda = .84$ (Item 2).
  • Avoidance items load at $lambda = .76$ (Item 3) and $lambda = .83$ (Item 4).
  • Sense of Threat items load at $lambda = .81$ (Item 5) and $lambda = .85$ (Item 6).
  • Second-order loadings of these three clusters onto the higher-order PTSD construct range from $.72$ to $.89$.
• DSO First-Order Loadings:
  • Affective Dysregulation items load at $lambda = .65$ (Item 10) and $lambda = .73$ (Item 11).
  • Negative Self-Concept items load at $lambda = .89$ (Item 12) and $lambda = .92$ (Item 13).
  • Disturbances in Relationships items load at $lambda = .82$ (Item 14) and $lambda = .86$ (Item 15).
  • Second-order loadings of these three clusters onto the higher-order DSO construct range from $.74$ to $.91$.

The correlation between the second-order latent PTSD factor and second-order latent DSO factor typically falls between $.55$ and $.70$, indicating that while the constructs share common trauma-related variance, they remain distinct latent entities.

Instrument / Measurement Tool

The International Trauma Questionnaire (ITQ) is structured as follows:

• Instrument Designation: International Trauma Questionnaire (ITQ).
• Constructs Measured: Post-Traumatic Stress Disorder (PTSD) and Complex Post-Traumatic Stress Disorder (CPTSD) according to ICD-11 criteria.
• Administration Format: Standardized self-report pencil-and-paper or digital questionnaire; can also be clinician-administered.
• Total Item Count: 18 items (6 PTSD symptom items, 3 PTSD functional impairment items, 6 DSO symptom items, and 3 DSO functional impairment items).
• Index Trauma Reference: The questionnaire begins with an identification of the respondent’s index trauma (the single most distressing traumatic experience), instructing the respondent to keep this experience in mind when answering symptoms.
• Timeframe / Recall Period: Symptoms are evaluated over the past month.
• Response Format: 5-point Likert scale:
  • 0 = Not at all
  • 1 = A little bit
  • 2 = Moderately
  • 3 = Quite a bit
  • 4 = Extremely
• Diagnostic Scoring Rules:
  • Symptom Endorsement Threshold: An individual item is considered clinically endorsed if the respondent selects a score of $ge 2$ (“Moderately”).
  • PTSD Criteria: Requires endorsement of at least one item from each of the three PTSD symptom clusters:
    • Re-experiencing: Item 1 or Item 2 $ge 2$
    • Avoidance: Item 3 or Item 4 $ge 2$
    • Sense of Threat: Item 5 or Item 6 $ge 2$
    • PTSD Functional Impairment: Endorsement (score $ge 2$) on at least one impairment item (Item 7, 8, or 9).
  • DSO Criteria: Requires endorsement of at least one item from each of the three DSO clusters:
    • Affective Dysregulation: Item 10 or Item 11 $ge 2$
    • Negative Self-Concept: Item 12 or Item 13 $ge 2$
    • Disturbances in Relationships: Item 14 or Item 15 $ge 2$
    • DSO Functional Impairment: Endorsement (score $ge 2$) on at least one impairment item (Item 16, 17, or 18).
  • Diagnostic Hierarchy / Assignment Rule:
    • If PTSD criteria are met AND DSO criteria are NOT met $\rightarrow$ Diagnosis: PTSD.
    • If PTSD criteria are met AND DSO criteria ARE met $\rightarrow$ Diagnosis: Complex PTSD (CPTSD).
    • Under ICD-11 rules, CPTSD supersedes PTSD. A patient cannot receive a comorbid diagnosis of both PTSD and CPTSD simultaneously.
  • Dimensional Scoring: Subscale scores can be derived by summing item scores within clusters:
    • PTSD Total Severity Score: Sum of Items 1 through 6 (range: 0–24).
    • DSO Total Severity Score: Sum of Items 10 through 15 (range: 0–24).
    • Overall CPTSD Severity Score: Sum of all 12 symptom items (range: 0–48).

Permissions & Fee and Test Year

The International Trauma Questionnaire was formally published in its validated format in 2018 by Cloitre, Shevlin, Brewin, Bisson, Roberts, Maercker, Karatzias, and Hyland in Acta Psychiatrica Scandinavica.

In alignment with the World Health Organization’s commitment to global mental health equity, the authors designated the ITQ as an Open Access psychometric instrument. The questionnaire is distributed under the terms of Creative Commons licensing, permitting free use for academic research, non-commercial clinical evaluation, epidemiological surveys, and educational purposes without payment of licensing fees or royalties. The instrument, alongside official translations in dozens of languages and detailed diagnostic scoring guides, is publicly accessible via the European Society for Traumatic Stress Studies (ESTSS) platform and the official ITQ repository (Trauma Measures Global). Commercial adaptation or software integration for commercial profit requires written authorization from the copyright holders.

References

• Brewin, C. R., Cloitre, M., Hyland, P., Shevlin, M., Maercker, A., Bryant, R. A., Humayun, A., Jones, L. M., Kaminer, D., Lobbestael, J., Medina-Mora, M. E., Somasundaram, D., Liang, C., & Reed, G. M. (2017). A review of PTSD and complex PTSD in ICD-11. Clinical Psychology Review, 58, 1–15. https://doi.org/10.1016/j.cpr.2017.09.001
• Cloitre, M., Garvert, D. W., Brewin, C. R., Bryant, R. A., & Maercker, A. (2013). Evidence for proposed ICD-11 PTSD and complex PTSD: A latent profile analysis. European Journal of Psychotraumatology, 4(1), 20706. https://doi.org/10.3402/ejpt.v4i0.20706
• Cloitre, M., Garvert, D. W., Weiss, B., Carlson, E. B., & Bryant, R. A. (2014). Distinguishing PTSD, Complex PTSD, and Borderline Personality Disorder: A latent class analysis. European Journal of Psychotraumatology, 5(1), 25097. https://doi.org/10.3402/ejpt.v5.25097
• Cloitre, M., Shevlin, M., Brewin, C. R., Bisson, J. I., Roberts, N. P., Maercker, A., Karatzias, T., & Hyland, P. (2018). The International Trauma Questionnaire: Development of a self-report measure of ICD-11 PTSD and complex PTSD. Acta Psychiatrica Scandinavica, 138(6), 536–546. https://doi.org/10.1111/acps.12956
• Herman, J. L. (1992). Complex PTSD: A syndrome in survivors of prolonged and repeated trauma. Journal of Traumatic Stress, 5(3), 377–391. https://doi.org/10.1002/jts.2490050305
• Hyland, P., Shevlin, M., Brewin, C. R., Cloitre, M., Downes, N., Jumbe, S., Karatzias, T., Bisson, J. I., & Roberts, N. P. (2017). Validation of post-traumatic stress disorder (PTSD) and complex PTSD using the International Trauma Questionnaire. Acta Psychiatrica Scandinavica, 136(3), 313–322. https://doi.org/10.1111/acps.12771
• Hyland, P., Karatzias, T., Shevlin, M., & Cloitre, M. (2018). Distinct clusters of trauma survivors: An empirical test of the ICD-11 proposals for PTSD and Complex PTSD. Social Psychiatry and Psychiatric Epidemiology, 53(6), 599–608. https://doi.org/10.1007/s00127-018-1510-z
• Karatzias, T., Shevlin, M., Fyvie, C., Hyland, P., Efthymiadou, E., Wilson, D., Roberts, N., Bisson, J. I., Brewin, C. R., & Cloitre, M. (2016). An initial psychometric evaluation of the ICD-11 draft diagnostic criteria for PTSD and Complex PTSD. Psychological Medicine, 46(6), 1271–1282. https://doi.org/10.1017/S0033291715002846
• Karatzias, T., Shevlin, M., Fyvie, C., Hyland, P., Efthymiadou, E., Wilson, D., Roberts, N. P., Bisson, J. I., Brewin, C. R., & Cloitre, M. (2017). Evidence of distinct profiles for ICD-11 post-traumatic stress disorder (PTSD) and complex post-traumatic stress disorder (CPTSD) based on the International Trauma Questionnaire. Journal of Affective Disorders, 207, 181–187. https://doi.org/10.1016/j.jad.2016.09.032
• Maercker, A., Brewin, C. R., Bryant, R. A., Cloitre, M., Reed, G. M., van Ommeren, M., Humayun, A., Jones, L. M., Kaminer, D., Llosa, A. E., Medina-Mora, M. E., Somasundaram, D., & Saxena, S. (2013). Proposals for mental disorders specifically associated with stress in the International Classification of Diseases-11. The Lancet, 381(9878), 1683–1685. https://doi.org/10.1016/S0140-6736(12)62191-6
• World Health Organization. (2018). International Classification of Diseases for Mortality and Morbidity Statistics (11th Revision). World Health Organization. https://icd.who.int/browse11/l-m/en

Items of the Scale