Development of the PTSD-iMPACT to Measure PTSD-Related Functional Impairment in Children and Adolescents - A Validation Study in Switzerland and Germany

The PTSD-iMPACT is designed to assess the severity of PTSD-related functional impairment across specific activities and tasks in multiple life domains.

The development of the PTSD-iMPACT followed a two-phase process. First, a systematic review was conducted to examine how existing PTSD-specific instruments, diagnostic interview modules, and general measures of functional impairment assess PTSD-related impairment in youth. The review revealed considerable heterogeneity in the domains assessed, frequent reliance on dichotomous response options, inconsistent scoring procedures, and a general lack of psychometric validation. Many instruments assessed functioning only at a global level, without capturing the specific nature or severity of difficulties within each domain. Furthermore, most relied on face validity and lacked demonstrated content validity, highlighting the need for a more methodologically sound tool.

In the second phase, qualitative interviews and focus groups were conducted (Cantonal Ethics Committee Zurich, Switzerland; BASEC-ID 2023-01290) with trauma-exposed children and adolescents (aged 7-18) who presented with at least moderate PTSS, as well as caregivers of children aged 1-18 with similar symptom profiles. Participants were recruited through clinical and social service settings. Data were analyzed using qualitative content analysis to identify relevant domains of functioning and specific challenges within those domains affected by PTSS. This conceptual framework informed item generation for the PTSD-iMPACT. Item refinement was carried out with input from clinical and research experts.

The final instrument includes both a self-report and caregiver-report version for children and adolescents aged 7-18, as well as a caregiver-version for children aged 3-6. It is designed to enhance clinical decision-making, improve diagnostic accuracy, and support outcome monitoring across diverse international contexts.

To ensure that the PTSD-iMPACT functions as a psychometrically sound and clinically meaningful assessment tool, validation across both clinical and non-clinical populations is essential and is therefore carried out in the present study. This process will allow for the evaluation of sensitivity, specificity, and broader applicability across varying levels of functional impairment, thereby supporting its use in both research and routine clinical practice.

The primary outcome will be the PTSD-iMPACT. The secondary outcomes for 7-18 year old children and adolescents include sociodemographic information, PTEs, PTSD, depression, anxiety, adjustment disorder, level of functioning, health-related quality of life, and regulation of emotional expression. The secondary outcomes for 3-6 year old children (caregiver-report) include sociodemographic information, PTEs, PTSD, depression, anxiety, oppositional behavior, adjustment disorder, stressor-related thoughts and worries, and health-related quality of life. Table 1 provides an overview of the constructs assessed and corresponding instruments used across participant groups.

Hypothesis and primary objective

The overall aim of this study is to evaluate the psychometric properties of the PTSD-iMPACT questionnaire in trauma-exposed children and adolescents. The specific aims of the present project are as follows:

1. To examine the reliability of the PTSD-iMPACT for children and adolescents aged 7 to 18 years. This includes the internal consistency of the self- and caregiver report, as well as the test-retest reliability of the PTSD-iMPACT, and the CATS-2 with a time span of two weeks.

Hypothesis 1a: Internal consistency: We assume that the items of the PTSD-iMPACT self-report (7-18y) positively correlate with each other, as well as the items of the PTSD-iMPACT caregiver report (7-18y).

Hypothesis 1b: Test-retest-reliability: We assume a positive correlation between the results of the first and second time of measurement of the PTSD-iMPACT (7-18y), as well as the CATS-2. 2. To examine the validity of the PTSD-iMPACT for children and adolescents aged 7 to 18 years, including the construct validity (convergent and divergent validity), the criterion validity (concurrent and predictive validity) and the factorial validity. Furthermore, we aim to determine an optimal cut-off value.

Hypothesis 2a: Construct validity: We assume stronger positive correlations between the PTSD-iMPACT (7-18y) and the PTSD-specific instrument CATS-2 compared to its correlations with measures of general emotional and behavioral problems (IDQ, IAQ). Additionally, we expect the KIDSCREEN-10, which measures health-related quality of life, to show negative correlations with PTSD-iMPACT (7-18y). While not a direct measure of functional impairment, it captures aspects of well-being that are likely influenced by PTSD-related difficulties in daily life.

Hypothesis 2b: Concurrent validity: We assume that the results of the PTSD-iMPACT (7-18y) positively correlate with the results of the Work and Social Adjustment Scale for Youth (WSAS-Y) and the universal 0-100 rating question "To what extent have the symptoms affected your child in daily life?".

Hypothesis 2c: Predictive validity: We hypothesize that results of the PTSD-iMPACT (7-18y) differ between individuals with a normal, moderate, elevated and high PTSD symptomatology.

Hypothesis 2d: Factorial validity: We assume that the theoretically and empirically derived structure of the PTSD-iMPACT (7-18y) is plausible (the factors reflect the subscales and the items of each subscale load onto their respective factors). 3. To examine the reliability of the PTSD-iMPACT for children aged 3 to 6 years. This includes the internal consistency of the caregiver report, as well as the test-retest reliability of the PTSD-iMPACT, and the CATS 3-6 with a time span of two weeks.

Hypothesis 3a: Internal consistency: We assume that the items of the PTSD-iMPACT self-report (3-6y) positively correlate with each other, as well as the items of the PTSD-iMPACT caregiver report (3-6y).

Hypothesis 3b: Test-retest-reliability: We assume a positive correlation between the results of the first and second time of measurement of the PTSD-iMPACT (3-6y), and the CATS 3-6 4. To examine the validity of the PTSD-iMPACT for children aged 3 to 6 years, including the construct validity (convergent and divergent validity), the criterion validity (concurrent and predictive validity) and the factorial validity. Furthermore, we aim to determine an optimal cut-off value.

Hypothesis 4a: Construct validity: We assume stronger positive correlations between the PTSD-iMPACT (3-6y) and the PTSD-specific instrument CATS 3-6, compared to the correlations between results of the PTSD-iMPACT (3-6y) and questionnaires assessing general emotional and behavioral problems (CBCL subscales: anxiety, depression, oppositional behavior). Additionally, we expect the Pediatric Quality of Life Inventory (PedsQL) \[22\], which measures health-related quality of life, to show negative correlations with PTSD-iMPACT.

Hypothesis 4b: Concurrent validity: We assume that the results of the PTSD-iMPACT negatively correlate with ad the universal 0-100 rating question "To what extent have the symptoms affected your child in daily life?".

Hypothesis 4c: Predictive validity: We hypothesize, that results of the PTSD-iMPACT (3-6y) differ between individuals with a normal, moderate, elevated and high PTSD symptomatology.

Hypothesis 4d: Factorial validity: We assume that the theoretically and empirically derived structure of the PTSD-iMPACT (3-6y) is plausible.

Statistics and Methodology

After the completion of data collection and prior to the statistical analysis of reliability and validity, a final integration of all measurement data from all participating centers will be conducted. Statistical analyses will be performed using R, SPSS and Mplus. All statistical analyses will be conducted using a two-sided significance level of α = 0.05. A minimum of 100 trauma-exposed participants per clinical cohort is deemed required.

Statistical analysis for the PTSD-iMPACT (7-18 years) validation

• Sample and items descriptives: Item description, item means, standard deviations, skewness, kurtosis, and range for both self- and caregiver report.

Reliability * Internal consistency: Cronbach's alpha and McDonald's omega for PTSD-iMPACT (self- and caregiver report). * Test-retest reliability: The Intraclass Correlation Coefficient (ICC) will be calculated for PTSD-iMPACT, and the CATS-2.

Validity

Construct Validity: * Convergent validity: Correlations with the PTSD-specific instrument CATS-2, and the health-related quality of life measure (KIDSCREEN-10). * Divergent validity: Correlations with questionnaires assessing general emotional and behavioral problems (IDQ, and IAQ).

Criterion Validity: * Concurrent validity: Correlations with the WSAS-Y. The universal 0-100 rating question will be used as an external criterion. * Predictive validity: Differentiation between individuals with a normal, moderate, elevated and high PTSD symptomatology (Mann-Whitney U test, Cohen's d). ROC analyses will be conducted to determine diagnostic accuracy (sensitivity, specificity). The optimal cut-off value will be determined using the Youden Index.

Factorial Validity:

• Confirmatory Factor Analysis (CFA): Examination of the theoretically and empirically derived structure of the questionnaire (subscales and item allocation). The CFA will assess whether the items load on the expected subscales, whether model fit indices are acceptable, and whether the correlations between factors are plausible.

Statistical analysis for the PTSD-iMPACT (3-6 years) validation

• Sample and items descriptives: Item description, item means, standard deviations, skewness, kurtosis, and range for caregiver-report.

Reliability * Internal consistency: Cronbach's alpha and McDonald's omega for PTSD-iMPACT (caregiver report). * Test-retest reliability: The Intraclass Correlation Coefficient (ICC) will be calculated for PTSD-iMPACT, and the CATS 3-6.

Validity

Construct Validity: * Convergent validity: Correlations with the PTSD-specific instrument CATS 3-6and the health-related quality of life measure (PedsQL). * Divergent validity: Correlations with questionnaires assessing general emotional and behavioral problems (CBCL subscales: anxiety, depression, oppositional behavior).

Criterion Validity: * Concurrent validity: Correlations with the PedsQL. The universal 0-100 rating question will be used as an external criterion. * Predictive validity: Differentiation between individuals with a normal, moderate, elevated and high PTSD symptomatology (Mann-Whitney U test, Cohen's d). ROC analyses will be conducted to determine diagnostic accuracy (sensitivity, specificity). The optimal cut-off value will be determined using the Youden Index.

Factorial Validity:

• Confirmatory Factor Analysis (CFA): Examination of the theoretically and empirically derived structure of the questionnaire (subscales and item allocation). The CFA will assess whether the items load on the expected subscales, whether model fit indices are acceptable, and whether the correlations between factors are plausible.

Handling of missing data

• Potentially traumatic events (PTE) (Children and adolescents aged 7 to 18 years) [Срок оценки: Baseline and Follow-up two weeks later. In nonclinical samples, data will be only assessed at Baseline.]
• PTSD (Children and adolescents aged 7 to 18 years) [Срок оценки: Baseline and Follow-up two weeks later. In nonclinical samples, data will be only assessed at Baseline.]
• Depression (Children and adolescents aged 7 to 18 years) [Срок оценки: Baseline]
• Anxiety (Children and adolescents aged 7 to 18 years) [Срок оценки: Baseline]
• Quality of life (Children and adolescents aged 7 to 18 years) [Срок оценки: Baseline]
• Functioning (Children and adolescents aged 7 to 18 years) [Срок оценки: Baseline]
• Adjustment disorder (both children 3-6 and 7-18years) [Срок оценки: Baseline and Follow-up two weeks later. In nonclinical samples, data will be only assessed at Baseline.]
• Regulation of Emotional Expression (Children and adolescents aged 7 to 18 years) [Срок оценки: Baseline]
• Potentially traumatic events (Children aged 3 to 6 years) [Срок оценки: Baseline and Follow-up two weeks later. In nonclinical samples, data will be only assessed at Baseline.]
• PTSD (Children aged 3 to 6 years) [Срок оценки: Baseline and Follow-up two weeks later. In nonclinical samples, data will be only assessed at Baseline.]
• Behavioral Problems (Children aged 3 to 6 years) [Срок оценки: Baseline]
• Quality of Life (Children aged 3 to 6 years) [Срок оценки: Baseline]