Otto B. Walter

The Perceived Stress Questionnaire (PSQ) reconsidered: validation and reference values from different clinical and healthy adult samples.

Objective: The aim was to translate, revise, and standardize the Perceived Stress Questionnaire (PSQ) by Levenstein et al. (1993) in German. The instrument assesses subjectively experienced stress independent of a specific and objective occasion. Methods: Exploratory factor analyses and a revision of the scale content were carried out on a sample of 650 subjects (Psychosomatic Medicine patients, women after delivery, women after miscarriage, and students). Confirmatory analyses and examination of structural stability across subgroups were carried out on a second sample of 1,808 subjects (psychosomatic, tinnitus, inflammatory bowel disease patients, pregnant women, healthy adults) using linear structural equation modeling and multisample analyses. External validation included immunological measures in women who had suffered a miscarriage. Results: Four factors (worries, tension, joy, demands) emerged, with 5 items each, as compared with the 30 items of the original PSQ. The factor structure was confirmed on the second sample. Multisample analyses yielded a fair structural stability across groups. Reliability values were satisfactory. Findings suggest that three scales represent internal stress reactions, whereas the scale “demands” relates to perceived external stressors. Significant and meaningful differences between groups indicate differential validity. A higher degree of certain immunological imbalances after miscarriage (presumably linked to pregnancy loss) was found in those women who had a higher stress score. Sensitivity to change was demonstrated in two different treatment samples. Conclusion: We propose the revised PSQ as a valid and economic tool for stress research. The overall score permits comparison with results from earlier studies using the original instrument. PSQ = Perceived Stress Questionnaire; ICD = International Classification of Diseases; QoL = quality of life; IBD = inflammatory bowel disease; SEM = structural equation modeling; MSA = multisample analysis; TLI = Tucker-Lewis index; CFI = comparative fit index.

Evaluation of a computer-adaptive test for the assessment of depression (D-CAT) in clinical application.

In the past, a German Computerized Adaptive Test, based on Item Response Theory (IRT), was developed for purposes of assessing the construct depression [Computer‐adaptive test for depression (D‐CAT)]. This study aims at testing the feasibility and validity of the real computer‐adaptive application.

An evaluation of patient-reported outcomes found computerized adaptive testing was efficient in assessing stress perception

OBJECTIVES This study aimed to develop and evaluate a first computerized adaptive test (CAT) for the measurement of stress perception (Stress-CAT), in terms of the two dimensions: exposure to stress and stress reaction. STUDY DESIGN AND SETTING Item response theory modeling was performed using a two-parameter model (Generalized Partial Credit Model). The evaluation of the Stress-CAT comprised a simulation study and real clinical application. A total of 1,092 psychosomatic patients (N1) were studied. Two hundred simulees (N2) were generated for a simulated response data set. Then the Stress-CAT was given to n=116 inpatients, (N3) together with established stress questionnaires as validity criteria. RESULTS The final banks included n=38 stress exposure items and n=31 stress reaction items. In the first simulation study, CAT scores could be estimated with a high measurement precision (SE<0.32; rho>0.90) using 7.0+/-2.3 (M+/-SD) stress reaction items and 11.6+/-1.7 stress exposure items. The second simulation study reanalyzed real patients data (N1) and showed an average use of items of 5.6+/-2.1 for the dimension stress reaction and 10.0+/-4.9 for the dimension stress exposure. Convergent validity showed significantly high correlations. CONCLUSIONS The Stress-CAT is short and precise, potentially lowering the response burden of patients in clinical decision making.

Functioning and validity of a Computerized Adaptive Test to measure anxiety (A-CAT).

Background: The aim of this study was to evaluate the Computerized Adaptive Test to measure anxiety (A‐CAT), a patient‐reported outcome questionnaire that uses computerized adaptive testing to measure anxiety. Methods: The A‐CAT builds on an item bank of 50 items that has been built using conventional item analyses and item response theory analyses. The A‐CAT was administered on Personal Digital Assistants to n=357 patients diagnosed and treated at the department of Psychosomatic Medicine and Psychotherapy, Charité Berlin, Germany. For validation purposes, two subgroups of patients (n=110 and 125) answered the A‐CAT along with established anxiety and depression questionnaires. Results: The A‐CAT was fast to complete (on average in 2 min, 38 s) and a precise item response theory based CAT score (reliability>.9) could be estimated after 4–41 items. On average, the CAT displayed 6 items (SD=4.2). Convergent validity of the A‐CAT was supported by correlations to existing tools (Hospital Anxiety and Depression Scale‐A, Beck Anxiety Inventory, Berliner Stimmungs‐Fragebogen A/D, and State Trait Anxiety Inventory: r=.56–.66); discriminant validity between diagnostic groups was higher for the A‐CAT than for other anxiety measures. Conclusions: The German A‐CAT is an efficient, reliable, and valid tool for assessing anxiety in patients suffering from anxiety disorders and other conditions with significant potential for initial assessment and long‐term treatment monitoring. Future research directions are to explore content balancing of the item selection algorithm of the CAT, to norm the tool to a healthy sample, and to develop practical cutoff scores. Depression and Anxiety, 2008.

Entwicklungsschritte für einen computeradaptiven Test zur Erfassung von Angst (A-CAT1)

Zusammenfassung. Die empirische Erfassung psychischer Merkmale erfolgt in der Regel mit Instrumenten, die auf der Grundlage der klassischen Testtheorie entwickelt wurden. Seit den 60er Jahren bietet sich hierzu mit der Item Response Theory (IRT) eine Alternative an, die verschiedene Vorteile verspricht. Auf ihrer Grundlage konnen u.a. computeradaptive Tests (CATs) entwickelt werden, welche die Auswahl der vorgelegten Items dem Antwortverhalten der Patienten anpassen und damit eine hohere Messgenauigkeit bei reduzierter Itemzahl ermoglichen sollen. Wir haben verschiedene Schritte zur Entwicklung eines CAT zur Erfassung von Angst unternommen, um zu prufen, ob sich die theoretischen Vorzuge der IRT auch in der praktischen Umsetzung bestatigen lassen. In dem vorliegenden Beitrag wird die Entwicklung der zu Grunde liegenden Itembank dargestellt. Hierfur wurde auf Daten von N = 2348 Patienten zuruckgegriffen, die an der Medizinischen Klinik mit Schwerpunkt Psychosomatik der Charite zwischen 1995 und 2001 im Rah...

Implementation of the Kids-CAT in clinical settings: a newly developed computer-adaptive test to facilitate the assessment of patient-reported outcomes of children and adolescents in clinical practice in Germany.

PurposeTo describe the implementation process of a computer-adaptive test (CAT) for measuring health-related quality of life (HRQoL) of children and adolescents in two pediatric clinics in Germany. The study focuses on the feasibility and user experience with the Kids-CAT, particularly the patients’ experience with the tool and the pediatricians’ experience with the Kids-CAT Report.MethodsThe Kids-CAT was completed by 312 children and adolescents with asthma, diabetes or rheumatoid arthritis. The test was applied during four clinical visits over a 1-year period. A feedback report with the test results was made available to the pediatricians. To assess both feasibility and acceptability, a multimethod research design was used. To assess the patients’ experience with the tool, the children and adolescents completed a questionnaire. To assess the clinicians’ experience, two focus groups were conducted with eight pediatricians.ResultsThe children and adolescents indicated that the Kids-CAT was easy to complete. All pediatricians reported that the Kids-CAT was straightforward and easy to understand and integrate into clinical practice; they also expressed that routine implementation of the tool would be desirable and that the report was a valuable source of information, facilitating the assessment of self-reported HRQoL of their patients.ConclusionsThe Kids-CAT was considered an efficient and valuable tool for assessing HRQoL in children and adolescents. The Kids-CAT Report promises to be a useful adjunct to standard clinical care with the potential to improve patient–physician communication, enabling pediatricians to evaluate and monitor their young patients’ self-reported HRQoL.

Transitioning from Fixed-Length Questionnaires to Computer-Adaptive Versions

To investigate how an existing questionnaire can be transformed into a computer-adaptive version, we developed an adaptive version of the Interpersonal Competence Questionnaire (ICQ). This adaptive version was based on a representative sample (N = 1934) of respondents who answered 30 items from a German translation of the ICQ. A random half of the sample was used to evaluate test dimensionality, calibrate the items, and model the relation between person parameters and raw total scores. The other random half of the sample was employed to assess the comparability of person parameters and raw scores. After these tests and item calibration, 28 items remained in the item pool. A high correlation was found between raw scores and estimated scores using all items. Raw scores could be predicted accurately from estimated person parameters. These results indicate that our approach is an effective technique for transforming an existing questionnaire into a computer-adaptive version.