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BRIEF RESEARCH REPORT article

Front. Psychiatry
Sec. Mood Disorders
Volume 15 - 2024 | doi: 10.3389/fpsyt.2024.1483782

Psychometric evaluation and community norms of the PHQ-9, based on a representative German sample

Provisionally accepted
Sören Kliem Sören Kliem 1*Cedric Sachser Cedric Sachser 2Anna Lohmann Anna Lohmann 1Dirk Baier Dirk Baier 3*Elmar Braehler Elmar Braehler 4Harald Gündel Harald Gündel 4Jörg Michael Fegert Jörg Michael Fegert 2
  • 1 Ernst-Abbe-Hochschule Jena, Jena, Germany
  • 2 Department of Child and Adolescent Psychiatry and Psychotherapy, Ulm University Medical Center, Ulm, Germany
  • 3 Zurich University of Applied Sciences, Winterthur, Zürich, Switzerland
  • 4 Department of Medical Psychology and Medical Sociology, University Hospital Leipzig, Leipzig, Lower Saxony, Germany

The final, formatted version of the article will be published soon.

    Background: The Patient Health Questionnaire (PHQ-9) is a popular tool for assessing depressive symptoms in both general and clinical populations. The present study used a large representative sample of the German adult population to confirm desired psychometric functioning and to provide updated population norms.Methods: The following psychometric properties were assessed: (i) Item characteristics (item means, standard deviations and inter-item correlations), (ii) Construct validity (correlations of the PHQ-9 sum-score with scores obtained from instruments assessing depression, anxiety and somatization (GAD-7, BSI-18), (iii) Internal consistency (coefficient omega), (iv) Factorial validity (via confirmatory factor analysis of the assumed one factorial model) as well as (v) Measurement invariance (via multi-group confirmatory factor analyses across gender, age, income and education).Results: The study found that the PHQ-9 had sound psychometric properties in terms of internal consistency and construct validity, and that measurements obtained with the tool could be compared across gender and age.Limitations: Despite using a representative sample, the response rate was only 42.6%. Furthermore, diagnostic efficiency cannot be assessed as there were no clinical interviews conducted.The updated population based norms, which are presented for the total sample 1 Kliem et al.as well as separated by gender and various age-groups, provide a useful reference for clinical practice and epidemiological research.

    Keywords: PHQ-9, major depression, Self-report questionnaire, Population norms, Psychometrics, Measurement invariance

    Received: 20 Aug 2024; Accepted: 01 Nov 2024.

    Copyright: © 2024 Kliem, Sachser, Lohmann, Baier, Braehler, Gündel and Fegert. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence:
    Sören Kliem, Ernst-Abbe-Hochschule Jena, Jena, Germany
    Dirk Baier, Zurich University of Applied Sciences, Winterthur, 8401, Zürich, Switzerland

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.