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Open AccessArticle

Factorial Structure and Validity of Depression (PHQ-9) and Anxiety (GAD-7) Scales after Traumatic Brain Injury

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The Department of Social Psychology, Helmut Schmidt University, 22043 Hamburg, Germany
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The Institute of Medical Psychology and Medical Sociology, Georg August University, 37073 Göttingen, Germany
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Department of Public Health, Erasmus University Medical Center, 3000 Rotterdam, The Netherlands
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Institute of Medical Statistics, Medical Center, Georg August University, 37073 Göttingen, Germany
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Division of Anaesthesia, University of Cambridge/Addenbrooke’s Hospital, Box 157, Cambridge CB2 0QQ, UK
*
Author to whom correspondence should be addressed.
For the list of CENTER-TBI Investigators and Participants, see the Supplementary Material.
J. Clin. Med. 2020, 9(3), 873; https://doi.org/10.3390/jcm9030873
Received: 11 February 2020 / Revised: 10 March 2020 / Accepted: 11 March 2020 / Published: 23 March 2020
(This article belongs to the Section Psychiatry)
Background: The dimensionality of depression and anxiety instruments have recently been a source of controversy. Objectives and Design: In a European-wide sample of patients after Traumatic Brain Injury (TBI), we aim to examine the factorial structure, validity, and association of the Patient Health Questionnaire for depression (PHQ-9) and the Generalized Anxiety Disorder (GAD-7) instruments. This study is based on longitudinal observational data. We conducted analyses of factorial structure and discriminant validity of outcomes six-months after TBI. We also examined the prevalence, co-occurrence, and changes of scores on the PHQ-9 and GAD-7 at 3-, 6-, and 12-month post-TBI assessments. Participants: At six-months post-TBI assessment, 2137 (738 (34.5%) women) participants completed the PHQ-9 and GAD-7 questionnaires. For the longitudinal analysis, we had 1922 participants (672 (35.0%) women). Results: The results of exploratory factor analysis suggested a general latent construct underlying both PHQ-9 and GAD-7 measures. Confirmatory factor analyses showed a slight improvement in the fit indices for the bifactorial model. The Omega hierarchical test clearly differentiated two subfactors of PHQ-9 and GAD-7 items over and above the underlying general factor; however, most of the variance (85.0%) was explained by the general factor and the explained variance of the subfactors was small. The PHQ-9 and GAD-7 performed similarly in detecting post-traumatic stress disorder (PTSD). As defined by conventional cut-offs, depression and anxiety have different prevalence rates in the sample. The scales also differed in their relationships with the short form of health survey (SF-36v2) subscales. The longitudinal analysis showed high stability of depression and anxiety symptoms: 49–67% of the post-TBI patients with comorbid depression and anxiety reported the persistence of the symptoms over time. Discussion: The factorial structure analysis favors a general latent construct underlying both depression and anxiety scales among patients after TBI. We discuss the implications our findings and future research directions. View Full-Text
Keywords: depression; anxiety; bifactorial model; validity; comorbidity depression; anxiety; bifactorial model; validity; comorbidity
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Teymoori, A.; Gorbunova, A.; Haghish, F.E.; Real, R.; Zeldovich, M.; Wu, Y.-J.; Polinder, S.; Asendorf, T.; Menon, D.; CENTER-TBI Investigators and Participants; v. Steinbüchel, N. Factorial Structure and Validity of Depression (PHQ-9) and Anxiety (GAD-7) Scales after Traumatic Brain Injury. J. Clin. Med. 2020, 9, 873.

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