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


Type
Article
Change log
Authors
Gorbunova, Anastasia 
Haghish, Fardzadeh E 
Real, Ruben 
Zeldovich, Marina 
Abstract

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.

Description
Keywords
Depression, Anxiety, Validity, Comorbidity, Bifactorial Model
Journal Title
Journal of clinical medicine
Conference Name
Journal ISSN
2077-0383
Volume Title
9
Publisher
Sponsorship
Seventh Framework Programme (EC grant 602150)
ZNS - Hannelore Kohl Stiftung (Germany)