Psychometric Properties of the General Anxiety Disorder 7-Item (GAD-7) Scale in a Heterogeneous Psychiatric Sample.

Sverre Urnes Johnson,Asle Hoffart,Pål Gunnar Ulvenes,Tuva Øktedalen

doi:10.3389/fpsyg.2019.01713

Sverre Urnes Johnson, Asle Hoffart + Show 2 more

Open Access

https://doi.org/10.3389/fpsyg.2019.01713

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Abstract

The GAD-7 is commonly used as a measure of general anxiety symptoms across various settings and populations. However, there has been disagreement regarding the factor structure of the GAD-7, and there is a need for larger studies investigating the psychometric properties of the measure. Patients undergoing treatment (N = 1201), both inpatient and outpatient patients, completed the GAD-7 at pre- and post-treatment. Measures of depression, well-being, and other anxiety measures were also completed, making it possible to investigate convergent and divergent validity. Internal consistency and convergent validity were excellent for the total sample, and there was acceptable variation related to treatment groups. We conducted an exploratory factor analysis (EFA) on a random sample (50%) of the patients at intake and then conducted a confirmatory factor analysis (CFA) to confirm the factor structure in the other part of the sample at intake. The EFA indicated a clear one-factor solution, but the one-factor solution with CFA provided a poor fit to the data. Correlating the residuals among items assessing somatic symptoms led to a good fit in a respecified CFA solution. The GAD-7 has excellent internal consistency, and the one-factor structure in a heterogeneous clinical population was supported.

Highlights

The 7-item Generalized Anxiety Disorders Scale (GAD-7; Spitzer et al, 2006) was developed as a screener for generalized anxiety disorder (GAD) in primary care settings.Originally, the development of the GAD-7 started with 13 items based on the criteria for GAD in the Diagnostic and Statistical Manual for Mental Disorders, Fourth Edition (DSM-IV) and other items in anxiety measures
Even though GAD-7 was developed for GAD, it is used in other anxiety disorders
The difference in effect was large using Hedges’ g = 1.00. These findings indicate that GAD-7 discriminates well between an anxious and a more general psychiatric population

Summary

Introduction

The 7-item Generalized Anxiety Disorders Scale (GAD-7; Spitzer et al, 2006) was developed as a screener for generalized anxiety disorder (GAD) in primary care settings. The development of the GAD-7 started with 13 items based on the criteria for GAD in the Diagnostic and Statistical Manual for Mental Disorders, Fourth Edition (DSM-IV) and other items in anxiety measures. Items were correlated with the total score. The seven items with the highest correlation with the total 13-item scale were selected (Spitzer et al, 2006). Even though GAD-7 was developed for GAD, it is used in other anxiety disorders. The GAD-7 is increasingly used as a measure for anxiety in general (Beard and Björgvinsson, 2014) and in anxiety disorder research (Dear et al, 2011)

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