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Psychometric analysis of the Generalized Anxiety Disorder scale (GAD-7) in primary care using modern item response theory

OBJECTIVE: The Generalized Anxiety Disorder scale (GAD-7) is one of the most frequently used diagnostic self-report scales for screening, diagnosis and severity assessment of anxiety disorder. Its psychometric properties from the view of the Item Response Theory paradigm have rarely been investigate...

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Autores principales: Jordan, Pascal, Shedden-Mora, Meike C., Löwe, Bernd
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5542568/
https://www.ncbi.nlm.nih.gov/pubmed/28771530
http://dx.doi.org/10.1371/journal.pone.0182162
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author Jordan, Pascal
Shedden-Mora, Meike C.
Löwe, Bernd
author_facet Jordan, Pascal
Shedden-Mora, Meike C.
Löwe, Bernd
author_sort Jordan, Pascal
collection PubMed
description OBJECTIVE: The Generalized Anxiety Disorder scale (GAD-7) is one of the most frequently used diagnostic self-report scales for screening, diagnosis and severity assessment of anxiety disorder. Its psychometric properties from the view of the Item Response Theory paradigm have rarely been investigated. We aimed to close this gap by analyzing the GAD-7 within a large sample of primary care patients with respect to its psychometric properties and its implications for scoring using Item Response Theory. METHODS: Robust, nonparametric statistics were used to check unidimensionality of the GAD-7. A graded response model was fitted using a Bayesian approach. The model fit was evaluated using posterior predictive p-values, item information functions were derived and optimal predictions of anxiety were calculated. RESULTS: The sample included N = 3404 primary care patients (60% female; mean age, 52,2; standard deviation 19.2) The analysis indicated no deviations of the GAD-7 scale from unidimensionality and a decent fit of a graded response model. The commonly suggested ultra-brief measure consisting of the first two items, the GAD-2, was supported by item information analysis. The first four items discriminated better than the last three items with respect to latent anxiety. CONCLUSION: The information provided by the first four items should be weighted more heavily. Moreover, estimates corresponding to low to moderate levels of anxiety show greater variability. The psychometric validity of the GAD-2 was supported by our analysis.
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spelling pubmed-55425682017-08-12 Psychometric analysis of the Generalized Anxiety Disorder scale (GAD-7) in primary care using modern item response theory Jordan, Pascal Shedden-Mora, Meike C. Löwe, Bernd PLoS One Research Article OBJECTIVE: The Generalized Anxiety Disorder scale (GAD-7) is one of the most frequently used diagnostic self-report scales for screening, diagnosis and severity assessment of anxiety disorder. Its psychometric properties from the view of the Item Response Theory paradigm have rarely been investigated. We aimed to close this gap by analyzing the GAD-7 within a large sample of primary care patients with respect to its psychometric properties and its implications for scoring using Item Response Theory. METHODS: Robust, nonparametric statistics were used to check unidimensionality of the GAD-7. A graded response model was fitted using a Bayesian approach. The model fit was evaluated using posterior predictive p-values, item information functions were derived and optimal predictions of anxiety were calculated. RESULTS: The sample included N = 3404 primary care patients (60% female; mean age, 52,2; standard deviation 19.2) The analysis indicated no deviations of the GAD-7 scale from unidimensionality and a decent fit of a graded response model. The commonly suggested ultra-brief measure consisting of the first two items, the GAD-2, was supported by item information analysis. The first four items discriminated better than the last three items with respect to latent anxiety. CONCLUSION: The information provided by the first four items should be weighted more heavily. Moreover, estimates corresponding to low to moderate levels of anxiety show greater variability. The psychometric validity of the GAD-2 was supported by our analysis. Public Library of Science 2017-08-03 /pmc/articles/PMC5542568/ /pubmed/28771530 http://dx.doi.org/10.1371/journal.pone.0182162 Text en © 2017 Jordan et al http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Jordan, Pascal
Shedden-Mora, Meike C.
Löwe, Bernd
Psychometric analysis of the Generalized Anxiety Disorder scale (GAD-7) in primary care using modern item response theory
title Psychometric analysis of the Generalized Anxiety Disorder scale (GAD-7) in primary care using modern item response theory
title_full Psychometric analysis of the Generalized Anxiety Disorder scale (GAD-7) in primary care using modern item response theory
title_fullStr Psychometric analysis of the Generalized Anxiety Disorder scale (GAD-7) in primary care using modern item response theory
title_full_unstemmed Psychometric analysis of the Generalized Anxiety Disorder scale (GAD-7) in primary care using modern item response theory
title_short Psychometric analysis of the Generalized Anxiety Disorder scale (GAD-7) in primary care using modern item response theory
title_sort psychometric analysis of the generalized anxiety disorder scale (gad-7) in primary care using modern item response theory
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5542568/
https://www.ncbi.nlm.nih.gov/pubmed/28771530
http://dx.doi.org/10.1371/journal.pone.0182162
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