Psychometric analysis of the Generalized Anxiety Disorder scale (GAD-7) in primary care using modern item response theory
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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.
In: PLOS ONE, Vol. 12, No. 8, 2017, p. e0182162.Research output: SCORING: Contribution to journal › SCORING: Journal article › Research › peer-review
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TY - JOUR
T1 - Psychometric analysis of the Generalized Anxiety Disorder scale (GAD-7) in primary care using modern item response theory
AU - Jordan, Pascal
AU - Shedden-Mora, Meike C
AU - Löwe, Bernd
PY - 2017
Y1 - 2017
N2 - 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.
AB - 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.
KW - Journal Article
U2 - 10.1371/journal.pone.0182162
DO - 10.1371/journal.pone.0182162
M3 - SCORING: Journal article
C2 - 28771530
VL - 12
SP - e0182162
JO - PLOS ONE
JF - PLOS ONE
SN - 1932-6203
IS - 8
ER -