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Performance of the GAD-7 in adults with dissociative seizures

Research output: Contribution to journalArticlepeer-review

Laura Goldstein, Silia Vitoratou, Jon Stone, Trudie Chalder, Maria Baldellou Lopez, Alan Carson, Markus Reuber

Original languageEnglish
Pages (from-to)15-21
Number of pages7
Accepted/In press22 Nov 2022
PublishedJan 2023

Bibliographical note

Funding Information: This paper describes independent research funded by the National Institute for Health and Care Research (Health Technology Assessment programme, 12/26/01, COgnitive behavioural therapy v. standardised medical care for adults with Dissociative non-Epileptic Seizures: A multicentre randomised controlled trial (CODES)). This study also represents independent research part-funded (LHG, SV and TC) by the National Institute for Health and Care Research (NIHR) Maudsley Biomedical Research Centre at the South London and Maudsley NHS Foundation Trust and King's College London. JS is supported by an NHS Scotland NHS Research Scotland (NRS) Career Fellowship and JS and AC also acknowledge the financial support of NRS through the Edinburgh Clinical Research Facility. MR benefitted from the support of the NIHR Sheffield Biomedical Research Centre (Translational Neuroscience). The views expressed in this publication are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care. Publisher Copyright: © 2022

King's Authors


Purpose: Little is known about the accuracy of the GAD-7, a self-report anxiety measure, in detecting generalised anxiety disorder (GAD) in people with dissociative seizures (DS). We evaluated the reliability, validity and uniformity of the GAD-7 using a diagnosis of GAD on the Mini-International Neuropsychiatric Interview as a reference. Methods: We assessed 368 adults with DS at the pre-randomisation phase of the CODES trial. Factor analysis for categorical data assessed GAD-7 uniformity. Diagnostic accuracy was assessed by estimating the area under the curve (AUC). We evaluated discriminant validity, reviewed data on convergent validity and calculated internal consistency. We explored correlations between GAD-7 scores and monthly DS frequency, frequency of severe seizures and measures of behavioural and emotional avoidance. Results: Internal consistency of the GAD-7 was high (α = 0.92). Factor analysis elicited one main factor and general measurement invariance. Diagnostic accuracy was fair (AUC = 0.72) but the best balance of sensitivity and specificity occurred at a cut-off of ≥12 and still had a specificity rate of only 68%. Discriminant and convergent validity were good. GAD-7 scores correlated positively with DS frequency, severe seizure frequency, behavioural and emotional avoidance (all p < 0.001). Conclusion: Findings regarding internal consistency and factor structure parallel previous psychometric evaluations of the GAD-7. Correlations between GAD-7 scores and DS occurrence/severity and avoidance are evidence of the concept validity of GAD-7 and provide further support for a fear-avoidance treatment model for DS. However, the utility of the GAD-7 as a diagnostic instrument for generalised anxiety disorder is limited in patients with DS.

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