Validation of the PHQ-9 in adults with dissociative seizures

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

doi:10.1016/j.jpsychores.2021.110487

Maria Baldellou Lopez, Laura H Goldstein + Show 6 more

Open Access

https://doi.org/10.1016/j.jpsychores.2021.110487

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Abstract

BackgroundThe PHQ-9 is a self-administered depression screening instrument. Little is known about its utility and accuracy in detecting depression in adults with dissociative seizures (DS). ObjectivesUsing the Mini – International Neuropsychiatric Interview as a reference, we evaluated the diagnostic accuracy of the PHQ-9 in adults with DS, and examined its convergent and discriminant validity and uniformity. MethodsOur sample comprised 368 people with DS who completed the pre-randomisation assessment of the CODES trial. The uniformity of the PHQ-9 was determined using factor analysis for categorical data. Optimal cut-offs were determined using the area under the curve (AUC), Youden Index, and diagnostic odds ratio (DOR). Convergent and discriminant validity were assessed against pre-randomisation measures. ResultsInternal consistency of the PHQ-9 was high (α = 0.87). While the diagnostic odds ratio suggested that a cut-off of ≥10 had the best predictive performance (DOR = 14.7), specificity at this cut off was only 0.49. AUC (0.74) and Youden Index (0.48) suggested a ≥ 13 cut-off would yield an optimal sensitivity (0.81) and specificity (0.67) balance. However, a cut-off score of ≥20 would be required to match specificity resulting from a cut-off of ≥13 in other medical conditions. We found good convergent and discriminant validity and one main factor for the PHQ-9. ConclusionsIn terms of internal consistency and structure, our findings were consistent with previous validation studies but indicated that a higher cut-off would be required to identify DS patients with depression with similar specificity achieved with PHQ-9 screening in different clinical and non-clinical populations.

Highlights

Dissociative seizures (DS) superficially resemble epileptic seizures but are not caused by the abnormal electrical discharges in the brain
Brief summary of diagnostic accuracy findings. This is the first study assessing the validity of the Patient Health Questionnaire-9 (PHQ-9) for depression-screening in adults with dissociative seizures (DS), comparing it to the M
While the PHQ-9 should never, in isolation, be used as a diagnostic tool for clinical depression, these findings suggest that it is a useful screening method for depressive symptoms allowing users to describe the likelihood of a diagnosis of clinical depression at particular cut-off scores

Summary

Introduction

Dissociative seizures (DS) superficially resemble epileptic seizures but are not caused by the abnormal electrical discharges in the brain. Prevalence rates of depression in adults with DS range from 21% to 60% and are higher than in the general population and patients with epilepsy [6]. A recent systematic review found that depression correlated more closely with HRQoL than with seizure-related factors, and lower depression scores were the only determinant of higher HRQoL [9], suggesting that successful treatment of depression may improve clinical outcomes in patients with DS [10]. Conclusions: In terms of internal consistency and structure, our findings were consistent with previous validation studies but indicated that a higher cut-off would be required to identify DS patients with depression with similar specificity achieved with PHQ-9 screening in different clinical and non-clinical populations

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