Validation of the Generalized Anxiety Disorder-7 in people with epilepsy: A MEPSY study
Introduction
Epidemiological studies have demonstrated that people with epilepsy (PWE) were more likely to develop depression and anxiety compared with those without epilepsy. In a Canadian population-based study, 24.4% of PWE had symptoms of a mood disorder, and its prevalence rate was 1.85 times higher than that of people without epilepsy [1]. Anxiety disorder was found in 14.1% of PWE, which was 1.26 times higher than that of people without epilepsy. Furthermore, the prevalence rate of coexisting mood and anxiety disorders in PWE was increased up to 34.2%. In a Korean hospital-based study, the frequency of depression in PWE was 27.8%, which was 3.16 times higher than that of the healthy controls, and the frequency of anxiety in PWE was 15.3%, which was 4.78 times higher than that of the healthy controls [2]. On the other hand, one study showed uncomplicated PWE carry only a modest risk of psychiatric comorbidity, which is generally mild and is not higher than the general population [3].
Depression and anxiety have been associated with poor seizure control, high rates of adverse events of antiepileptic drugs (AEDs), increased felt stigma and suicidal ideation, and, finally, impaired quality of life (QOL). In a Korean study, the rates of depression and anxiety in people with uncontrolled epilepsy were 3.88 and 4.78 times higher than those in people with well-controlled epilepsy, respectively [2]. Depression and anxiety appeared to increase adverse effects associated with AEDs in people visiting tertiary care centers [4], [5]. The frequency of felt stigma and suicidal ideation was significantly higher in patients with depression or anxiety than in those without these symptoms [2], [6]. Finally, according to the impact of depression and anxiety on these variables, PWE exhibiting depression or anxiety showed a meaningful impairment of QOL compared with those without these symptoms [2], [7]. Moreover, the impairment of QOL was maximal when PWE had a coexisting depression and anxiety [2]. Therefore, the early identification and management of depression and anxiety are indispensable for maintaining psychosocial functioning [8].
The Hospital Anxiety and Depression Scale (HADS) is a 14-item self-report screening scale that was originally developed to indicate the possible presence of anxiety and depression states in general medical settings [9]. It has been validated in several studies and used in community studies of psychological outcome in epilepsy [10], [11], [12], [13], [14]. In addition, one study investigated the prevalence of anxiety as defined by the HADS in PWE [15].
Although several screening instruments are useful to identify anxiety, there are no validated instruments for PWE. The Generalized Anxiety Disorder-7 (GAD-7) was recently developed in the USA as a valuable screening tool for detecting GAD in primary care patients [16]. It consists of a brief, 7-item questionnaire and takes less than 3 min to complete, and a score of > 9 is indicative of a GAD. It has been widely used by general practitioners [17]. It can not at this time be recommended to screen for GAD in PWE because it has a few items with somatic symptoms that can be confused with adverse effects of AEDs or cognitive symptoms of the seizure disorder or the underlying neurologic disorder associated with epilepsy [18]. Therefore, the aim of this study was to measure the value of GAD-7 as a screening tool in PWE.
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Subjects
We included subjects who consecutively visited epilepsy clinics of secondary and tertiary care hospitals. They were 18 years or older, had a current diagnosis of epilepsy, were taking one or more AEDs for at least 1 year, and had the ability to provide informed consent and to agree with the study protocol. Subjects who had insufficient information in their medical records, who had mental retardation or serious medical, neurological, or psychiatric disorders that prevented them from understanding
Results
A total of 300 patients visited our epilepsy clinics during the study period. Among them, 57 patients were excluded because of mental retardation (n = 34), presence of clinically significant medical or neurological disease (n = 13), and refusal to take part in the study (n = 10). Thereafter, 243 patients were invited to participate in the study. According to MINI-Plus 5.0.0 criteria, 51 (21.0%) patients were diagnosed as having GAD. Demographic and clinical characteristics and self-report
Discussion
To our knowledge, this is the first study to investigate the usefulness of the GAD-7 as a screening tool in PWE. The GAD-7 was easily comprehended and quickly completed by the patients. It was shown to have an excellent internal consistency reliability (Cronbach's α = 0.924), which was higher than that of the K-NDDI-E (Cronbach's α = 0.898) [22]. The GAD-7 has construct validity by a correlation with the K-NDDI-E score, the K-LAEP score, and the QOLIE-10 overall and subscale scores. The impact of
Funding
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
Acknowledgment
The authors thank Ju-Hui Lee, a neuropsychologist, for conducting the MINI-Plus 5.0.0 and for helping in the completion of self-report questionnaires and Won-Kee Lee, a professor of the Center of Biostatistics, School of Medicine, Kyungpook National University, for helping in the statistical analyses.
Disclosure
None of the authors has any conflict of interest to disclose.
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These authors contributed equally to the manuscript as first authors in this study.