Validation of the Generalized Anxiety Disorder-7 (GAD-7) and GAD-2 in patients with migraine

Subjects in this study were new patients with migraine who had consecutively visited a outpatients headache clinic in the Department of Neurology at Kyungpook National University Hospital from December 2014 to May 2015. Patients were adolescents and adults (aged 16–65 years old) who were newly diagnosed at our clinic or were already diagnosed but had not taken triptans, preventive medicines, or other neuropsychiatric agents within the last month. A diagnosis of migraine was based on the International Classification of Headache Disorders, 3^rd edition, beta version [18]. Patients were excluded if they were unable to cooperate in the psychiatric interview or had difficulty understanding the questionnaire because of illiteracy, mental retardation, serious medical, neurological, or psychiatric disorders, and alcohol or drug abuse. Patients with a probable migraine and those declining the interview were also excluded.

A cross-sectional study was conducted as part of a hospital-based study that examined the impact of psychiatric disorders on migraine and migraine-associated medications, such as triptans and preventive medicines. The Institutional Review Board of Kyungpook National University Hospital approved the study. All participants gave written informed consent. Subject’s medical charts were reviewed to collect demographic, social, and clinical information for a computerized database. Sociodemographic data included age, gender, education, employment, household income (earning at least three million KRW per month, equivalent to 2800 USD per month or not), and marital status (married or unmarried, divorced, and bereaved). Clinical data included the type of migraine, age at onset, disease duration, attack frequency, attack duration, family history, and accompanying symptoms (presence of photophobia, phonophobia, or osmophobia). A family history of migraine was defined as an existing diagnosis of migraine in a lineal ascendant and/or siblings. Photophobia, phonophobia, and osmophobia were defined as hypersensitivity to light, sound, and certain odors during migraine attacks that could cause avoidance of those stimulations or aggravation of migraine symptoms. Patients were asked whether they experienced symptoms during the preceding year.

To measure the reliability of the GAD-7 and GAD-2 in eligible subjects, one neuropsychologist examined their GAD using the Mini International Neuropsychiatric Interview-Plus Version 5.0.0 (MINI) [19]. Subsequently, patients provided several self-reported questionnaires, including the Beck Anxiety Inventory (BAI) [20], the Korean version of the Migraine Disability Assessment Scale (MIDAS) [21], the Headache Impact Test-6 (HIT-6) [22], and the Migraine-Specific Quality of Life (MSQoL) [23], to examine the validity of the GAD-7 and GAD-2.

The GAD-7 and GAD-2 were designed for use in primary care patients [15, 16]. The GAD-7 consists of a self-report questionnaire that allows for the rapid detection of GAD [15]. Subjects are asked if they were bothered by anxiety related problems over the past two weeks by answering seven items on a 4-point scale. The total scores ranged from 0 to 21. At a cutoff score of 9, the GAD-7 had a sensitivity of 89 % and a specificity of 82 % for detecting GAD compared with a structured psychiatric interview [15]. The GAD-2 is a short version of the tool that is composed of the first two questions of the GAD-7 [16]. At a cutoff score of 2, the GAD-2 had a sensitivity of 86 % and a specificity of 83 % for detecting GAD [16]. The GAD-7 was translated into the Korean language, and was freely downloadable on the Patient Health Questionnaire website (www.​phqscreeners.​com) [25]. The translated version was translated back into English by a Korean English teacher. Finally, the two versions were compared by a native English speaker who concluded that they were identical. Thereafter, we administered it to 20 Korean PWE for the evaluation of potential problems in comprehension or cultural differences. No further adaptations were required.

The BAI is a 21-item self-report measure of anxiety severity. The scale consists of 21 items, each describing a common symptom of anxiety. The respondent is asked to rate how much he or she has been bothered by each symptom over the past week on a 4-point scale from 0 to 3. The following cutoff points were used: 0–21, normal; 22–26, mild disturbance; 27–31, moderate disturbance; and 32–63, severe disturbance. The Korean version of the BAI has been validated [20]. Those who scored more than 21 points on the BAI were considered to have anxiety symptoms. Cronbach’s α was 0.9.

The Korean version of the MIDAS, a 5-item questionnaire that was designed to evaluate disability during the previous three months, was used in this study [21]. Patients were asked to report decreased performance in the domains of work/school, household work, and family/social activities. Scores (0–27) measure the overall level of disability: Grade I (0–5), Grade II (6–10), Grade III (11–20), and Grade IV (above 21). Cronbach’s α was 0.75.

The HIT-6 was developed in the United States to measure a wider spectrum of headache-induced burden [26]. Items in the HIT-6 cover several domains: pain, social functioning, role functioning, vitality, cognitive functioning, and psychological distress. Each item is answered on a 5-point Likert scale (6 = never, 8 = rarely, 10 = sometimes, 11 = very often, 13 = always). The total scores ranged from 36 to 78; larger scores indicate a greater impact. For interpretation, HIT-6 scores are categorized in four groups: scores ≤49 indicate little or no impact, scores between 50 and 55 indicate some impact, scores between 56 and 59 indicate a substantial impact, and scores ≥60 indicate a severe impact [27]. The Korean version of the HIT-6 was validated and Cronbach’s α was 0.85 [22].

The MSQoL developed by Wagner et al. and is a valid and reliable tool for clinical migraine research [28]. A Korean translation of this 25-item questionnaire has been validated [23]. The items are rated on a 4-point scale (1–4). The total scores ranged from 25 to 100. A lower total score indicates a poorer QOL. Cronbach’s α was 0.93.

The Statistical Package for the Social Sciences (SPSS version 21.0) was used for data analysis. The Med Calc 8.0 was used to perform receiver operating characteristic (ROC) analyses to measure sensitivity, specificity, positive predictive values (PPVs) and negative predictive values (NPVs) for a range of cutoff scores of the GAD-7 and GAD2 with respect to the diagnoses of GAD by the MINI-Plus 5.0.0. Optimal cutoff scores were also computed using criteria that minimize the Euclidean distance from point (sensitivity and specificity) to point in the x-y plane. The descriptive statistics are presented as counts, percentages, means, and standard deviations. Independent t-tests, Mann-Whitney U tests, and Chi-square tests were used to compare continuous or categorical variables. Cronbach’s α was computed to ascertain internal consistency and was recalculated after items were removed. Nonparametric correlations (Spearman’s ρ) were used to determine the validity of the GAD-7 and GAD-2. The level of statistical significance was set at p < 0.05.