Elsevier

Psychiatry Research

Volume 256, October 2017, Pages 312-317
Psychiatry Research

Screening for generalized anxiety disorder in Spanish primary care centers with the GAD-7

https://doi.org/10.1016/j.psychres.2017.06.023Get rights and content

Highlights

  • Generalized anxiety disorder is highly prevalent in Spanish primary care centers.

  • The criterion validity was tested of a computerized version of the Spanish GAD-7.

  • The GAD-7 performed very well as a screening instrument with a cut-off of 10.

  • A ROC curve study was compared to the CIDI clinical interview as a gold standard.

Abstract

The aim of the study was to determine the criterion validity of a computerized version of the General Anxiety Disorder-7 (GAD-7) questionnaire to detect general anxiety disorder in Spanish primary care centers. A total of 178 patients completed the GAD-7 and were administered the Composite International Diagnostic Interview (CIDI) for DSM-IV Axis I Disorders, which was used as a reference standard. Sensitivity, specificity, positive and negative predictive values, and positive and negative likelihood ratios were calculated. A cut-off of 10 yielded a sensitivity of .87, a specificity of .78, a positive predictive value of .93, a negative predictive value of .64, a positive likelihood ratio of 3.96 a negative likelihood ratio of .17 and Younden's Index of .65. The GAD-7 performed very well with a cut-off value of 10, the most frequently used cut-off point. Thus, a computerized version of the GAD-7 is an excellent screening tool for detecting general anxiety disorder in Spanish primary care settings.

Introduction

Anxiety is the single most common mental disorder in Europe, affecting near 61.5 million people (Wittchen et al., 2011). However, reported prevalence rates for this disorder can vary substantially across countries. According to the European Study of the Epidemiology of Mental Disorders (ESEMeD), which assessed 21425 non-institutionalized adults in six different European countries, the lifetime prevalence of any anxiety disorder is 13.6% and the annual prevalence is 4.2% (Alonso et al., 2004). In Spain, by contrast, Haro et al. (2006) assessed a general population sample of 5473 adults, finding that the lifetime prevalence for any anxiety disorder was 9.4%, with a one-year prevalence of 5.7%. These figures are lower than those reported in the United States (US), where lifetime and annual prevalence rates for these disorders have been reported to be 29% and 11%, respectively (n = 9282) (Kessler et al., 2005). However, King et al. (2008) found no differences in the prevalence of anxiety disorders in the United Kingdom (UK) and Spain, the two countries with the highest prevalence rates in Europe. Despite the differences in prevalence rates among countries, there is little doubt that anxiety disorders are highly prevalent in Europe and more needs to be done to improve both detection and treatment.

In Spain, as in many countries, individuals with mental disorders are often first identified in primary care (PC) centers. A study involving 7936 PC patients in Spain found that 53.6% of the sample presented one or more mental disorders, with nearly 30% of the patients in that study presenting comorbidities and 11.5% suffering from concurrent affective, anxiety and somatoform disorders (Roca et al., 2009). Although anxiety disorders were only the third most common in that study (after affective and somatoform disorders), these still accounted for 25.6% of all mental disorders. The most common types of anxiety disorders were as follows: generalized anxiety disorder (GAD; 11.7%), panic disorder (PD; 9.7%), social phobia (.4%), and post-traumatic stress disorder (.3%). Another study (Serrano-Blanco et al., 2010) recruited 3815 patients from 77 different PC centers in Spain, finding a lifetime prevalence of 20.8% and an annual prevalence of 18.5% for any anxiety disorder. These prevalence rates are largely in line with those reported in other European countries (Alonso et al., 2004, Ansseau et al., 2004; Kroenke et al., 2007; Wittchen et al., 2002), and as Kessler (2007) observed, any differences are more likely to be due to methodological issues rather than cultural differences.

Of all the various types of anxiety disorders, GAD is the most common in PC settings (Wittchen, 2002). According to García-Campayo et al. (2012a), GAD is highly comorbid with other psychological disorders in PC patients in Spain (n = 2232), as follows: social anxiety (37%), depression (19.1%), phobia (14%), PD (10.7%), and obsessive-compulsive disorder (8%). Physical comorbidities are also common, including chronic pain (83.9%), gastrointestinal disorders (34%), cardiovascular diseases (17.3%), and diabetes (14%). As these findings show, GAD can have a large impact on the patient's physical status and, consequently, on other aspects of life. In addition, in that study, patients with GAD reported poor quality sleep and high sleep-onset latency, with only 16.2% of participants reporting restful sleep. Moreover, GAD can negatively impact quality of life and may lead to disability (Alonso et al., 2004, Rapaport et al., 2005), high absenteeism rates from work, and an increase in the use of health services. As a result, GAD is associated with enormous treatment-related expenses and costs associated with loss of productivity (Rovira et al., 2012). Like other common mental disorders in PC patients, anxiety disorders have become more common in Spain due to the ongoing economic crisis (Gili et al., 2013). Additionally, in many cases, the diagnosis of GAD in PC is incorrect or non-existent, with misdiagnosis rates as high as 71% (Fernández et al., 2010). For this reason, valid tools are needed to efficiently detect this disorder.

The 7-item GAD scale (GAD-7) is one of the tests used in the PC setting to detect the presence of GAD. The GAD-7 is the anxiety module of the Patient Health Questionnaire (PHQ), a screening test for mental disorders in PC (Spitzer et al., 1999) that is used to detect and measure GAD as well as other anxiety disorders. The original PHQ developed by Spitzer et al. (1999) had a moderate sensitivity of .63 and a good specificity of .97 for any anxiety disorder (using a cut-off score of 8 points). The Spanish version of the PHQ includes the GAD-7 with a 3-point scale as in the original version (Diez-Quevedo et al., 2001), and the operating characteristics of the Spanish version also had a moderate sensitivity (.69) and good specificity (.99).

In a later study (Spitzer et al., 2006), the authors developed a version of the GAD-7 that used a 4-point scale, reporting that a cut-off score of 10 or more was the best indicator for anxiety disorders (sensitivity, .89; specificity, .82). García-Campayo et al. (2010) subsequently developed and validated the Spanish version of the GAD-7, which—unlike the PHQ version developed by Diez-Quevedo et al. (2001)—used a 4-point response scale, similar to the original English-language version of Spitzer et al. (2006). This validated version was found to possess excellent psychometric properties (sensitivity, .87; specificity, .93)—similar to the original version—using a cut-off score of 10 for diagnosis. Feasibility and reliability were also excellent and the scale was shown to be one-dimensional through factor analysis, with an explained variance of 72%. Moreover, this version of the scale has been validated to measure disability in Spanish PC patients with GAD (Ruiz et al., 2011).

However, the predictive value of this scale has not yet been compared to a gold standard such as a clinical interview performed by a mental health professional. Indeed, using a computerized version of the GAD-7 in PC centers may be also useful. Given this context, the main aim of the present study was to study the criterion validity of a computerized version of the Spanish GAD-7 in a sample of PC patients in Spain who had been previously identified by a primary care physician (PCP) as suffering from anxiety or other emotional disorders.

Section snippets

Method

We studied the screening test characteristics (criterion validity) of a computerized version of the Spanish GAD-7 to detect GAD in users of PC services. These findings were then compared to the results with the Composite International Diagnostic Interview (CIDI), a diagnostic interview developed by the World Health Organization (WHO, 1990), which was used as the reference standard.

PHQ results

As Table 2 shows, of the 260 patients that completed the PHQ, a large proportion (n = 203; 78%) were diagnosed with major depressive disorder (MDD) according to PHQ-9 criteria (scores ≥ 10) and the DSM-IV diagnostic algorithm (n = 178; 68%). Approximately half of all patients (n = 141; 54%) were diagnosed with somatization disorder (SD) (PHQ-15 ≥ 5) and more than two-thirds (n = 180; 69%) were diagnosed with GAD (GAD-7 ≥ 10). In addition, comorbidity among disorders was high (n = 150; 58%),

Discussion

The results reported here support the value of a computerized version of the validated Spanish version of the GAD-7 as a screening tool for GAD among patients at Spanish PC centers. The screening test characteristics were consistent with those described previously by Spitzer et al. (2006) and García-Campayo et al. (2010). Unlike the validation of the Spanish version of the GAD-7, our results are supported by a clinical interview as a gold standard, which is the major strength of our study.

In

Acknowledgments

We thank all the PsicAP Research Group who kindly participated in this large project. This work was supported by Ministerio de Economía y Competitividad; Psicofundación, Foundation for the Scientific and Professional Development of Psychology in Spain and Fundación Mutua Madrileña. We also thank Bradley Londres for his assistance in editing and improving the manuscript.

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