Research report
Validity of the GAD-7 scale as an outcome measure of disability in patients with generalized anxiety disorders in primary care

https://doi.org/10.1016/j.jad.2010.07.010Get rights and content

Abstract

Objective

To explore the validity of the GAD-7 scale as an outcome measure of disability in primary care.

Methods

A random sample of 212 subjects was recruited in primary care clinics; 50% diagnosed with generalized anxiety disorder (GAD) by DSM-IV criteria and 50% concurrent matched controls. The GAD-7, the Hamilton Anxiety Scale (HAM-A), and the abridged 12-item version of World Health Organization Disability Scale (WHO-DAS-II) were administered. The number of visits to primary care and specialty clinics was also recorded.

Results

Strong and significant (p < 0.001) correlations were found between GAD-7 and HAM-A (r = 0.852) and WHO-DAS-II (r = 0.704) scores, particularly for Participation in Society (r = 0.741), Understanding and Communication (r = 0.679), and Life Activities (0.638) dimensions. Moderate but significant correlations were also found between GAD-7 score and the number of visits to Primary Care (r = 0.393) and Specialty clinics (r = 0.373). In all cases, an overall relation was observed between GAD-7 severity levels and disability scores [F (3,208) = 25.4, p < 0.001] as assessed by the WHO-DAS II, with higher mean disability values related to higher severity levels.

Conclusions

The GAD-7 scale has been shown to highly correlate not only with specific anxiety but also with disability measures. It has been shown that more severe GAD levels correlate with higher disability states and tend to demand more health care attention. As the GAD-7 is self-administered and is not time consuming, this instrument could be a good choice to explore the level of patient disability in subjects with GAD in primary care settings.

Introduction

Anxiety is the manifestation of an emotion where the individual feels and describes him/herself as restless, nervous, tense, afraid, or excessively worried about specific and/or undefined issues (Andrews et al., 2010, Behar et al., 2009). Generalized anxiety disorder (GAD) is often accompanied by physical symptoms such as fatigue, tremors, muscle tension, headaches, irritability, excessive perspiration, etc. (Wittchen et al., 1994, NIMH, 2005). While the exact cause of GAD cannot be specified, there are population groups at greater risk of suffering it (Mahe and Valgo, 2000, Ansseau et al., 2004). As with other anxiety disorders, both psychiatric and somatic comorbidity is high in GAD (Cano Vindel, 2005, Simon, 2009, Romera et al., 2010). The effects of GAD on the health-related quality of life and functionality are even greater than those observed in major depression (Bereza et al., 2009), and these impairments cannot be totally accounted for by concomitant diseases (Judd et al., 1998, Stein, 2001). Anxiety disorders are the most common mental disorders, with a 1-year prevalence of 12% in the adult population, a 12-month prevalence of 2%–3%, and a lifetime prevalence of 5% (Ansseau et al., 2004, The ESEMeD/MHEDEA 2000 investigators, 2004). GAD lifetime prevalence was estimated on 2.8% in Europe (Kessler et al., 2005). In a clinical setting, GAD prevalence has been estimated at 7.3% in primary care and up to 13% in psychiatric outpatient clinics (Caballero et al., 2009, Chocrón Bentata et al., 1995). On the other hand, the impact of GAD on the patient's daily life (loss of well-being, utilization of healthcare resources, etc.), and particularly on functionality, is assumed to be considerable (Bereza et al., 2009, Alonso et al., 2004, Andlin-Sobocki and Wittchen, 2005, Wittchen, 2002).

Not surprisingly, the scientific community has been interested in developing specific, psychometrically sound measurement tools able to identify and quantify the severity of GAD and to assess the efficacy of psychosocial and psychopharmacological interventions like the Worry and Anxiety Questionnaire (WAQ) (Dugas et al., 2001) and the GAD-Q-IV (Newman et al., 2002) in such patients. The GAD-7 scale, a recent, simple 7-item tool based on DSM-IV criteria, that is easy to administer and without undue burden on the patient or the clinician, has been developed to identify probable cases of GAD and has shown strong properties for screening likely GAD cases (Spitzer et al., 2006, Swinson, 2006). Also, it has been shown to distinguish between patients with different degrees of anxiety and different levels of healthcare resource utilization (medical visits) (Spitzer et al., 2006, Swinson, 2006). On the other hand, one of the most comprehensive measures of disability and patient functionality is the World Health Organization Disability Assessment Schedule II (WHO-DAS II), which is a multidimensional instrument developed by the World Health Organization (WHO, 2000). This instrument captures six domains of functionality: understanding and communicating, getting around, self care, getting along with people, life activities, and participation in society, reflecting two dimensions of disability: activity limitations and participation. It is compatible with an international classification system, the World Health Organization International Classification of Functioning, Disability and Health (WHO, 2000) and treats all disorders at parity when establishing the level of functioning. A shorter, 12-item version of the instrument has also been developed, which is recommended for epidemiological studies and routine outcome assessment (World Health Organization, 2000, Vázquez-Barquero et al., 2000).

There has been some recent, relevant discussion on whether normal and pathological worries should be considered qualitatively distinct processes (typological approach) or if they lie on a single continuum (dimensional approach) (Ruscio et al., 2001, Fraley and Waller, 1998, Meehl, 1992, Ruscio, 2002, Ayuso-Mateos et al., 2010). The GAD-7 scale has been developed and used as a screening tool, but it might be the case that it also could be used to rate patients based on the severity of their worry symptoms and help identify individuals who would benefit from specific clinical interventions aimed at reducing worry (Flett et al., 1997). The goal of this study was to explore the validity of the GAD-7 scale as an outcome measure of disability in primary care using the abridged 12-item version of the WHO-DAS II Scale in patients with generalized anxiety disorder as a reference instrument. Also, we tested the concordance of the GAD-7 scale with the Hamilton Anxiety Scale (Hamilton, 1969) when identifying different severity levels of anxiety. This study is particularly of interest for the scientific community evaluating the functionality of GAD, as no previous research has explored whether a single measure can be used as a first step. This is especially salient for the busy, complex primary care setting, in which simplifying initial recognition of mental disorders may in fact make wider efforts at recognition more feasible.

Section snippets

Study design

The present study was designed as a multicenter, observational, cross-sectional study carried out under routine clinical practice conditions in primary care clinics, in subjects with GAD according to DSM-IV criteria. All subjects in the study, both patients and controls, had to give their informed consent in order to be enrolled in the study and have their data analyzed. The study protocol was approved by the Research Ethics Committee of the Universidad Autónoma de Madrid and by the Research

Patient characteristics and treatments

A total of 14 researchers from primary care clinics participated in the study and recruited a sample of 212 subjects between June 2008 and January 2009. The mean patient age was 47.59 years (sd = 15.8) and 72.6% were women. Table 1 summarizes the main socio-demographic and clinical data by the study group. No statistical differences were found in the socio-demographic characteristics, but clinical variables were significantly different between study groups (p < 0.001). In the GAD group, 79% of

Discussion

To our knowledge, this is the first study that has examined the relationship of the 12-item WHO-DAS II and the GAD-7 scales in patients with GAD in primary care settings focusing on disability only. One of the main strengths of our research is that the recruited cohort included geographically, culturally, and economically diverse patients, and a sex and age matched control group. Results obtained in the present study demonstrate that GAD carries with it a marked worsening of an individual's

Role of the funding source

Data collection and analysis were supported by a grant from Pfizer España. All investigators had complete access to the data, participated in the analysis and interpretation of results, and drafted the manuscript. Two authors are employed by the funding company. All of the authors agreed to submit the article for publication. The study received non-financial sponsorship from the Spanish Society of Rural and General Medicine (SEMERGEN).

Conflict of interest

Javier Rejas and Olga Freire are full-time employees of Pfizer, the entity providing financial support for the study. The rest of authors declare no competing interest.

Acknowledgments

The authors thank the participating family physicians for their collection of data and the members of the Research Committee of the Spanish Society of Rural and General Medicine for their advice on the design of the study.

References (45)

  • M. Von Korff et al.

    Self-report disability in an international primary care study of psychological illness

    J. Clin. Epidemiol.

    (1996)
  • J. Alonso et al.

    Disability and quality of life impact of mental disorders in Europe: results from the European Study of the Epidemiology of Mental Disorders (ESEMeD) project

    Acta Psychiatr. Scand.

    (2004)
  • P. Andlin-Sobocki et al.

    Cost of affective disorders in Europe

    Eur. J. Neurol.

    (2005)
  • G. Andrews et al.

    Generalized worry disorder: a review of DSM-IV generalized anxiety disorder and options for DSM-V

    Depress. Anxiety

    (2010)
  • Ayuso-Mateos, J.L., Nuevo, R., Verdes, E., Naidoo, N., Chatterji, S., 2010. From depressive symptoms to depressive...
  • L. Caballero et al.

    Clinical prevalence and reason for visit of patients with generalized anxiety disorder seen in the psychiatry out-patient clinics in Spain. Results of the LIGANDO study

    Actas Esp. Psiquiatr.

    (2009)
  • P.J. Candilis et al.

    The hidden costs of untreated anxiety disorders

    Harv. Rev. Psychiatry

    (1997)
  • A. Cano Vindel

    Trastornos de ansiedad, Sociedad Española para el estudio de la Ansiedad y el Estrés (SEAS)

    (2005)
  • L. Chocrón Bentata et al.

    Prevalencia de Psicopatología en un centro de atención primaria

    Aten. Prim.

    (1995)
  • M.J. Dugas et al.

    Le questionnaire sur l'inquiétude et l'anxiété: validation dans des échantillons non cliniques et cliniques

    J. Thér. Comport. Cogn.

    (2001)
  • G.L. Flett et al.

    The continuity of depression in clinical and nonclinical samples

    Psychol. Bull.

    (1997)
  • R.C. Fraley et al.

    Adult attachment patterns: a test of typological model

  • Cited by (0)

    View full text