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

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.