Anxiety disorders are the most prevalent mental health disorders and are associated with substantial disability and reduced well-being. It is unknown whether the relative impact of different anxiety disorders is due to the anxiety disorder itself or to the co-occurrence with other anxiety disorders. This study compared the functional impact of combinations of anxiety disorders in primary care out-patients.

A total of 1004 patients with panic disorder (PD), generalized anxiety disorder (GAD), social anxiety disorder (SAD) or post-traumatic stress disorder (PTSD) provided data on their mental and physical functioning, and disability. Multivariate regressions compared functional levels for patients with different numbers and combinations of disorders.

Of the patients, 42% had one anxiety disorder only, 38% two, 16% three and 3% all four. There were few relative differences in functioning among patients with only one anxiety disorder, although those with SAD were most restricted in their work, social and home activities and those with GAD were the least impaired. Functioning levels tended to deteriorate as co-morbidity increased.

Of the four anxiety disorders examined, GAD appears to be the least disabling, although they all have more in common than in distinction when it comes to functional impairment. A focus on unique effects of specific anxiety disorders is inadequate, as it fails to address the more pervasive impairment associated with multiple anxiety disorders, which is the modal presentation in primary care.