Anxiety, although as common as depression, has received less attention and is often undetected and undertreated.

To determine the current prevalence, impairment, and comorbidity of anxiety disorders in primary care and to evaluate a brief measure for detecting these disorders.

Criterion-standard study performed between November 2004 and June 2005.

15 U.S. primary care clinics.

965 randomly sampled patients from consecutive clinic patients who completed a self-report questionnaire and agreed to a follow-up telephone interview.

7-item anxiety measure (Generalized Anxiety Disorder [GAD]-7 scale) in the clinic, followed by a telephone-administered, structured psychiatric interview by a mental health professional who was blinded to the GAD-7 results. Functional status (Medical Outcomes Study Short Form-20), depressive and somatic symptoms, and self-reported disability days and physician visits were also assessed.

Of the 965 patients, 19.5% (95% CI, 17.0% to 22.1%) had at least 1 anxiety disorder, 8.6% (CI, 6.9% to 10.6%) had posttraumatic stress disorder, 7.6% (CI, 5.9% to 9.4%) had a generalized anxiety disorder, 6.8% (CI, 5.3% to 8.6%) had a panic disorder, and 6.2% (CI, 4.7% to 7.9%) had a social anxiety disorder. Each disorder was associated with substantial impairment that increased significantly (P�< 0.001) as the number of anxiety disorders increased. Many patients (41%) with an anxiety disorder reported no current treatment. Receiver-operating characteristic curve analysis showed that both the GAD-7 scale and its 2 core items (GAD-2) performed well (area under the curve, 0.80 to 0.91) as screening tools for all 4 anxiety disorders.

The study included a nonrandom sample of selected primary care practices.

Anxiety disorders are prevalent, disabling, and often untreated in primary care. A 2-item screening test may enhance detection.