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

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

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

Setting: 15 U.S. primary care clinics.

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

Measurements: 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.

Results: 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.

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

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