Background: Anxiety is a common comorbidity in patients with COPD, yet it remains underrecognized. Existing anxiety measures contain somatic items that can overlap with symptoms of COPD and side effects of medications. There is a need for a disease-specific nonsomatic anxiety scale to screen and measure anxiety in patients with COPD.
Methods: In phase 1, 88 patients with COPD (mean age 71 years, 36% men) completed a 16-item scale developed with patients and clinicians. Six items were removed using item and factor analysis. In phase 2, 56 patients with COPD (mean age 70 years, 48% men) completed the 10-item scale and other self-report measures of anxiety, quality of life, and functional limitations. Of these, 41 patients completed the scale on a second occasion, 14 days later. Construct validity (using confirmatory factor analysis [CFA]), discriminant validity, convergent validity, and anxiety screening accuracy were explored.
Results: The Anxiety Inventory for Respiratory Disease (AIR) had high internal consistency (Cronbach α = 0.92) and test-retest reliability (intraclass correlation coefficient = 0.81) and excellent convergent validity, correlating with the Hospital Anxiety and Depression-Anxiety subscale (r = 0.91, P < .001). The scale also discriminated between patients with clinical anxiety (measured using the Patient Health Questionnaire) and those without (U = 9, P < .001). A cutoff score of 14.5 yielded a sensitivity of 0.93 and specificity of 0.98 for detection of clinical anxiety. A two-factor model of general anxiety and panic symptoms had the best fit according to CFA.
Conclusions: The AIR is a short, user-friendly, reliable, and valid scale for measuring and screening anxiety in patients with COPD.