Self-report differentiation of anxiety and depression in chronic pain.

The psychometric distinctiveness of self-reported anxiety and depression in patients with chronic pain was investigated. The item-level responses of 220 patients with heterogeneous pain conditions from the Beck Depression Inventory and State--Trait Anxiety Inventory State--Anxiety scale were submitted to common factor analysis. Three first-order factors were identified: depression, anxiety-absent, and anxiety-present. One second-order factor of negative affect was also identified. Correlations of first-order factor scores with other psychometric measures suggested only minor distinctiveness. The findings indicated that it is possible to distinguish anxiety and depression psychometrically in patients with chronic pain but suggested that negative affect may be the primary underlying construct of the affective experience of these patients.