The assessment of anxiety and fear in persons with chronic pain: a comparison of instruments.

Instruments used to study anxiety and fear responses related to chronic pain vary along two dimensions. They differ in terms of the stimuli or situations that evoke anxiety responses and the types of anxiety responses included (i.e. cognitive, motoric, and physiological). This study examined relations of variables from the Pain Anxiety Symptoms Scale (PASS), the Fear-Avoidance Beliefs Questionnaire (FABQ), the Fear of Pain Questionnaire (FPQ), and the trait version of the Spielberger State-Trait Anxiety Inventory (STAI) with variables related to pain severity, perceived disability, and pain behavior. Subjects were 45 consecutive referrals to a university pain clinic who completed these measures during their evaluation. Results suggested that anxiety responses directly related to the patient's particular pain sensations are more relevant to the understanding of chronic pain than are more general tendencies to respond anxiously or fear more varied pain stimuli. Regression analyses showed that empirically selected subsets of the anxiety variables predict from 16 to 54% of the variance in pain severity, disability and pain behavior. Also, assessment of multiple anxiety response types appears useful for understanding pain behavior and disability. Further study of fear and anxiety responses of persons with pain is likely to benefit from careful selection of measures dependent on the stimulus and response dimensions assessed.