Exploratory factor analysis of the Pain Anxiety Symptoms Scale in patients with chronic pain complaints

The Pain Anxiety Symptoms Scale (PASS) is a 40-item self-report measure that consists of four subscales measuring aspects of pain-related anxiety and avoidance. Despite its growing popularity, there have been few studies of its psychometric properties. The primary purpose of this study was to determine the factor structure of the PASS in a sample of 259 chronic pain patients. Principal component analysis with oblique (Oblimin) rotation provided partial support for the factorial validity of the PASS. Five factors were extracted: (1) catastrophic thoughts, (2) physiological anxiety symptoms, (3) escape/avoidance behaviours, (4) cognitive interference, and (5) coping strategies. The use of analgesic medication did not influence the factor solution. The factors were characterised by correlating them with pain-related measures, and with measures of mood state. Implications are considered for revising the PASS subscales to provide a more comprehensive and factorially valid assessment of pain-related fear and avoidance.