Pain and impairment beliefs in chronic low back pain: validation of the Pain and Impairment Relationship Scale (PAIRS).

Few validated instruments are available to assess beliefs and attitudes that patients have regarding pain, or ability to function despite discomfort. The Pain and Impairment Relationship Scale (PAIRS) was developed to tap these important beliefs and attitudes in chronic pain patients. Preliminary data indicate that the PAIRS is internally consistent and significantly related to impairment in a highly selected pain clinic sample of patients, including some chronic low back pain patients. The present study was designed to extend the validation of the PAIRS to a more general sample of chronic benign low back pain patients. Furthermore, additional tests supported the discriminant, convergent and divergent validity, as well as the reliability and relative independence from favorable self-report response bias of the PAIRS, by respectively demonstrating that: (1) the impairment beliefs assessed with the PAIRS were more prominent in chronic low back pain (CLBP) patients than in matched non-pain, healthy controls; (2) scores on the PAIRS were significantly related to measures of physical impairment, but not to physicians ratings of disease severity; (3) the impairment beliefs assessed with the PAIRS are readily distinguishable from cognitive distortions and emotional distress; (4) PAIRS scores for chronic low back pain patients are relatively consistent over time; and (5) PAIRS scores are not significantly associated with measures of favorable self-report response bias. We conclude that the PAIRS has demonstrated at least preliminary utility for applications by researchers and clinicians interested in chronic pain.