Predictive validity of the pain and impairment relationship scale in a chronic nonmalignant pain population.
To examine the predictive and incremental validity of the Pain and Impairment Relationship Scale (PAIRS) and to determine its ability to measure changes in pain beliefs following interdisciplinary treatment. A before-after treatment design. A comprehensive interdisciplinary pain center at a large midwest university medical center. A cognitive-behavioral approach to pain management. The day-long program lasted 5 days a week for 4 weeks. Interventions were designed to improve physical functioning, reduce use of health care, and improve pain coping. Six-month follow-up outcome measures included interference with daily activity, pain severity, and life control as measured by the Multidimensional Pain Inventory, medication use measured by the Medication Quantification Scale, depression measured by the Beck Depression Inventory, and the number of health care visits and pain-related hospitalizations. Pretreatment PAIRS scores correlated significantly with interference with daily activities, pain severity, life control, health care visits, and depression. Stronger correlations were obtained between posttreatment PAIRS scores and all follow-up outcome measures. Posttreatment PAIRS scores accounted for a significant portion of the variance beyond that in demographic variables and pretreatment PAIRS scores in all but one of the follow-up measures. PAIRS scores changed significantly (p < .0001 ) in a positive direction after treatment. The PAIRS has excellent predictive validity, and can be used effectively to monitor individual and programmatic changes.