Level of Concordance Between Proxy and Cancer Patient Ratings in Brief PainInventory

The objective of this study was to assess whether caregivers serve as valid and reliable proxies for the assessment of a patient's pain level using the Brief Pain Inventory (BPI) assessment tool.

Twenty-seven patients with cancer with pain, referred for health care management to the Toronto Sunnybrook Regional Cancer Centre and the Sunnybrook and Women's College Health Sciences Centre, and their proxies participated in this study. Patient and proxy completed the BPI independently, with proxies given explicit instructions to rate and answer the questions from the perspective of the patient. Patient and proxy also completed a data extraction form to obtain patient/proxy characteristics such as sex, age, primary cancer site, and relationship. An intraclass correlation coefficient (ICC) was performed for each question of the BPI.

In this study, we found poor to good agreement for questions that are subjective (eg, average pain), whereas the highest agreement was for worst pain scoring (ICC = 0.72). Poor to moderate agreement was found for questions that are objective (eg, walking ability), suggesting that the functional interference questions of the BPI may be too vague for proxies to respond reliably.

The findings indicate that proxies and patients agree well on worst pain levels but agree much less on the effectiveness of pain medications and patients' average level of pain. Further investigations should examine other tools for pain assessment that may be more reliably used by a proxy.