The measurement of pain from metastatic bone disease: capturing the patient's experience

Pain is prevalent for large numbers of patients with metastatic cancer, and this pain is often due to bone metastases. Despite the availability of effective pain treatments and various pain management guidelines, multiple studies document the undertreatment of pain in patients with cancer. The most frequently identified barriers to appropriate pain management are physician underestimation of the patient's pain, inadequate pain assessment, and patient reluctance to report pain. A first step toward reducing inadequate pain control in clinical practice is adequate assessment of cancer pain using validated pain measurement instruments. Using treatment for bone pain as an example, we discuss how patient satisfaction measures and self-report measures of pain and other symptoms, symptom interference with patient function, and related adverse effects can be combined with appropriate trial design to provide the information needed to choose the best possible treatment for bone pain. Symptom assessment needs to be done via standardized questionnaires, administered at appropriate times during the trial. The Brief Pain Inventory uses 11-point numerical rating scales to measure both pain severity and the resulting functional interference caused by pain. These severity and interference ratings can be further categorized as mild, moderate, or severe, as required to implement most pain management guidelines and define outcome expectations for clinical trials. Consistent pain measurement and standardized recording of analgesic use across clinical trials would enhance comparability and increase the chances that treatment decisions for management of bone pain could be evidence based. These and other considerations in the design of clinical trials are discussed.