The contribution of pain in determining the health status of cancer patients with bone metastases: A secondary analysis of data from three Phase III registration trials

Background: We aimed to provide a simple, descriptive health-status profile for cancer patients with bone metastases, based on the EuroQol EQ-5D, a tool commonly used to measure health utility scores, and to evaluate its association with the Brief Pain Inventory (BPI), a legacy pain-assessment tool. Although pain is one of five health-status dimensions measured by the EQ-5D, our understanding of how pain relates to the other EQ-5D dimensions is limited. Methods: We derived data from 5500 patients with bone metastases who completed the EQ-5D and BPI. Regression analyses examined how BPI severity and interference scores correlated with EQ-5D utility scores and how BPI items associated with EQ-5D items, for the entire sample and by disease-type subgroup. Results: Regardless of cancer site, the percentage of patients reporting moderate/severe problems in each of the five EQ-5D dimensions were pain/discomfort, 78%; usual activities, 58%; mobility, 55%; anxiety/depression, 57%; and self-care, 26%. BPI pain interference explained more of the variability in the EQ-5D utility scores than did pain severity (R²= 41% vs. 34%). BPI worst pain, average pain, pain now, interference with general activity, and interference with work significantly predicted EQ-5D pain/discomfort, with odds ratio estimates <1. Conclusions: Pain/discomfort was the worst-rated dimension of the EQ-5D in this population, but the relationship of this item to BPI pain severity was modest, suggesting that the single pain item of the EQ-5D may be of limited utility in studies for which pain is an endpoint. Significance: Health-status dimensions include more than pain. We examine the contribution of pain severity and pain-related functional interference in determining the health status of cancer patients with bone metastases. The pain dimension from a health-status measure may be an inadequate metric in clinical trials/clinical practice when pain is an important outcome.