Health Utility of Pain Response Versus Nonresponse to Palliative Radiation Therapy for Symptomatic Bone Metastases: Analyses Based on Real-World Data from 26 Centers.

Background: Utility values of responders and nonresponders are essential inputs in cost-effectiveness studies of radiation therapy for painful bone metastases but, to our knowledge, they have not been reported separately. Objective: We sought to determine the utility values of responders and nonresponders using data from a prospective observational study on bone metastases. Methods: The original prospective observational study was conducted at 26 centers in Japan. Of 232 enrolled patients, 181 whose pain scores at baseline were ≥2 were analyzed. Health-related quality of life (QOL) was measured using the EuroQol 5-dimensions 5-levels (EQ-5D-5L) instrument at baseline and 2- and 6-month follow-up assessments. At follow-up assessments, patients were categorized as responders or nonresponders. Pain response was assessed using the International Consensus Pain Response Endpoints. Results: Of the 181 patients analyzed, 133 (73%) and 84 (46%) were evaluable at the 2- and 6-month follow-up assessment, respectively. The EQ-5D-5L index score (utility) increased from baseline to the 2- and 6-month follow-up assessments; regarding opioid analgesic use, no clear trend was observed during the same period. The mean utility was significantly higher in responders than in nonresponders at both follow-up times. The mean daily oral morphine equivalent dose was significantly lower in responders than in nonresponders at both follow-up times. Conclusion: We determined utility values for responders and nonresponders. Pain response was associated with better QOL and less opioid use. Our utility values according to response status can be used for model input in future cost-effectiveness studies on radiation therapy for bone metastases.