Introduction: Quality of life (QOL) is an important treatment endpoint in advanced cancer patients with brain metastases. In clinical trials, statistically significant changes can be reached in a large enough population; however, these changes may not be clinically relevant.
Objective: The objective of this study was to determine the minimal clinically important difference (MCID) for the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire brain module (EORTC QLQ-BN20) in patients with brain metastases.
Methods: Patients undergoing radiotherapy for brain metastases completed the EORTC QLQ-BN20 and QLQ-C30/C15-PAL at baseline and 1-month follow-up. MCIDs were calculated for both improvement and deterioration using anchor- and distribution-based approaches. The anchor of overall QOL (as assessed by question 30 or question 15 on the QLQ-C30 and QLQ-C15-PAL, respectively) was used to determine meaningful change.
Results: A total of 99 patients were included. The average age was 61 years, and the most common primary cancer sites were the lung and breast. Statistically significant meaningful differences were seen on two scales. A decrease of 6.1 (95 % confidence interval (CI) 0.8 to 11.4) units and 13.8 (0.2 to 27.4) units was required to represent clinically relevant deterioration of seizures and weakness of legs, respectively. Distribution-based MCID estimates tended to be closer to 0.5 SD on the EORTC QLQ-BN20.
Conclusion: Understanding MCIDs allows physicians to determine the impact of treatment on patients' QOL and allows for determination of sample sizes for clinical trials. Future studies should be conducted to validate our findings in a larger population of patients with brain metastases.