Minimal Clinically Important Differences in the Cancer Quality of Life Questionnaires in Patients with Head and Neck Cancer.

Purpose: The purpose of this study is to determine the magnitude of change that is clinically meaningful in the EORTC QLQ-C30 and EORTC QLQ-HN35 instruments in head and neck cancer patients. Methods: Two hundred and twenty-two patients completed the EORTC QLQ-C30 and EORTC QLQ-HN35 at baseline and follow-up one to two months later. Minimal clinically important differences (MCIDs) were calculated through anchor- and distribution-based methods for improvement and deterioration. Karnofsky Performance status (KPS) was used as the anchor to determine meaningful change. Results: In the group of patients who deteriorated, more scales and symptoms demonstrated statistically significant meaningful change. EORTC QLQ-C30 meaningful change values for deterioration with KPS anchor ranged from 7.2 (physical functioning) to 16.7 units (Global Health Status), and for improvement ranged from 10.0 (role functioning) to 16.7 units (Global Health Status). Conclusions: We report-for the first time, to the best of our knowledge-MCID for EORTC QLQ-C30 and QLQ-HN35 in head and neck cancer patients. Knowledge of meaningful change in these questionnaires allows physicians to assess patient change over time, along with evaluating the impact of treatment on quality of life.