Clinical significance of health status assessment measures in head and neck cancer: what do quality-of-life scores mean?

OBJECTIVES: To determine the magnitude of clinically significant differences in domain scores for a quality-of-life questionnaire specific to head and neck cancer; and to demonstrate a clinically relevant method of presenting head and neck cancer-specific quality-of-life data using cutoff scores and clinical anchors.
DESIGN: Anchor-based and distribution-based techniques for determining clinically significant differences in health-related quality-of-life scores were used.
SETTING: University-based tertiary care hospital. PATIENTS: A total of 421 patients with head and neck cancer enrolled in a longitudinal outcomes project. MAIN OUTCOME MEASURES: The Head and Neck Cancer Inventory; clinical anchor health status in the domains of speech, eating, and social disruption; and distribution-based clinically significant score differences.
RESULTS: Clinical anchor health states representing incremental levels of dysfunction were significantly correlated with domain scores for eating, speech, and social disruption. The anchor-based clinically important difference magnitudes were consistent with the values obtained using distribution-based techniques. For mean domain scores (minimum, 0; maximum, 100), differences of approximately 4, 10, and 14 or greater represented small, intermediate, and large clinically significant differences, respectively. Stratifying mean domain scores into low (0-30), intermediate (31-69), and high (70-100) categories allowed presentation of the health-related quality-of-life data in a clinically relevant format.
CONCLUSIONS: This study provides benchmarks for small, intermediate, and large clinically significant changes in scores and demonstrates the presentation of health-related quality-of-life data in a clinically useful format.