THE INTERPRETATION OF SCORES FROM THE EORTC QUALITY-OF-LIFE QUESTIONNAIRE QLQ-C30

While quality of life (QOL) assessment is becoming more Common, interp reting the results remains problematic. This paper demonstrates an app roach to developing clinically-based interpretations for QOL outcomes, using the QLQ-C30 as an example. The results from 14 published QLQ-C3 0 studies which group patients by performance status, weight loss, tox icity, extent or severity of disease are collated. Groups with tower c linical status generally have worse QOL. The largest differences are b etween performance status groups, and the smallest differences are bet ween groups of patients with local disease and those with metastases. The physical and role scores have the largest ranges of means across p atient groups, and show the largest differences between clinical group s, while the cognitive and emotional scores have the smallest ranges o f means and differences. Sicker groups have larger score standard devi ations than healthier groups. Relatively large and small means and dif ferences, and corresponding effect sizes, are presented. Collectively, the results provide a sense of the relative sizes of means and of dif ferences, and of the types of clinical groups which give rise to them, thereby providing clinically-based benchmarks by which to interpret Q LQ-C30 results.