Objectives: To examine the performance of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30) global health status/quality of life (QoL) scale and two summary scores to detect changes in the QoL profile over time, according to changes in the individual scales.
Study design and setting: Data came from 167 clinical trial patients with unresectable (advanced) hepatocellular carcinoma. The global health status/QoL scale of the questionnaire contained two items: overall health and overall QoL. Nordin and Hinz proposed summary scores for the questionnaire. A mixed-effect model was fitted to estimate trends in scores over time.
Results: Predominantly the individual scale scores declined over time; however, the global health status/QoL score was stable [rate of change = -0.3 per month; 95% confidence interval (CI): -1.2, 0.6]. Nordin's summary score, which gave equal weight to the 15 questionnaire scales, and Hinz's summary score, which gave equal weight to the 30 questionnaire items, showed a statistically significant decline over time, 3.4 (95% CI: -4.5, -2.4) and 4.2 (95% CI: -5.3, -3.0) points per month, respectively.
Conclusion: In contrast to the global health status/QoL scale, the summary scores proposed by Nordin and Hinz detected changes in subjects' QoL profile described by the EORTC QLQ-C30 individual scales.
Keywords: Advanced hepatocellular carcinoma; Cancer; EORTC QLQ-C30; Quality of life; Response shift; Scoring procedure.
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