I read a paper which provided mean scores for the functional and symptom scales. What are these values scored out of? (i.e., what is considered optimal /maximal?) Is a lower score a worse quality of life?

The EORTC QLQ-C30 comprises 30 items (i.e. single questions), 24 of which are aggregated into nine multi-item scales, that is, five functioning scales (physical, role, cognitive, emotional and social), three symptom scales (fatigue, pain and nausea/vomiting) and one global health status scale. The remaining six single-item (dyspnoea, appetite loss, sleep disturbance, constipation, diarrhoea and the financial impact) scales assess symptoms. No item occurs in more than one scale.

Scoring of the QLQ-C30 is performed according to QLQ-C30 Scoring manual, which is available to download via our website on the manuals page. All of the scales and single-item measures range in score from 0 to 100. Higher score for the functioning scales and global health status denotes a better level of functioning (i.e. a better state of the patient), while higher scores on the symptom and single-item scales indicate a higher level of symptoms (i.e. a worse state of the patient).

Note: Some authors may reverse the symptom scores to follow the functioning scales interpretation (and vice versa). The reason for this is usually for consistency in signs of the change scores across the various scales. Care should be taken when interpreting the change scores in such scenarios.