EORTC QOL Reference values and norm data

Definition

Reference values and norm data are used to compare PRO scores to a reference population.

• reference values: data are obtained from cancer patients, e.g. with a similar diagnosis, disease status, or treatment
• norm data: data are obtained from general population, e.g. of a specific country, region or age group.

Example

Application

• clinical practice and research
• individual and group-based data
• single and multiple assessment time points

Use in clinical practice:

• Reference values and norm data provide insight into typical score ranges and can support individualized treatment decisions.
• Reference values help determine whether a patient’s score is higher or lower than expected compared with a reference population. They are particularly meaningful for patients undergoing treatment or those in advanced stages of disease
• Norm data may be particularly useful for the analysis of PRO data from cancer survivors, i.e., when the quality of life is expected to mostly return to general population levels.

Limitations

• careful selection of reference population
• data on reference population must be available
• careful interpretation of deviations from expected scores

Available reference values/norm data

• EORTC QLQ-C30 normative data
• EORTC CAT Core normative data

Comparisons to a patient population (reference values) 

• EORTC QLQ-C30 reference values

Consider that it is important to select a comparable reference population (e.g. similar age group and sex) for a meaningful comparison of the scores of your patient. If in doubt, it is advisable to consult PRO experts.