Danish population-based reference data for the EORTC QLQ-C30: associations with gender, age and morbidity

Area of Science:

• Health outcomes research
• Quality of life assessment
• Epidemiology

Background:

• General population reference data are crucial for interpreting health-related quality of life (HRQoL) results.
• Existing European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire C30 (EORTC QLQ-C30) reference data are limited, with only seven countries represented.
• Danish reference data for the EORTC QLQ-C30 version 1 existed for women (collected in 1992), but not for version 3.0 for both genders.

Purpose of the Study:

• To generate Danish general population reference values for the EORTC QLQ-C30 version 3.0.
• To investigate associations between EORTC QLQ-C30 outcomes and age, gender, and morbidity.
• To examine trends in HRQoL over time in the Danish population.

Main Methods:

• An age- and gender-stratified random sample of 3,080 Danes was selected from the Danish Civil Registration System.
• The EORTC QLQ-C30 (version 3.0) was administered electronically and via mail.
• A questionnaire on socio-demographics and morbidity was included.

Main Results:

• A total of 1,832 individuals (60.1% response rate) participated.
• Response rates varied by age group (41.9% for 20-29 years to 76.1% for 70-79 years).
• Most EORTC QLQ-C30 subscales showed strong associations with age and morbidity.
• Small but statistically significant gender differences were observed in five of fifteen scales.
• Danish women showed a slight trend towards improved function and reduced symptoms compared to 20 years prior, significant in three subscales.

Conclusions:

• This study presents the first Danish general population reference values for the EORTC QLQ-C30 version 3.0.
• Age and morbidity are identified as critical confounders in HRQoL studies.
• These reference data are essential for accurate interpretation of EORTC QLQ-C30 results in Danish clinical and research settings.