Questionnaire-Description

The QLQ-C30 is a 30-item questionnaire designed to assess the quality of life of cancer patients in various clinical settings. The questionnaire is divided into several scales and subscales that cover important aspects of patients’ lives:

Functioning Scales: Assess physical, emotional, cognitive, and social functioning, as well as the ability to perform roles (role functioning).

Symptom Scales: Cover common symptoms experienced by cancer patients, such as fatigue, pain, nausea, and vomiting.

Global Health Status/Quality of Life Scale: Provides an overall evaluation of perceived health and quality of life.

Additional Questions: Address other symptoms and issues affecting patients, such as sleep disturbances, loss of appetite, constipation, and the financial impact of the disease.

Responses are scored using a Likert scale, allowing patients to evaluate the severity of symptoms and their quality of life.

Data Analysis and Usage

Data collected from the QLQ-C30 are used to assess the quality of life of cancer patients, both in clinical trials and therapeutic interventions. Analyses include:

Descriptive statistics to describe patients’ conditions.

Statistical analysis to compare changes in quality of life during or after treatment.

Reliability analysis to ensure the internal consistency of the questionnaire’s scales.

Factor analysis to confirm the structural validity of the various dimensions of the scale.

These data are crucial for understanding how treatment affects patients and for developing improved therapeutic protocols.

Purpose

The goal of the EORTC QLQ-C30 is to provide a comprehensive and reliable assessment of the quality of life of cancer patients. The scale helps:

Assess the impact of the disease and treatments on patients’ daily lives.

Monitor changes in quality of life during the course of treatment.

Inform decision-making for individualized patient care.

Conduct clinical trials to evaluate the effectiveness of new treatments.

Calibration

The calibration of the QLQ-C30 includes the following stages:

Reliability analysis to measure the internal consistency of the scales using Cronbach’s alpha, ensuring the stability of responses.

Confirmatory factor analysis to validate the structure of the subscales.

Cross-cultural adaptation and cross-validation in different languages and cultural contexts, making the QLQ-C30 a globally accepted tool.

Bibliography

Aaronson, N. K., Ahmedzai, S., Bergman, B., Bullinger, M., Cull, A., Duez, N. J., … & Takeda, F. (1993). The European Organization for Research and Treatment of Cancer QLQ-C30: A quality-of-life instrument for use in international clinical trials in oncology. Journal of the National Cancer Institute, 85(5), 365-376.

Fayers, P. M., & Bottomley, A. (2002). Quality of life research within the EORTC—the EORTC QLQ-C30. European Journal of Cancer, 38, 125-133.

Scott, N. W., Fayers, P. M., Aaronson, N. K., Bottomley, A., de Graeff, A., Groenvold, M., … & Sprangers, M. A. (2008). EORTC QLQ-C30 reference values. Quality of Life Research, 17(8), 1147-1157.