Psychometric evaluation of the EORTC computerized adaptive test (CAT) fatigue item pool

Area of Science:

• Oncology
• Psychometrics
• Health Outcomes Research

Background:

• Fatigue is a prevalent symptom in cancer patients, significantly impacting their quality of life.
• Existing fatigue measures may lack the precision and flexibility needed for comprehensive assessment.
• The European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Group aims to enhance patient-reported outcomes.

Purpose of the Study:

• To develop a computerized adaptive test (CAT) for measuring cancer-related fatigue.
• To create a more precise and flexible fatigue assessment tool.
• To establish a CAT version compatible with the EORTC QLQ-C30 questionnaire.

Main Methods:

• Developed 41 new fatigue items based on literature and expert/patient input.
• Assessed psychometric properties including dimensionality, Item Response Theory (IRT) model fit, and Differential Item Functioning (DIF).
• Evaluated items in an international sample of 1,321 cancer patients.

Main Results:

• Factor analysis supported a unidimensional model for 37 items.
• Two items were removed due to poor IRT model fit.
• One item was excluded due to DIF across cancer types, resulting in a 34-item bank.

Conclusions:

• A 34-item fatigue item bank was successfully developed for CAT implementation.
• The new measure offers enhanced precision and flexibility in assessing cancer-related fatigue.
• The developed scale maintains backward compatibility with the EORTC QLQ-C30 fatigue scale.