Validation of EORTC QLQ-C30 and QLQ-BR23 questionnaires in the measurement of quality of life of breast cancer patients in Singapore

Objective: To validate EORTC QLQ-C30 and EORTC QLQ-BR23 questionnaires and to measure the health-related quality of life (HRQOL) of women with breast cancer in Singapore during their first 4 years of post-diagnosis and treatments. Methods: A quantitative and cross-descriptive sectional study. All of 170 subjects were recruited in a Singapore tertiary cancer center. The European Organization for Research and Treatment-QOL questionnaire and breast cancer specific module (EORTC QLQ-C30 and QLQ-BR23) were used to measure the HRQOL among women with breast cancer. All statistical tests were performed using SPSS Version 18. The reliability of the EORTC QLQ-C30 and QLQ-BR23 questionnaires was examined using Cronbach's alpha test. EORTC QLQ-C30 was validated against EuroQol Group's 5-domain questionnaires (EQ5D) by examining its concurrent validity using Pearson Product Moment Correlation to calculate the total scores. Results: The Cronbach's alpha coefficient results for EORTC QLQ-C30 and QLQ BR-23 were 0.846 and 0.873 respectively which suggested relatively good internal consistency. The correlation between EORTC QLQ-C30 and EQ5D QOL instruments demonstrated a modest linear relationship (r=0.597; P