Reliability and validity of the Arabic version of the EORTC QLQ-C30 and QLQ-BR23 questionnaires

Materials and methods: A cross-sectional study was carried out. A total of 337 subjects were recruited from the Oncology Centre in Bahrain and 239 consented to participation. 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 20. The reliability of the EORTC QLQ-C30 and QLQ-BR23 questionnaires was examined using Cronbach's alpha test. The construct validity of both questionnaires was tested using the exploratory factor analysis.

Results: Exploratory factor analysis results of EORTC QLQ-C30 showed that Kaiser-Meyer-Olkin (KMO) measure of sampling adequacy was 0.878 and Bartlett's Test of Sphericity is <0.001. The extracted four-factor model explained 51.52% of the total variance. Relating to EORTC-QLQ-BR23, the KMO value was 0.735 and Bartlett's Test of Sphericity showed a significance of p<0.001 and extracted a three-factor model which explained a total variance of 46.05%. The Cronbach's alpha coefficient results for EORTC QLQ-C30 and QLQ BR-23 were 0.927and 0.844 respectively which reflects high internal consistency.

Conclusion: The EORTC QLQ-C30 and QLQ-BR23 questionnaires are feasible and promising instruments to measure the levels of HRQOL among Arabic-speaking women with breast cancer in future studies with some suggested modifications in some of the domains or items