An assessment of reliability and validity of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire C30 among breast cancer patients in Qatar

Abstract

Introduction: Breast cancer has been the most common cancer type that affects women worldwide and subsequent treatment is oftenassociated with considerable psychological and quality of life (QoL). Aim: This study aimed to assess psychometric properties of theArabic version of the European Organization for Research and Treatment of Cancer (EORTC) general QoL questionnaire (QLQ?C30)for breast cancer patients in Qatar. Materials and Methods: This is a cross?sectional hospital?based study conducted on 678 breastcancer patients using Arabic version of the EORTC QLQ?C30 tool. Results: The mean age of women was 47.7 ± 10.2 years and33.4% of women had consanguineous parents. Six subscales out of the nine met the standards of reliability with coefficientsranging from 0.55 to 0.89. The mean score of all functioning scales was high >55. Advanced breast cancer stages of III–IV hadhigher symptomatic scores significantly than those in early stages for the physical function, cognitive, fatigue, insomnia, appetiteloss, constipation, and financial difficulties. Correlation coefficients between each item ranged from –0.113 to 0.960, and item21 (tense) and item 23 (irritable) had strongest negative correlations with their corresponding emotional functioning subscale,whereas items 29 (physical condition) and 30 (overall QoL) had the strongest positive correlation with Global Health/QoL subscale.Item 6 (limited work) showed a higher correlation with fatigue (r = 0.749). Likewise, item 19 (pain interfered with daily activities)of the pain subscale had higher correlations with physical functioning, role functioning, and fatigue subscales. Conclusion: QatariArabic version of the EORTC QLQ?C30 showed acceptable psychometric properties, which is a reliable and valid instrument, thatcan be used by oncologists.