Validity of the Greek EORTC QLQ‐C30 and QLQ‐BR23 for measuring health‐related quality of life in breast cancer patients

KONTODIMOPOULOS N., NTINOULIS K. & NIAKAS D. (2011) European Journal of Cancer Care 20 , 354–361
Validity of the Greek EORTC QLQ‐C30 and QLQ‐BR23 for measuring health‐related quality of life in breast cancer patients The aim of this study was to assess construct validity and internal consistency reliability of the Greek EORTC QLQ‐C30 and QLQ‐BR23 instruments. A sample of female breast cancer patients (n= 105) were self‐administered the QLQ‐C30, QLQ‐BR23 and SF‐36 and questions on treatment and socio‐demographic status. Hypothesised scale structure, reliability (Cronbach's α) and construct validity (convergent, discriminative, concurrent and known‐groups) were assessed. Multitrait scaling confirmed scale structure of the QLQ‐C30 and QLQ‐BR23 with good item convergence (92% and 85%), and discrimination (87% and 84%) rates. Cronbach's α was >0.70 for all but one scale (cognitive functioning). Strength of Spearman's correlations between the QLQ‐C30 and SF‐36 scales assessing similar health‐related quality of life dimensions ranged from 0.25 to 0.64 (P < 0.01). Construct validity was confirmed with satisfactory results for interscale correlations and known‐groups comparisons. QLQ‐BR23 scales showed comparatively low (<0.40) correlations with QLQ‐C30 functional scales, and higher correlations with conceptually related symptom scales. Most QLQ‐C30 and QLQ‐BR23 scales discriminated between pre‐treatment and current treatment patients. The overall psychometric results for the Greek version of the QLQ‐C30 and QLQ‐BR23 confirmed it as a reliable and valid questionnaire for assessing breast cancer‐specific HRQoL in Greece.