Adaptation and initial psychometric validation of the Latvian version of EORTC QLQ-C30 and QLQ-BR45 in women with breast cancer

Abstract

To culturally adapt and initially evaluate the psychometric properties of the Latvian versions of the EORTC QLQ-C30 and breast cancer-specific EORTC QLQ-BR45 in women with breast cancer. The study was conducted within a pilot project implementing the ICHOM Breast Cancer Standard Set in a specialised university hospital in Latvia. Translation and cultural adaptation followed the EORTC procedure and included expert review and cognitive debriefing. Psychometric evaluation used baseline data from 142 women and six-month follow-up data from 47. Analyses included item-level indicators, internal consistency, multitrait scaling, inter-scale correlations, correlations with the Stress Symptom Scale, and paired change analyses. Conditional QLQ-BR45 items were treated as structurally missing when not applicable. Expert review and cognitive debriefing supported linguistic, conceptual, and cultural appropriateness. Reliability and item-scale correspondence were acceptable for several domains, with particularly strong multitrait scaling results for QLQ-BR45 Body Image, Sexual Functioning, and Breast Symptoms. Correlations between EORTC functioning and symptom domains and the Stress Symptom Scale were generally in the hypothesised directions. Six-month findings showed clinically plausible changes in functioning and treatment-related symptoms, but estimates were based on a smaller follow-up sample and reduced valid samples for some conditional scales. The Latvian EORTC QLQ-C30 and QLQ-BR45 showed acceptable preliminary psychometric performance. The findings provide initial support for their use to assess HRQoL and breast cancer-specific symptoms in Latvia, while larger multicentre and longitudinal studies are needed to evaluate additional measurement properties and responsiveness. This study evaluated Latvian versions of two questionnaires used internationally to understand quality of life and symptoms in women with breast cancer: the EORTC QLQ-C30 and QLQ-BR45. Latvia lacked a comprehensive evaluation of these versions in women receiving breast cancer care. The translations were reviewed by specialists and tested with patients to ensure that the wording was understandable and culturally appropriate. We then analysed questionnaire data from 142 women before treatment and from 47 women six months later. Several questionnaire scales showed acceptable reliability and the expected relationships with related symptoms. The follow-up results also showed plausible changes during treatment, although the smaller follow-up group means these findings are preliminary. Overall, the Latvian questionnaires appear suitable for cautious use in research and clinical practice, but larger studies are needed to confirm how well they perform across different patient and treatment groups.