Validation of the Lymphedema Quality of Life Inventory (LyQLI) in Greek Breast Cancer Patients: An Anatomical and Physiological Approach to Patient-Reported Prognosis

Introduction Lymphedema has been shown to have a substantial impact on patients' quality of life. A variety of questionnaires have been used in the literature to assess quality of life among breast cancer patients with lymphedema. Aim The aim of this study was to validate the Greek version of the Lymphedema Quality of Life Inventory (LyQLI), and to assess its reliability and validity among patients with lymphedema in Greece. Materials and methods A total of 93 patients with upper-limb lymphedema following breast cancer treatment were recruited from the General Hospital of Athens, "G. Gennimatas," Athens, Greece. The LyQLI questionnaire was translated into Greek and subsequently back-translated into English, following standard procedures for cross-cultural adaptation of patient-reported outcome measures. Content, face, and construct validity were evaluated, with the RAND version of the Short Form-36 (SF-36) serving as a comparative instrument. Reliability was assessed through test-retest analysis, internal consistency was measured using Cronbach's alpha, and exploratory factor analysis (EFA) was conducted to examine the instrument's underlying structure. Results Content and face validity analyses confirmed that the Greek version of the LyQLI is clear, concise, and user-friendly for patients with lymphedema. Construct validity was robust, with all Cronbach's alpha coefficients exceeding 0.70 across four identified factors. Among these, the "Function" factor demonstrated the greatest impact on quality of life. Convergent validity was excellent, as LyQLI factor scores showed significant correlations with the corresponding SF-36 scales. Test-retest reliability indicated high reproducibility, and correlations between LyQLI and SF-36 scales were consistently strong (Pearson's r > 0.3). Conclusion The Greek version of the LyQLI demonstrated excellent validity and reliability, confirming that it is a concise, easily comprehensible, and clinically practical instrument for evaluating quality of life among patients with lymphedema. Its psychometric properties support its use in both clinical practice and research settings, for the assessment of patient-reported outcomes in Greek-speaking populations.