Reliability and validity testing of the Korean translation of lymphedema quality of life questionnaire (LYMQOL) for lower limb lymphedema

Purpose This study aimed to translate the Lymphedema Quality of Life Questionnaire-leg into Korean (K-LYMQOL-leg) and test its reliability and validity. Materials and methods The LYMQOL-leg was translated forward and backward from English to Korean. Fifty-five patients with lower limb lymphedema completed the K-LYMQOL-leg and the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC-QLQ-C30) at the first visit, and the K-LYMQOL-leg was re-administered within a week. Reliability was tested by calculating the intraclass correlation coefficient (ICC) and the Cronbach's alpha for each domain. Face validity was evaluated, and concurrent validity was verified by comparing the K-LYMQOL-leg domain scores with the corresponding EORTC-QLQ-C30 and limb volume scales. The known-group construct validity was then assessed. Results Excellent reliability was confirmed by internal consistency (Cronbach's alpha coefficient, 0.851-0.878) and test-retest reliability (ICC, 0.901-0.936) in the four domains. A significant correlation was confirmed in the appearance domain with limb volume (r = 0.424) and in the other domains [function, symptom, and mood], with the EORTC-QLQ-C30 scales (r = -0.779, 0.712, and -0.783). Known-group validity was confirmed in all four domains. Conclusions The K-LYMQOL-leg verified in this study can be used in clinical practice to evaluate the Quality of Life (QOL) of patients with lymphedema or in research as an outcome.