Cross-cultural validation and responsiveness of the French version of the lymphedema functioning, disability and health questionnaire for lower limb lymphedema (Lymph-ICF-LL)

Purpose To investigate reliability, validity and responsiveness of the French Lymph-ICF-LL questionnaire for lower limb lymphedema (LLL).Materials and methods In this observational study, patients with stable LLL completed the Lymph-ICF-LL twice with an interval of 1–2 days. Test-retest reliability was determined with Intraclass Correlation Coefficients (ICC), standard error of measurement and smallest real difference. Internal consistency was analyzed with Cronbach’s alpha (α). To assess construct validity, Spearman rank correlation coefficients between the Lymph-ICF-LL and SF-36 were calculated. For responsiveness, the Global Perceived Effect scale (GPE) and Lymph-ICF-LL were completed after 2 months. Other patients completed the Lymph-ICF-LL at start of an intensive treatment and 1 month later together with the GPE. Wilcoxon signed rank test, Standardized Response Mean, Minimal Clinically Important Difference and correlations between the change on Lymph-ICF and GPE were determined. (NCT07075549)Results For the total score, excellent reliability (ICC = .94) and good internal consistency (α = .86) were found. Convergent validity was confirmed with significant moderate correlations with SF-36 (r = -0.48−-0.72; p<.001). A significant change in total score was found after intensive treatment (p=.017). Significant correlations between change scores and GPE were obtained (p < .05).Conclusions The French Lymph-ICF-LL is a reliable, valid and responsive questionnaire to evaluate lymphedema-specific quality of life in patients with LLL.