Psychometric Evaluation of a Brazilian Version of the Lymphedema Functioning, Disability and Health Questionnaire for Lower Limb Lymphedema in Patients After Cancer Treatment.

Background: The aim of this study was to evaluate psychometric properties of the Lymphedema Functioning, Disability and Health Questionnaire for lower limb lymphedema (Lymph-ICF-LL) in Brazilian patients with secondary lower limb lymphedema after cancer treatment. Methods and Results: A diagnostic test study was performed in 30 patients with lower limb lymphedema. To assess the reliability, the intraclass correlation coefficient (ICC) was analyzed through test-retest, Cronbach alpha coefficient, magnitude of intrasubject variability by standard error of measurement (SEM), and smallest real difference (SRD). To assess the face and content validity, a specific questionnaire was applied to assess the clarity of the scoring system and comprehensiveness of questions. To assess construct validity, correlations between the final Brazilian version of the Lymph ICF-LL and the quality of life questionnaire SF-36 (36-Item Short Form Health Survey Questionnaire) were analyzed. The ICCs and general internal consistency scores of Lymph-ICF-LL were high (ICCs >0.90 and the Cronbach alpha coefficient >0.90, respectively). Measurement variability between the tests was acceptable (SEM 5.9) with SRD of 16.4. Face and content validity were considered excellent by the patients as the scoring system was clear and questions were understandable for 97% and 90% of the patients, respectively. Construct validity was classified as good and all hypotheses for assessing convergent validity were accepted (medium to strong correlation, from -0.69 to -0.84). Conclusion: The Brazilian version of the Lymph-ICF-LL is a reliable and valuable instrument for assessing Brazilian patients with secondary lower limb lymphedema associated with cancer treatment.