Measurement Properties and Determinants of the 6-Minute Walk Test in Patients with Lower Limb Lymphedema

Background: The aim of this study was to investigate the validity and reliability and identify determinants of the 6-minute walk test (6MWT) in patients with lower limb lymphedema (LLL). Methods and Results: The study included 28 patients with LLL and 28 healthy subjects. To investigate the convergent validity and determinants of the 6MWT, patients were assessed using the following measurements: circumference measurement for lymphedema severity, hand-held dynamometry for muscle strength, time up and go for functional mobility, five-time sit-to-stand test for functional lower extremity strength, Lower Extremity Functional Scale for lower extremity functionality, Lymphedema Life Impact Scale for quality of life, and International Physical Activity Questionnaire-Short Form for physical activity level. The test-retest reliability of the 6MWT was assessed using intraclass correlation coefficients (ICCs). 6MWT, a test-retest reliability analysis was carried out with 28 patients within 3-7 days. The receiver operating characteristic (ROC) curve was employed to determine the cut-off point of 6MWT. The test-retest reliability of 6MWT was detected as excellent (ICC [95%] 0.93 [0.87-0.97]). Significant correlations were found between the 6MWT health-related and disease-specific parameters, indicating sufficient convergent validity (r ≥ 0.3). The ROC curve indicated a cut-off point of 504 meters (area under the curve [AUC] 0.712 [95%CI: 0.575-0.849]). Multiple linear regression analysis demonstrated that lymphedema severity, hip abduction muscle strength, and lower limb functionality were the predictors of 6MWT. Conclusions: The 6MWT has been shown to be a reliable and valid tool for assessing the functional capacity of patients with LLL.