L-dex ratio in detecting breast cancer-related lymphedema: reliability, sensitivity, and specificity

Advances in bioelectrical impedance analysis (BIA) permit the assessment of lymphedema by directly measuring lymph fluid changes. The objective of the study was to examine the reliability, sensitivity, and specificity of cross-sectional assessment of BIA in detecting lymphedema in a large metropolitan clinical setting. BIA was used to measure lymph fluid changes. Limb volume by sequential circumferential tape measurement was used to validate the presence of lymphedema. Data were collected from 250 women, including healthy female adults, breast cancer survivors with lymphedema, and those at risk for lymphedema. Reliability, sensitivity, specificity and area under the ROC curve were estimated. BIA ratio, as indicated by L-Dex ratio, was highly reliable among healthy women (ICC=0.99; 95% CI = 0.99 - 0.99), survivors at-risk for lymphedema (ICC=0.99; 95% CI = 0.99 - 0.99), and all women (ICC=0.85; 95% CI = 0.81 - 0.87); reliability was acceptable for survivors with lymphedema (ICC=0.69; 95% CI = 0.54 to 0.80). The L-Dex ratio with a diagnostic cutoff of >+7.1 discriminated between at-risk breast cancer survivors and those with lymphedema with 80% sensitivity and 90% specificity (AUC=0.86). BIA ratio was significantly correlated with limb volume by sequential circumferential tape measurement. Cross-sectional assessment of BIA may have a role in clinical practice by adding confidence in detecting lymphedema. It is important to note that using a cutoff of L-Dex ratio >+7.1 still misses 20% of true lymphedema cases, it is important for clinicians to integrate other assessment methods (such as self-report, clinical observation, or perometry) to ensure the accurate detection of lymphedema.