L-Dex ratio in detecting and diagnosing breast cancer-related lymphedema: Reliability, sensitivity, and specificity.

Abstract

Advances in bioelectrical impedance analysis (BIA) permit the assessment of lymphedema by directly measuring lymph fluid changes. The purpose 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 cutoff point 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.

Diagnosis of Upper-Quadrant Lymphedema Secondary to Cancer: Clinical Practice Guideline From the Oncology Section of APTA

“…These measures are compared with previously established baseline measures or normative standards for quantifying lymphedema. Normal L-Dex scores lie between −10 and +10, which is equivalent to an impedance ratio range of 0.935 to 1.139 for at-risk dominant arms and 0.862 to 1.006 for at-risk nondominant arms, calculated as 3 standard deviations from the mean normative data 41. Scores outside this range are indicative of lymphedema.…”

“…Newman et al45 found that BIA has the precision capable of detecting (1.65%-1.86%) the onset of extracellular fluid accumulation indicative of early development of lymphedema. Test-retest reliability using the Imp XCA analyzer, a clinical BIA device, demonstrates strong agreement in the healthy and at-risk groups (ICC = 0.99) but only fair agreement in the group with known breast cancer–related lymphedema (ICC = 0.69) 41. Concurrent validity has been studied using a variety of assessment methods involving both clinical and research models of BIA devices.…”

“…Variances in study results were attributed to differences in the BIA device used and stages of lymphedema examined. Bioimpedence analysis may not capture tissue changes such as fibrosis or adipose infiltration that are seen in later-stage lymphedema 41. Adequate evidence exists to support the use of both research and clinical BIA models; thus, it is recommended that multifrequency or spectroscopy BIA be used in early-stage and at-risk breast cancer survivors.…”

Diagnosis of upper limb lymphedema: development of an evidence-based approach

“…These thresholds, like those derived for BIS [6], account for limb dominance and have been set at three standard deviations (3SD) above the mean of a control population. However, it has been suggested that the 3SD approach may be overly conservative [8,9]. Furthermore, which of these tools and thresholds best identify LE is unknown, as comparison against a reasonable reference standard has not been undertaken.…”

Bilateral Changes in Deep Tissue Environment After Manual Lymphatic Drainage in Patients with Breast Cancer Treatment-Related Lymphedema

“…12 The L-Dex ratio is reported as a standardized measure of the ratio of the impedance of extracellular water in the affected limb compared to the unaffected limb. 13 Qualitative and quantitative MRI measures of tissue structure MRI measurements were performed at 3 Tesla (Philips Medical Systems, Best, The Netherlands) using dual-channel body coil radiofrequency transmission and a 16-channel torso coil for reception. The qualitative structural MRI protocol was optimized in prior work 14 and consisted of custom diffusionweighted-inversion-with-background-suppression imaging for large axillary node identification (spatial resolution = 3 · 3 · 5 mm; b-value = 800 s/mm 2 ; TR/TE/TI = 7528/54/ 260 ms), T 1 -weighted multipoint DIXON (mDIXON) for tissue and node structure (3D-gradient-echo; TR = 3.4 ms; spatial resolution = 1.0 · 0.74 · 2.5 mm), high-spatial resolution fat-suppressed T 2 -weighted MRI for node structure visualization (turbo-spin-echo; TR = 3500 ms; TE = 60 ms; spatial resolution = 0.4 · 0.5 · 5 mm).…”