Medical Policy: 02.01.57
Original Effective Date: January 2017
Reviewed: January 2017
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This Medical Policy document describes the status of medical technology at the time the document was developed. Since that time, new technology may have emerged or new medical literature may have been published. This Medical Policy will be reviewed regularly and be updated as scientific and medical literature becomes available.
Lymphedema is caused by an abnormality of the lymphatic system leading to excessive build of up tissue fluid that forms lymph, known as interstitial fluid. Stagnant lymph fluid contains protein and cell debris that causes swelling of affected tissues. Left untreated, lymphedema leads to chronic inflammation, infection and hardening of the skin that, in turn, results in further lymph vessel damage and distortion of the shape of affected body parts.
Lymphedema is progressive and early diagnosis leads to more effective treatment, the diagnosis of lymphedema at the earliest possible stage is very important. Measures of limb (arm and leg) volume have been the standard way of detecting lymphedema for years and have been shown to be accurate when properly done. Volume is measured by 3 main methods: tape measurements, perometry and water displacement. The use of bioimpedance which uses resistance to electrical current in comparing the composition of fluid compartments has been proposed as a tool to assist in the clinical assessment of lymphedema by a medical provider.
Bioimpedance spectroscopy (BIS) is done by passing a small painless electrical current through the limb and measuring the resistance to current (impedance). The machine uses certain electrical current frequencies to determine if more fluid exists as compared to the contralateral limb. It does this by comparing the difference in resistance to electricity passed through interstitial fluid compared to intracellular fluid. BIS is currently done on the whole limb since the resistance to current flow for standard technique is calculated to the length of the body part. The higher the water content in the interstitial tissue, the lower the resistance (impedance).
Lymphedema is a condition that develops slowly and once present is usually progressive. Most lymphedema in the United States is secondary lymphedema. Secondary lymphedema occurs from damage to the lymphatic system, commonly from cancer and its treatment but also from trauma to the skin such as from burns or infections. Lymphedema after breast cancer has been studied the most, but lymphedema can occur as a result of other cancers, including melanoma, gynecologic cancer, head and neck cancer and sarcoma.
Secondary lymphedema of the upper extremity may develop following treatment for breast cancer; it has been reported in approximately 25% to 50% of women following mastectomy. It results from lymphatic dysfunction or disruption and can be difficult to accurately diagnose and manage. One challenge is identifying the presence of clinically significant limb swelling through simple noninvasive methods. Many techniques have been used for documenting lymphedema including measuring differences in limb volume (volume displacement) and limb circumference. A number of new techniques are being evaluated, including bioimpedance with use of bioimpedance spectroscopy (BIS) analysis, which uses resistance to electrical current to compare the composition of fluid compartments. BIS is based on theory that the level of opposition to the flow of electric current (impedance) through the body is inversely proportional to the volume of fluid in the tissue. In lymphedema, with the accumulation of excess interstitial fluid, tissue impedance decreases.
The detection of subclinical lymphedema, that is, the early detection of lymphedema before clinical symptoms become apparent, is another area of study. Detection of subclinical lymphedema (referred to as stage 0 lymphedema) is problematic. Subclinical disease may exist for months or years before overt edema is noted. This approach generally involves comparison of preoperative (i.e. baseline) with postoperative measurements, because existing differences between upper extremities (like the effects of a dominate extremity) may obscure early, subtle differences resulting from the initial accumulation of fluid. Bioimpedance has been proposed as a diagnostic tests for this condition. Those who support this approach to diagnose subclinical disease believe that early treatment of subclinical lymphedema should result in less severe chronic disease.
Assessment of a diagnostic technology focuses on 3 parameters: 1) technical performance; 2) diagnostic performance (sensitivity, specificity, and positive and negative predictive value) in appropriate populations of patients; and 3) demonstration that the diagnostic information can be used to improve patient’s outcomes (clinical utility). While in some cases, tests can be adequately evaluated using technical and diagnostic performance, when a test identifies a new or different group of patients with a disease, randomized controlled trials (RTCs) are needed to demonstrate impact of the test on the net health outcome.
Technical performance of a device is typically assessed with 2 types of studies; those that compare test measurements with a criterion standard and those that compare results taken with the same device on different occasions (test-retest). While there is no absolute criterion standards for diagnosis of lymphedema, the de facto criterion standard are limb volume and/or limb circumference.
There were two studies found that addressed technical performance of bioimpedance devices:
A technology assessment on the diagnosis and treatment of secondary lymphedema, performed under contract from Agency for Healthcare Research and Quality (AHRQ) by McMaster University Evidence-based Practice Center, was released in May 2010. Most of the diagnostic accuracy and treatment studies were conducted in persons with history of breast cancer. The AHRQ assessment identified 8 studies that reported the sensitivity and specificity of tests to diagnose secondary lymphedema and two of the 8 studies on diagnostic performance of devices to detect secondary lymphedema evaluated bioimpedance devices. Overall, the investigators concluded that based on the evidence, limb and volume circumference are the de facto gold standard tests from which to assess the presence of secondary lymphedema. Although validity assessment suggests good interchangeability between different measures of limb volume or circumference, the heterogeneity of the evidence was to substantial to enable the drawing of conclusions about the type of measure that would be the most appropriate for diagnosing secondary lymphedema.
In 2015, a prospective validation study by Barrio et. al. was performed comparing bioimpedance
(L-Dex) and volume displacement measurements in a cohort of breast cancer patients at risk for lymphedema. Between 2010 and 2014 a total of 223 breast cancer patients were enrolled. Thirty seven patients were excluded, leaving a sample size of 186. Prior to surgery participants received baseline volumetric measurements with bioimpedance device (L-Dex) and volume displacement (VD, the reference standard). Patients then had regular follow-up volumetric measurements every 3 to 6 months for 3 years. At a median follow up of 18.2 months, 152 patients were normal, 25 had an abnormal L-Dex and 9 developed lymphedema without a prior L-Dex abnormality. Of the 25 abnormal L-Dex patients, 4 progressed to lymphedema, for a total of 13 patients with lymphedema. Evaluating all time points, 186 patients had 829 follow-up measurements. Sensitivity and specificity of L-Dex compared with VD were 75 and 93%. There was no correlation between change in VD and change in L-Dex at 3 months (r = 0.31) or 6 months (r = 0.21). The authors concluded that VD and bioimpedance demonstrated poor correlation with inconsistent overlap of measurements considered abnormal. Of patient with abnormal L-Dex few progressed to lymphedema, most patients with lymphedema did not have prior L-Dex abnormality. Further studies are needed to understand the clinical significance of bioimpedance.
Another 2015 prospective study Blaney et. al. examined the feasibility of a breast cancer related lymphedema (BCRL) screening program, investigating the efficacy of bioimpedance analysis (BIA) compared to circumferential measurements (CM) in detecting BCRL. This was a 12 month prospective feasibility study and participants were recruited from two diagnostic breast clinics. Pre-surgical assessments were conducted, and participants were followed up at quarterly intervals. BIA and CM measurements were conducted at all time points. An L-Dex score of > 10 or a 10-U increase from baseline or a > 5% increase in proximal, distal or total percentage volume difference (PVD) from baseline was indicative of BCRL. Information was collected on subjective symptoms, potential risk factors, demographics and medical data. Feasibility was based on uptake and retention. One hundred twenty six participants were recruited with an attrition rate of 16.2%. Participants mean age was 59 years with the majority having stage I (63.9%), infiltrating ductal carcinoma (87.4%). 31.6% were identified has having BCRL, 90.3% detected by CM and 35.5% by BIA (p = < 0.0001). The authors concluded no significant correlation between BIA and CM. Work needs to continue to establish the most effective screening tool and the natural behavior of BCRL within the first year post surgery.
The ideal study design is an RCT comparing health outcomes in patients who are managed with and without the use of bioimpedance devices. No RTCs were identified. However, there was one controlled observational study comparing clinical lymphedema rates in patients managed with and without bioimpedance analysis. The 2014 study by Soran et. al. involved prospective detection of subclinical lymphedema in 186 patients diagnosed with breast cancer undergoing axillary lymph node dissection (ALND) who were managed with L-Dex or tape measurement of limb circumference (circumferential arm measurements). Baseline measurements were obtained and at 3-6 month intervals for 5 years. Subclinical lymphedema was defined as L-Dex value outside the normal range or that increased at least 10 units from baseline. Patients diagnosed with subclinical lymphedema received short term physical therapy, compression garments, and education about exercise, elevation, infection precautions, BMI and hand usage. A total of 180 women were included in the analysis. Seventy-two women had both preoperative bioimpedance and tape measurements (preoperative group). Forty-four women had preoperative bioimpedance and tape measurements but only had tape measurements postoperatively (control group). The remaining sixty-four women and postoperative bioimpedance and tape mesurements, but no preoperative measurements (no preoperative group). The authors compared demographic and clinical characteristics of the preoperative and control groups and of the preoperative and postoperative groups; they did not identify any statistically significant differences.
In the preoperative group, 28 of 72 women (36%) were diagnosed with subclinical lymphedema and referred for treatment; 2 women progressed to clinical lymphedema. In the control group, 16 women (36%) developed clinical lymphedema during follow up. A limitation of the study is that there was no alternative method for detecting subclinical lymphedema in the control group so they could receive treatment early. Moreover, the women were not randomized to a treatment group and complete information (pre and post-operative measures of lymphedema) was available for only a subset of the total population.
This study had several limitations, including non-randomized design, lack of blinding, lack of complete information on a substantial number of patients in the study, and lack of a systematic method for diagnosing lymphedema in the control group. The authors reported a significantly lower rate of clinical lymphedema in patients who were managed with bioimpedance analysis (BIA) and who received treatment for subclinical lymphedema. Additional studies to confirm these findings are needed, especially RCTs and trials that include an alternative method for early or subclinical lymphedema detection.
The evidence for bioimpedance devices in individuals who have known or suspected lymphedema includes several prospective studies on diagnostic accuracy and a controlled observational study evaluating clinical utility. Recent diagnostic accuracy studies found a poor correlation between bioimpedance analysis and the reference standard (volume displacement or circumferential measurement). There are no randomized controlled trials evaluating the clinical utility of bioimpedance devices in the management of patients with lymphedema or at high risk of developing lymphedema. The single prospective comparative study found a significantly lower rate of clinical lymphedema in patients managed with bioimpedance devices. Limitations of this study include the retrospective design, lack of randomized or blinding, and lack of systematic method of detecting early or subclinical lymphedema in the control group. The evidence is insufficient to determine the effects of this technology on net health outcomes and is considered investigational.
In 2007, the ImpediMed L-Dex U400 was cleared for marketing by the U.S. Food and Drug Administration (FDA) through the 510(k) process as an aid in the clinical assessment of unilateral lymphedema in the arms in women. It is not intended to diagnose or predict lymphedema. It is a tool to assist in the clinical assessment of lymphedema by a medical provider. L-Dex values that lie outside the normal range may indicate early signs of lymphedema and values that have changed +10 L-Dex units from baseline may also indicate early lymphedema.
Devices using bioimpedance (bioimpedance spectroscopy) are considered investigational for use in the detection, assessment, diagnosis, management or surveillance of individuals with known or suspected lymphedema.
There is minimal information about the technical and diagnostic performance of bioimpedance testing in the diagnosis of lymphedema; especially for subclinical disease. In addition, there are no data from comparative clinical trials that demonstrate the impact of this test (bioimpedance) on clinical outcomes (clinical utility). Therefore, based on the current scientific evidence and because the impact on net health outcome is not known, use of this testing in the detection, assessment, diagnosis, management or surveillance of patients with known or suspected lymphedema is considered investigational.
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January 2017 - New Policy
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