Archived Policies - Medicine
Bioimpedance Devices for Detection of Lymphedema
Devices using bioimpedance (bioelectrical impedance spectroscopy) are considered experimental, investigational and unproven for use in the diagnosis, surveillance, or treatment of patients with lymphedema, including use in subclinical secondary lymphedema.
Secondary lymphedema of the upper extremity may develop following surgical treatment for breast cancer; it has been reported in approximately 25% to 50% of women following mastectomy. This can be a chronic, disfiguring condition. 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 newer techniques are being evaluated, including bioimpedance with use of bioimpedance spectroscopy (BIS) analysis, which uses resistance to electrical current in comparing the composition of fluid compartments. BIS is based on the theory that the amount of opposition to 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 with postoperative measurements, since existing differences between upper extremities (like the effects of a dominant extremity) may obscure early, subtle differences resulting from the initial accumulation of fluid. Bioimpedance has been proposed as one diagnostic test for this condition. Those who support the approach to diagnose subclinical disease believe that early treatment of subclinical lymphedema should result in less severe chronic disease.
One bioimpedance spectroscopy device is the ImpediMed L-Dex™ U400 cleared for marketing by the U.S. Food and Drug Administration (FDA) through the 510(k) process in 2007 (1) and in 2008. (2) According to the FDA letter, the device is “to aid in the clinical assessment of unilateral lymphedema of the arm in women. The device is not intended to diagnose or predict lymphedema of an extremity.”
Assessment of a diagnostic technology typically 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 outcomes (clinical utility).
Technical performance of a device is typically assessed with 2 types of studies, those that compare test measurements with a gold standard and those that compare results taken with the same device on different occasions (test-retest). While there is no absolute gold standard for diagnosis of lymphedema, the de facto gold standards are limb volume and/or limb circumference. These measurements have been judged to be both valid and reliable.
Diagnostic performance is evaluated by the ability of a test to accurately diagnose a clinical condition in comparison with the gold standard. The sensitivity of a test is the ability to detect a disease when the condition is present (true positive), while specificity indicates the ability to detect whether disease exists in patients who are suspected of disease but who do not have the condition (true negative). Evaluation of diagnostic performance, therefore, requires independent assessment by the 2 methods in a population of patients who are suspected of disease but who do not all have the disease.
Evidence related to improvement of clinical outcomes with use of this testing assesses the data linking use of a test to changes in health 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 trials are needed to demonstrate impact of the test on net health outcome.
The generally accepted approach to the diagnosis of lymphedema uses measurement of volume displacement and/or limb circumference. Most studies related to diagnosis involve these approaches. In contrast, the literature regarding bioelectrical impedance analysis is limited. In a study from Australia, Cornish and colleagues followed 102 patients after treatment for breast cancer. (3) Twenty patients developed lymphedema in the 24 months’ follow-up period, and in these 20 cases, multi-frequency bioelectrical impedance analysis (MFBIA) predicted the onset of the condition up to 10 months before the condition was diagnosed clinically. Estimates of the sensitivity and specificity were both approximately 100%. At the time of detection by MFBIA, only one of the patients had a positive test result from the total limb volume determined from the circumferential measures. In another study from Australia, Hayes and colleagues noted that the point prevalence of lymphedema varies according to the approach to diagnosis. (4) In this study, lymphedema status was assessed at 3-month intervals between 6 and 18 months post-surgery in a sample of Australian women with unilateral, invasive breast cancer, using 3 methods: bioimpedance spectroscopy (BIS), difference between sum of arm circumferences (SOAC), and self-report. Depending on the method, point prevalence ranged between 8 to 28%, with 1 in 5 to 2 in 5 women experiencing lymphedema at some point in time. In a U.S.-based study, Warren et al. evaluated 15 patients with upper- or lower-extremity secondary lymphedema documented by lymphoscintigraphy, along with 7 healthy controls using BIS analysis. (5) From this small study, the authors determined that BIS can be used as a tool for documenting the presence of lymphedema.
The literature on treatment shows variability among studies regarding response to therapy for secondary lymphedema. Some studies found that mild disease was more responsive to treatment; other studies did not. Similarly, when duration of symptoms was reported, there was no clear relationship between duration of the edema and response to treatment.
A publication by Czerniec and colleagues reported on measurement of lymphedema in a small group of patients, 33 with lymphedema and 18 without. (6) This study was to determine the relationship between physical methods of measuring lymphedema and self-reported swelling. Measurement techniques included self-report, BIS, perometer, and the truncated cone method. The authors noted that the physical measurement tools were highly reliable with high concordance (0.89 to 0.99, respectively). In this study, self-report correlated moderately with physical measurements (0.65 to 0.71, respectively) and was moderately reliable. The authors concluded that lymphedema assessment methods are concordant and reliable but not interchangeable.
In a study from Europe involving 55 women who had breast cancer and axillary node dissection, Boccardo and colleagues evaluated a preventive protocol for lymphedema. (7) The preventive group had volumetric (arm volume) measurements performed preoperatively and at 1, 3, 5, 12, and 24 months postoperatively. The protocol for this group included principles to minimize lymphedema risk, lymphoscintigraphy preoperatively and at 6 months postoperatively, and early management of the condition once identified. Clinically significant lymphedema was an increase of at least 200 mL from the preoperative difference between the two arms. Assessments at 2 years were completed for 89% of the 55 women who were randomly assigned to either preventive group or control. Of the 49 who were measured at 2 years, 10 (21%) were identified with secondary lymphedema with an incidence of 8% in the preventive group and 33% in controls. The authors noted that these prophylactic strategies appear to reduce the development of secondary lymphedema and alter its progression. This is a relatively small study, and the various interventions used may have each played a role in the outcome for this study.
A study by Stout Gergich and colleagues is frequently cited as support for early detection and treatment of subclinical lymphedema. (8) In this study, lymphedema was identified in 43 of 196 women who participated in a prospective breast cancer morbidity trial. Limb volume was measured preoperatively and at 3-month intervals after surgery using perimetry (another evolving technique). If an increase of greater than 3% in upper limb volume developed compared with the preoperative volume, a diagnosis of lymphedema was made and a compression garment intervention was prescribed for 4 weeks. Statistical analysis was a repeated-measures analysis of variance by time and limb (p<0.001) comparing the lymphedema cohort with an age-matched control group. In this study, the time to onset of lymphedema averaged 6.9 months postoperatively. The mean (+/-standard deviation [SD]) affected limb volume increase was 83 mL (+/-119 mL) at lymphedema onset compared with baseline. Of note, clinical lymphedema is generally felt to be apparent when 200 mL of fluid accumulates. After the intervention, a statistically significant mean 48 mL (+/-103 mL) volume decrease was realized. The mean duration of the intervention was 4.4 weeks. Volume reduction was maintained at an average follow-up of 4.8 months after the intervention. The authors concluded that a short trial of compression garments effectively treated subclinical lymphedema. This study does not answer the key question; that is, whether net health outcome was improved by early intervention. In addition, the role of novel diagnostic testing compared to the use of the de facto gold standard tests (limb volume or circumference) also needs to be evaluated.
A technology assessment performed under contract from Agency for Healthcare Research and Quality (AHRQ) by the McMaster University Evidence-based Practice Center was released in May 2010. (9) This report notes that in contrast to information about the techniques of circumferential measurement and volume displacement, there is too little evidence to draw conclusions about the reliability of other tests such as tonometry, ultrasound, lymphoscintigraphy, or bioimpedance. The report also notes that the studies do not allow conclusions about the potential impact of timing of the initial intervention.
A study published in 2011 by Smoot and colleagues reported on diagnostic test characteristics including sensitivity, specificity, and area under the receiver-operating-characteristic (ROC) curve for a number of tests used in the diagnosis of breast cancer-related lymphedema. (10) For this study, a total of 141 women were classified as having (n=70) or not having (n=71) breast cancer-related lymphedema (BCRL) based on past diagnosis by a health care provider. Areas under the curve for a number of bioimpedance measures and volume measures were in the 0.79 to 0.88 range, with overlap in confidence intervals. Given questions about the standard used for diagnosis and apparent lack of patients with subclinical lymphedema, this study provides little new information. Finally, in a study from Australia, Ward and colleagues concluded that the impedance ratio thresholds for early detection of lymphedema remain suitable for clinical use with present-day analyzers. (11)
There is minimal information about the technical and diagnostic performance of bioimpedance testing in the diagnosis (surveillance) of secondary 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). The approach to subclinical lymphedema (diagnosis and treatment) appears to be under active investigation. Thus, based on the current scientific evidence and because the impact on net health outcome is not known, use of this testing in the diagnosis or management of patients with known or suspected lymphedema is considered experimental, investigational and unproven.
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8/1/2012 Document updated with literature review. Coverage unchanged.
7/15/2010 New medical document. Devices using bioimpedance (bioelectrical impedance spectroscopy) are considered experimental, investigational and unproven for use in the diagnosis, surveillance, or treatment of patients with lymphedema, including use in subclinical secondary lymphedema. (Coverage is unchanged. This topic was previously addressed on MED202.018, Plethysmography.)
|Title:||Effective Date:||End Date:|
|Bioimpedance Devices for Detection of Lymphedema||10-15-2017||09-30-2018|
|Bioimpedance Devices for Detection of Lymphedema||06-01-2016||10-14-2017|
|Bioimpedance Devices for Detection of Lymphedema||03-15-2015||05-31-2016|
|Bioimpedance Devices for Detection of Lymphedema||04-15-2014||03-14-2015|
|Bioimpedance Devices for Detection of Lymphedema||08-01-2012||04-14-2014|
|Bioimpedance Devices for Detection of Lymphedema||07-15-2010||07-31-2012|