Medical Policy: 06.01.31
Original Effective Date: September 2013
Reviewed: April 2020
Revised: April 2020
This policy contains information which is clinical in nature. The policy is not medical advice. The information in this policy is used by Wellmark to make determinations whether medical treatment is covered under the terms of a Wellmark member's health benefit plan. Physicians and other health care providers are responsible for medical advice and treatment. If you have specific health care needs, you should consult an appropriate health care professional. If you would like to request an accessible version of this document, please contact customer service at 800-524-9242.
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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.
There has been an interest in using whole body dual x-ray absorptiometry (DXA) and bioelectrical impedance analysis (BIA) in the clinical care setting rather than a research setting.
Body composition measurements can be used to quantify and assess the relative proportions of specific body compartments such as fat and lean mass (e.g., bones, tissues, organs, muscles). These measurements may be more useful in informing diagnosis, prognosis, or therapy than standard assessments (e.g., body weight, body mass index) that do not identify the contributions of individual body compartments or their particular relationships with health and disease. While these body composition measurements have been most frequently utilized for research purposes, they may be useful in clinical settings to:
A variety of techniques has been researched, including most commonly, anthropomorphic measures, bioelectrical impedance analysis (BIA), and dual-energy x-ray absorptiometry (DXA). All of these techniques are based in part on assumptions about the distribution of different body compartments and their density, and all rely on formulas to convert the measured parameter into an estimate of body composition. Therefore, all techniques will introduce variation based on how the underlying assumptions and formulas apply to different populations of subjects (i.e., different age groups, ethnicities, or underlying conditions).
Routinely, anthropomorphic measures are sufficient to estimate adiposity in a clinical setting. Anthropometric measurements include the following:
The measurement sites vary depending on the specific skinfold testing protocol being used, but typically include the following seven locations on the body:
According to the American College of Sports Medicine, when performed by a trained, skilled tester, skinfold measurements of body fat are up to 98% accurate. However, due to new technologies available such as electrical impedance methods and scales that measure body composition instead of directly measuring skinfolds, skinfold testing may not be utilized like it once was in clinical practice setting.
Underwater weighing requires the use of a specially constructed tank in which the subject is seated on a suspended chair. The subject is then submerged in the water while exhaling. While valued as a research tool, weighing people underwater is obviously not suitable for routine clinical use. This technique is based on the assumption that the body can be divided into 2 compartments with constant densities: adipose tissue, with a density of 0.9 g/cm3, and lean body mass (ie, muscle and bone), with a density of 1.1 g/cm3. One limitation of the underlying assumption is the variability in density between muscle and bone; for example, bone has a higher density than muscle, and bone mineral density varies with age and other conditions. In addition, the density of body fat may vary, depending on the relative components of its constituents (eg, glycerides, sterols, glycolipids).
Magnetic resonance imaging (MRI) or computed tomography (CT) can be used to measure visceral adipose tissue. The technique usually quantifies adipose tissue in a single slice cross section at the level of the L4/L5 lumbar disc. The subcutaneous fat (outside the abdominal musculature) may be measured in the same image. These measures of visceral adiposity correlate with insulin resistance, triglycerides, hepatic steatosis, and other components of the metabolic syndrome. This technique is used for research in obesity and metabolic disease and does not contribute to clinical care.
Bioelectrical impedance is based on the relationship between the volume of the conductor (i.e. human body), the conductor’s length (i.e. height), the components of the conductor (i.e. fat and fat-free mass), and its impedance. Estimates of body composition are based on the assumption that the overall conductivity of the human body is closely related to lean tissue. The impedance value is then combined with anthropomorphic data to give body compartment measures. The technique involves attaching surface electrodes to various locations on the arm and foot. Alternatively, the patient can stand on pad electrodes.
Using low dose x-rays different energy levels, whole body dual x-ray absorptiometry (DXA) measure lean tissue mass, total and regional body fat, as well as bone density. DXA scans have become a tool for research body composition, but there has been an interest in using DXA in the clinical care setting rather than a research setting.
While the cited techniques above assume 2 body compartments, DXA can estimate 3 body compartments consisting of fat mass, lean body mass, and bone mass. DXA systems use a source that generates x-rays at 2 energies. The differential attenuation of the 2 energies is used to estimate bone mineral content and the soft tissue composition. When 2 x-ray energies are used, only 2 tissue compartments can be measured; therefore, soft tissue measurements (i.e. fat and lean body mass) can only be measured in areas in which no bone is present. DXA also has the ability to determine body composition in defined regions (i.e. the arms, legs, and trunk). DXA measurements are based in part on the assumption that the hydration of fat-free mass remains constant at 73%. Hydration, however, can vary from 67% to 85% and can be variable in certain disease states. Other assumptions used to derive body composition estimates are considered proprietary by DXA manufacturers.
The purpose of whole body dual x-ray absorptiometry (DXA) body composition studies is to improve the diagnosis and management of patients who have clinical condition associated with abnormal body composition.
The relevant population of interest are individuals with clinical conditions associated with abnormal body composition.
The test being considered is DXA body composition studies administered in an outpatient setting.
The following practices are currently being used to make decisions in this patient group: standard of care without DXA or an alternative method of body composition analysis.
The general outcomes of interest include symptom management and change in disease status. For patients at risk of osteoporosis outcomes of interest would include fracture incidence. For patients with HIV who are treated with antiretroviral therapy, outcomes of interest would include lipodystrophy.
For individuals who have a clinical condition associated with abnormal body composition who receive whole body dual x-ray absorptiometry (DXA) body composition studies, the evidence includes systematic reviews and several cross-sectional studies comparing DXA with other techniques. The available studies were primarily conducted in research settings and often used DXA body composition studies as a reference standard; these studies do not permit conclusions about the accuracy of DXA for measuring body composition. A systematic review exploring the clinical validity of DXA measurements against reference methods for the quantification of intra-abdominal adipose tissue raised concerns for precision and reliability. More importantly, no studies were identified in which DXA body composition measurements were actively used in patient management. The evidence is insufficient to determine the effects of the technology on net health outcomes.
The purpose of the serial whole body dual x-ray absorptiometry (DXA) body composition studies in patients who have a clinical condition managed by monitoring body composition changes over time is to improve disease management.
The relevant patient population of interest are individuals with clinical conditions managed by monitoring body composition changes over time.
The test being considered is serial DXA body composition studies.
he following practices are currently being used to make decisions in this patient group: standard of care without DXA or an alternative method of body composition analysis.
The general outcomes of interest include symptom management and change in disease status. For patients with anorexia nervosa, outcomes of interest would include disease -related mortality and rate of remission.
For individuals who have a clinical condition managed by monitoring changes in body composition over time who receive whole body dual x-ray absorptiometry (DXA) composition studies, the evidence includes several prospective studies monitoring patients over time. The studies used DXA as a tool to measure body composition and were not designed to assess the accuracy of DXA. None of the studies used DXA findings to make patient management decisions or addressed how serial body composition assessment might improve health outcomes. The evidence is insufficient to determine the effects of the technology on net health outcomes.
During bioelectrical impedance analysis (BIA) electrodes are attached to the hands and feet of the individual being evaluated. Certain electrodes apply the electrical current while other select and measure the output without the current being felt by the individual. Muscle, having higher water content than adipose tissue (fat), should have lower impedance. BIA has been proposed as a method for whole body composition or body fat composition assessment in conjunction with annual wellness examinations or weight management evaluations with an individual’s health care provider. Variables such as testing methods, types of equipment as well has health factors of the individual being tested are known to affect results.
The purpose of serial bioelectrical impedance analysis (BIA) studies in patients who have a clinical condition managed by monitoring body composition changes over time is to improve disease management.
The relevant patient population of interest are individuals with clinical conditions managed by monitoring body composition changes over time.
The test being considered is serial bioelectrical impedance analysis (BIA) studies.
The following practices are currently being used to make decisions in this patient group: standard of care without bioelectrical impedance analysis (BIA) or an alternative method of body composition analysis.
The general outcomes of interest include symptom management and change in disease status.
Based on review of the peer reviewed medical literature, there is currently no established role for whole body bioelectrical impedance analysis (BIA) for individuals who have a clinical condition associated with abnormal body composition or who have a clinical condition managed by monitoring changes in body composition over time. Currently no studies have been identified in the literature in which BIAmeasurements were actively used in patient management, and studies have not reported data demonstrating the impact of body composition assessment on net health outcomes. Further studies are needed to assess the clinical value of this testing. The evidence is insufficient to determine the effects of the technology on net health outcomes.
In 2015, The International Society for Clinical Densitometry (ISCD) updated thier adult position statement which included a statement on the use of DXA body composition. The statement included the following ISCD position regarding the use of DXA total body composition with regional analysis in the following condtions:
The position statement also included that pregnancy is a contraindication to DXA body composition.
In 2018, the USPSTF updated their 2012 recommendation for screening all adults for obesity to the following. Clinicians should offer or refer adults with body mass index (BMI) of 30 kg/m2 or higher to intensive, multicomponent behavioral interventions.
Waist circumference may be an acceptable alternative to BMI measurement in some patient populations.
The USPSTF commissioned a systematic evidence review to update its 2012 recommendation on screening for obesity in adults. Because screening for obesity is now part of routine clinical practice, it was not a focus of this review.
In 2017, the USPSTF recommends that clinicians screen for obesity in children and adolescents 6 years and older and offer or refer them to comprehensive, intensive behavioral interventions to promote improvements in weight status.
Body mass index measurement is the recommended screening test for obesity. Body mass index percentile is plotted on growth charts, such as those developed by the CDC, which are based on US-specific, population-based norms for children 2 years and older. Obesity is defined as an age- and sex-specific BMI in the 95th percentile or greater.
In 2013, the ACC/AHA/TOS issued a guideline for the management of overweight and obesity in adults and the summary of recommendations for obesity state, “identifying patients who need to lose weight (BMI and waist circumference), measure height and weight and calculate BMI at annual visits or more frequently. Measure weight circumference at annual visits or more frequently in overweight and obese adults.” (E-Expert Opinion)
This guideline does not mention the use of whole body dual x-ray absorptiometry (DXA) or bioelectrical impedance analysis (BIA) in the assessment and management of overweight and obese adults.
In 2014, National Institute for Health and Clinical Excellence (NICE) issued a guideline on obesity: identification, assessment and management. The guideline included the following:
Body composition software for several bone densitometer systems has been approved by the U.S. Food and Drug Administration through the premarket approval process. They include the Lunar iDXA systems (GE Healthcare), Hologic DXA systems (Hologic), and Norland DXA systems (Swissray).
The use of whole body dual x-ray absorptiometry (DXA) and bioelectrical impedance analysis (BIA) for body composition studies is considered investigational for all indications. There is insufficient evidence to support a conclusion concerning the net health outcomes or benefits associated with this testing.
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