For the evaluation of body composition, a four-compartment (4C) model is considered as the gold standard. In the 4C model de body is divided into four compartments, namely fat-free mass (FFM), including total body water (TBW), bone mineral content (BMC) and proteins, and the fat mass (FM). However, these assessments are very costly and time intensive. The 4C model measurement is impractical because of the cost and necessary equipment. Recently, improvements in technologies and consequent assessment methodology are made. Nowadays, two-compartment (2C) methods are more commonly used thanks to the short-time demand and ease of use. The 2C model performs segmental estimates of fat mass (FM) and fat free mass (FFM). An example of a 2C model is bioelectrical impedance analysis (BIA). The 2C model is advantageous for tracking changes over time. Semi-portable multi-frequency bioelectrical impedance analysis (MF-BIA) devices may be a cost-effective and easy-to-use method as an alternative for the 4C model. The MF-BIA uses two or more frequencies to estimate body composition together with population-specific algorithms based on age, height, weight, gender and ethnicity. The MF-BIA uses the different levels of conductivity of the body’s tissues and fluids to estimate body composition. At low frequencies, only the extracellular fluid can be measured because the current is unable to pass through the cell membrane. Conversely, at high frequencies, the current can pass through the cell membrane, which allows the device to measure total body water.
The InBody 770 is such a MF-BIA device and is used by two predoctoral researchers of the CarEdOn research group.
Findings from the study of Bremer et al. suggest that in healthy adults, the InBody 770 may produce fairly good estimates of body composition (FM, and FFM) compared to a 4C model; %fat estimates resulted in greater error, yet still acceptable. The different models of body composition are displayed in the image below.
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The InBody 770 is a relatively new device, and its advantage is that it can measure the extracellular and intracellular fluid separate for each limb (i.e. four segments). The analysis of body composition with the InBody 770 only takes one minute. The subject must stand barefoot on four electrodes, corresponding with the soles of their feet. Besides this, the subject must hold the handles in both hands making contact with electrodes on the thumbs and palm of each hand. Previously, height, sex and age were entered into the software. The device collects weight and estimates parameters of the total body composition.
The body composition analysis with the InBody 770 improves the insights into the inner health of a patient. At the end of the assessment, a personalized result sheet is printed, which shows the components that are key to understanding more about his/her body composition. Another method that uses a multifrequency current is BioImpedance Spectroscopy (BIS). An example of the BIS is the SOZO device of the company Impedimed. However, the SOZO is not able to measure segmental body water. This device uses 256 frequencies to determine the extracellular fluid and the total body water. Together with a mathematical method, other parameters such as intracellular fluid, FM and FFM can be calculated instead of estimated.
Further, we would like to illustrate how the InBody 770 is used in different trials within the CarEdOn research group:
1) UroLymph trial
One of the aims of the UroLymph trial is to investigate the most accurate method to detect lymphoedema in the lower limb after radical prostatectomy or radical cystectomy with lymph node dissection (as treatment for prostate and bladder cancer respectively). Due to this dissection, whether or not in combination with radiotherapy, patients may develop lymphoedema of the foot/ feet, leg/ legs and of the genital region. An imbalance between the filtration rate out of the capillary bed and the resorption by the lymphatic vessels may lead to the accumulation of fluid in the interstitium. This acquired lymphoedema is also called secondary lymphoedema.
In the UroLymph trial patients are measured at 4 moments: 1) preoperatively (baseline), 2) 6 weeks after surgery, 3) 6 months after surgery and 4) 12 months after surgery. In the study, the InBody device is used to determine the extracellular fluid in the leg(s) or trunk. An example of a result sheet of the InBody 770 is shown in the image below.
The SOZO device is used as well. In this way, we will be able to compare the accuracy of detecting lower limb lymphoedema between both devices. Moreover, we also determine limb volume by performing circumference and water displacement measurements, we determine local water content by performing measurements with the MoistureMeterDC and the pitting test and the patients complete a questionnaire about the presence of swelling. So, at the end of the trial, we will have a clear answer on the question: ‘which method or combination of methods is most accurate to detect the development of lymphoedema of the lower limb in people after prostatectomy or radical cystectomy?’.
2) EffEx-HN trial
The second trial that is using the InBody 770, is the EffEx-HN trial. This is an effectiveness study about improving health-related quality of life with an individualized and supervised exercise program during the treatment of head neck cancer (HNC).
In this specific population, it is interesting to determine the presence of sarcopenia. Sarcopenia is defined as a skeletal muscle disorder, characterized by low muscle strength, low quality and low muscle volume. Patients with HNC are at higher risk of developing sarcopenia, mostly because of swallowing disability caused by the tumor and the side effects of the radiotherapy treatment. The prevalence rate of sarcopenia in this population ranges from 6.6% to 70.9%, depending on the cancer type, diagnostic procedures and cut-off values for sarcopenia. The sheet showing the outcomes of the evaluation with the InBody 770 device shows the Skeletal Muscle Index (SMI). The SMI is the ratio of the segmental FFM of the limbs to the height2. A ‘SMI’ lower than 5.5 kg/m2 and a SMI lower than 7 kg/m2 are considered cut-off values for sarcopenia, for women and men respectively.
Also weight loss, as one of the most characteristic signs of malnutrition, is common among the HNC population. The study of Langius et al. reveals that more than 10% weight loss during and directly after radiotherapy has a significant impact on quality of life in HNC patients, which is the primary outcome of the EffEx-HN trial. Besides, the muscle-fat analysis of the InBody 770 contains 3 components: skeletal muscle mass, weight and body fat mass. The length of each bar on the graph shows one of the 3 different body types: C-shape, I-shape and D-shape. A C-shaped patient has a shorter bar length for skeletal muscle mass than for weight and body fat mass. An I-shaped person has a balanced body composition, which means that their weight, skeletal muscle mass and body fat mass bars roughly form a straight line. A D-shaped person has a longer SMM bar than their weight and body fat mass bar. An example of a result sheet is shown in the image below.
In the EffEx-HN trial head and neck cancer patients are assessed at 5 time-points: 1) first week of radiotherapy treatment (baseline), 2) 6 weeks, 3) 12 weeks, 4) 6 months, 5) 12 months. The aim of the assessment via the Inbody device is giving an overview of the general body composition, following up the weight during and after treatment, determining whether sarcopenia is present and showing the body type of the patient.
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4. Michel Y.Jaffrin H. Body fluid volumes measurements by impedance: A review of bioimpedance spectroscopy (BIS) and bioimpedance analysis (BIA) methods. Medical Engineering & Physics. 2008;30(10):1257-69.
5. Steele ML, Janda M, Vagenas D, Ward LC, Cornish BH, Box R, et al. A Bioimpedance Spectroscopy-Based Method for Diagnosis of Lower-Limb Lymphedema. Lymphat Res Biol. 2020;18(2):101-9.
6. Y. Takenaka et al. Prognostic impact of sarcopenia in patients with head and neck cancer treated with surgery or radiation: A meta-analysis, PLoS One. 2021; 16(10), doi: 10.1371/journal.pone.0259288
7. JAE. Langius et al., More than 10% weight loss in head and neck cancer patients during radiotherapy is independently associated with deterioration in quality of life, Nutr. Cancer, 2013; 65(1):76-83. doi: 10.1080/01635581.2013.741749.
Written by Charlotte Van Calster & Kaat Van Aperen