BackgroundThere is no gold standard in body composition measurement in pediatric patients with obesity. Therefore, the aim of this study was to investigate if there are any differences between two bioelectrical impedance analysis techniques performed in children and adolescents with obesity.MethodsData were collected at the Department of Pediatrics and Adolescent Medicine in Vienna from September 2015 to May 2017. Body composition measurement was performed with TANITA scale and BIA-BIACORPUS.ResultsIn total, 38 children and adolescents (age: 10–18 years, BMI: 25–54 kg/m2) were included. Boys had significantly increased fat free mass (TANITA p = 0.019, BIA p = 0.003), total body water (TANITA p = 0.020, BIA p = 0.005), and basal metabolic rate (TANITA p = 0.002, BIA p = 0.029). Girls had significantly increased body fat percentage with BIA (BIA p = 0.001). No significant gender differences of core abdominal area have been determined. TANITA overestimated body fat percentage (p < 0.001), fat mass (p = 0.002), and basal metabolic rate (p < 0.001) compared to BIA. TANITA underestimated fat free mass (p = 0.002) in comparison to BIA. The Bland Altman plot demonstrated a low agreement between the body composition methods.ConclusionsLow agreement between TANITA scale and BIA-BIACORPUS has been observed. Body composition measurement should always be performed by the same devices to obtain comparable results. At clinical routine due to its feasibility, safety, and efficiency, bioelectrical impedance analysis is appropriate for obese pediatric patients.Trial registrationClinicalTrials NCT02545764. Registered 10 September 2015.

(1) Background: The determination of body composition is an important method to investigate patients with obesity and to evaluate the efficacy of individualized medical interventions. Bioelectrical impedance-based methods are non-invasive and widely applied but need to be validated for their use in young patients with obesity. (2) Methods: We compiled data from three independent studies on children and adolescents with obesity, measuring body composition with two bioelectrical impedance-based devices (TANITA and BIACORPUS). For a small patient group, additional data were collected with air displacement plethysmography (BOD POD) and dual-energy X-ray absorptiometry (DXA). (3) Results: Our combined data on 123 patients (age: 6–18 years, body mass index (BMI): 21–59 kg/m²) and the individual studies showed that TANITA and BIACORPUS yield significantly different results on body composition, TANITA overestimating body fat percentage and fat mass relative to BIACORPUS and underestimating fat-free mass (p < 0.001 for all three parameters). A Bland–Altman plot indicated little agreement between methods, which produce clinically relevant differences for all three parameters. We detected gender-specific differences with both methods, with body fat percentage being lower (p < 0.01) and fat-free mass higher (p < 0.001) in males than females. (4) Conclusions: Both bioelectrical impedance-based methods provide significantly different results on body composition in young patients with obesity and thus cannot be used interchangeably, requiring adherence to a specific device for repetitive measurements to ascertain comparability of data.

Even though a wide range of exercise recommendations exist for various patient groups, there is a lack of programmes, which are specifically designed for children and adolescents with obesity. This study is a secondary analysis of a trial, which evaluated the effectiveness of a physical intervention programme specifically designed for paediatric patients with obesity from a biomechanical and physical therapy point of view. It presents secondary results to body composition, nutrition and psychological status. The main investigation entitled "The Children's KNEEs study 1 " (ClinicalTrials.gov. ID#NCT02545764) was a randomised controlled trial evaluating the effects of a 12-week strength and neuromuscular exercise programme for the lower extremity on knee load, pain and function. Patients with obesity were recruited from

BackgroundThe determination of body composition is an important method to investigate obese patients and to evaluate the efficacy of medical interventions. Bioelectrical impedance-based methods are convenient, non-invasive and widely applied for this purpose, but need to be validated for their use in young obese patients.MethodsWe compiled data from three independent studies on different aspects of obesity in children and adolescents, measuring body composition with two bioelectrical impedance-based devices (TANITA and BIA). Further, for a small patient group additional data were collected with air displacement plethysmography (BOD POD) and DXA.ResultsBoth, the combined data of the entire study population of 123 patients (age: 6-18 years, BMI: 21-59 kg/m²) and the data of each individual study, showed that TANITA and BIA yield significantly different results on body composition, with TANITA overestimating body fat percentage and fat mass relative to BIA and underestimating fat-free mass (p < 0.001 for all three parameters). A Bland-Altman plot revealed that both methods show little agreement and produce clinically relevant differences for all three parameters. In addition, we detected gender-specific differences with both methods, body fat percentage being significantly lower (p < 0.01) and fat-free mass significantly higher (p < 0.001) in males than females. A comparison of bioelectrical impedance-based methods with BOD POD and DXA on a small patient group indicated no significant difference between methods.ConclusionsBoth bioelectrical impedance-based methods provide significantly different results on body composition in young obese patients and the data thus cannot be used interchangeably. Routine clinical practice may nonetheless use these devices but must adhere to a specific device for repetitive measurements to ascertain comparability of data.Trial registration: Study#2, Children`s KNEEs study, ClinicalTrials NCT02545764. Registered 10 September 2015, https://clinicaltrials.gov/ct2/show/results/NCT02545764