The impact of plantar callosities, arm posture, and use of electrolyte wipes on the reliability of body composition measurements by BIA in morbidly obese adults
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Objective: The purpose of this study was to evaluate the reliability and validity of body composition measurements in morbidly obese adults. These measurements were obtained using multiple-frequency bioelectrical impedance analysis (BIA) under different conditions: pre and post pedicure for removal of callosities, with and without InBody electrolyte wipes and custom-built axillary pads. For validity purposes, body composition measurements from BIA were compared with measurements from air displacement plethysmography (ADP). Design: Repeated measures, clinical intervention study testing the reliability and validity of BIA in the morbidly obese. Subjects: 36 morbidly obese patients from St. Olav University Hospital (13 males, 23 females, aged 28-70, BMI 41.6 ± SD 4.3) with moderate to severe callosities. Measurements: Body composition was assessed as percentage of body fat (%BF) using ADP and multiple-frequency BIA. Body weight and height measurements were also taken; plantar callosities were photographed and scored for severity using a 5-point scale by an authorized podiatrist. BIA measurements were taken before and after removal of plantar callosities (pedicure), and with or without InBody electrolyte wipes and custombuilt axillary pads. Results: The study participants’ %BF measurements were found to be significantly higher with axillary pads than without (p < .001). No statistically significant differences were found in %BF measurements pre to post pedicure, and with vs. without usage of electrolyte wipes. There were also no statistically significant differences in %BF between BIA and ADP. Conclusion: Multiple-frequency BIA is a valid method for estimating %BF in morbidly obese adults. Arm posture appears to have a significant impact on %BF assessed by BIA, as opposed to the presence of plantar callosities and usage of InBody electrolyte wipes, which showed no significant effect. Further examination of the effect of skin contact between the arm and trunk on the accuracy of BIA measurements is warranted. For clinical and scientific purposes, standardization of BIA measurement procedures is recommended.