Avaliação da técnica de impedância bioelétrica na identificação das alterações da composição corporal em mulheres no período pós-parto

Abstract

The aim of the present study is to assure that the measurement of the bioelectrical impedance (IB) identifies the changes in the body composition of postpartum women. Forty-seven women (≥ 18 years of age) were enrolled in the study. Body composition (BC) - fat free mass (FFM), fat mass (FM) and percentage body fat (%BF) - was obtained by two IB devices (Tanita BC 533 and RJL 101) and DXA. All measurements were performed at the same day in two different postpartum moments. The women were categorized in two groups: with weight loss (WWL, n= 24) and with weight gain (WWG, n= 22). Pair T-test was used to compare mean difference values within methods and DXA. Bland & Altman plots and intraclass correlation coefficients (ICC) were used to evaluate the agreement between body composition changes obtained by both IB and DXA. The first and second visits for BC measurements occurred 2,6 ± 2,0 months e 8,0 ± 2,7 months after delivery, respectively. Mean (± SD) age was 26.7 ± 5.2 years and body mass was 74.6 ± 11.4 kg at the first visit and 75.1 ± 12.6 kg at the second visit. Women were overweight in both visits (BMI= 28.8 ± 4,0kg/m2 e 29.0 ± 4.6 kg/m2). % BF measured by DXA at the first visit was 40.1 ± 4.9% and at the second visit was 41.0 ± 5.2% yielding on average a FM of 30.2 ± 6,6 kg and 30,9 ± 8,0 kg, respectively.. IB_Tantia yelded lower mean values for FFM and FM compare to DXA mean values, except for %BF. Both IB underestimated %BF (-0.7% for Tanita and -1.1% for RJL) and FM changes (-0.6 kg for Tanita and -1.0 for RJL) compared to DXA changes. On the other hand FFM changes were overestimated by Tanita (0,8 kg) and RJL (1,0 kg). There was a good agreement (CCI ≥ 0.75) between FM changes measured by IB_Tanita and DXA and a fair agreement for IB_RJL. Therefore the IB technique was able to identified FM changes, and IB_Tanita showed a better performance than IB_RJL on the estimation of FM changes in these postpartum women.