Título

COMPARISON BETWEEN DUAL-ENERGY X-RAY ABSORPTIOMETRY AND BIOELECTRICAL IMPEDANCE FOR BODY COMPOSITION MEASUREMENTS IN ADULTS WITH CHRONIC KIDNEY DISEASE: A CROSS-SECTIONAL, LONGITUDINAL AND MULTI-TREATMENT ANALYSIS.

Resumo

Chronic kidney disease (CKD) patients frequently present a compromised nutritional status. Due to limited availability of reference methods to assess nutritional status, alternative methods are used. We aimed to evaluate the agreement between bioelectrical impedance spectroscopy (BIS) and Dual-energy X-ray Absorptiometry (DXA) for assessment of body composition in CKD. Cross-sectional and prospective analyses by DXA and BIS in whole-body (BISWB) and segmental (BISSEG) protocols were performed in CKD non-dialysis-dependent (n=81), hemodialysis (n=83), peritoneal dialysis (n=24), and renal transplantation (n=80) patients. Intraclass correlation coefficient (ICC) and Bland-Altman plots were evaluated; linear regression analysis was performed for bias assessment and development of equations; ROC curve was constructed for diagnosis of inadequate error tolerance (DXA - BIS > ± 2 kg). A total of 266 patients were included, being 137 men and 129 women. Total sample had a mean age of 47 ± 10 years old. CKD was secondary to systemic arterial hypertension in 29% of the total sample, to glomerulonephritis in 25% and to diabetes mellitus in 10%. The agreement with DXA was greater for BISWB than BISSEG; for fat mass (FM) (ICC in men = 0.894; ICC in women = 0.931) than fat free mass (FFM) (ICC in men = 0.566; ICC in women = 0.525), with greater bias for FFM as muscle increases and for FM in body fat extremes. The agreement was lower for body change analysis (prospective - cross sectional data) (FFM, ICC in men = 0.196; ICC in women = 0.495; FM, ICC in men = 0.465; ICC in women = 0.582). Extra to intracellular water ratio (ECW/ICW), body mass index, fat mass index, waist circumference, resistance, and reactance interfered in bias between methods. FFM had poorer agreement in the last tertile of ECW/ICW sample (ICC in men = 0.69, 0.68 and 0.51; ICC in women = 0.71, 0.74 and 0.38 for first, second and third tertiles, respectively). An ECW/ICW cut-off point of >0.725 for inadequate error tolerance was determined. New prediction equations for FFM (r2 = 0.91) and FM (r2 = 0.88) presented adequate error tolerance in 55% and 63% compared to 30% and 39% of the original equation, respectively. So, for body composition evaluation in CKD, BIS applied using the whole-body protocol, in normal hydration CKD patients is as reliable as DXA; BIS must be used with caution among over-hydration patients with ECW/ICW > 0.725. The newly developed equations are indicated for greater precision.

Área

Nutrição

Autores

NATÁLIA TOMBORELLI BELLAFRONTE, Natália Tomborelli Bellafronte, Luisa Maria Diani, Lorena Vega-Piris, Paula Garcia Chiarello, Guillermina Barril Cuadrado