Nutritional status and overhydration: can bioimpedance spectroscopy be useful in haemodialysis patients?

Background: Protein-energy wasting (PEW), associated with inflammation and overhydration, is common in haemodialysis (HD) patients and is associated with high morbidity and mortality. Objective: Assess the relationship between nutritional status, markers of inflammation and body composition through bioimpedance spectroscopy (BIS) in HD patients. Methods: This observational, cross-sectional, single centre study, carried out in an HD centre in Forte da Casa (Portugal), involved 75 patients on an HD programme. In all participating patients, the following laboratory tests were conducted: haemoglobin, albumin, C-reactive protein (CRP) and 25-hydroxyvitamin D3 [25(OH)D3]. The body mass index of all patients was calculated and a modified version of subjective global assessment (SGA) was produced for patients on dialysis. Intracellular water (ICW) and extracellular water (ECVO were measured by BIS (Body Composition Monitor(R), Fresenius Medical Care) after the HD session. In statistical analysis, Spearman's correlation was used for the univariate analysis and linear regression for the multivariate analysis (SPSS 14.0). A P value of <.05 was considered statistically significant. Results: PEW, inversely assessed through the ICW/body weight (BIM ratio, was positively related to age (p<.001), presence of diabetes (p=.0041 BMI (p=.01) and CRP (P=.008) and negatively related to albumin (p=.006) and 25(OH)D3 (p=.007). Overhydration, assessed directly through the ECW/BW ratio, was positively related with CRP (p=.009) and SGA (p=.03), and negatively with 25(OH)D3 (p=.006) and BMI (p=.01). In multivariate analysis, PEW was associated with older age (p<001), the presence of diabetes (p=.003), lower 25(OH)D3 (p=.008), higher CRP (p=.001) and lower albumin levels (p=.004). Overhydration was associated with higher CRP (p=.001) and lower levels of 25(OH)D3 (p=.003). Conclusions: Taking these results into account, the ICW/BW and ECW/BW ratios, assessed with BIS, have proven to be good markers of the nutritional and inflammatory status of HD patients. BIS may be a useful tool for regularly assessing the nutritional and hydration status in these patients and may allow nutritional advice to be improved and adjusted.