Reliability of bioelectrical impedance analysis in the evaluation of the nutritional status of hemodialysis patients

Uremic malnutrition, also known as protein-energy wasting (PEW), is a common phenomenon in maintenance hemodialysis (MHD) patients in transplantation waiting list and a risk factor for poor clinical outcomes including worse quality of life and increased hospitalization and mortality. The three major causes of PEW in MHD patients are low nutrient intake, comorbid conditions and the dialysis procedure itself. Bioelectrical impedance analysis (BIA) is an optimal, comprehensive, inexpensive, noninvasive system that assesses body composition, and is a useful measure of clinical status of MHD patients. In this present study, we compared diagnostic ability of mini nutritional assessment (MNA) and BIA in 100 transplantation waiting MHD patients. To validate reliability of BIA in MHD patients, we analyzed MNA scores, biochemical nutritional markers and BIA findings in 100 patients (62 male, age 54.3±13.1). Anthropometric and body composition analyses were performed for all patients. Body compositions were analyzed by using the Body Composition Analyzer (Tanita BC- 420MA). Monthly assessed biochemical parameters including albumin, CRP, lipid profile and creatinin of the last 6 months were respectively collected. Patients were grouped according to MNA scores as well-nourished (n:36, score≥24), moderate PEW or risk group (n:49, score 17-23.5) and PEW group(n:15, score<17). Biochemical and BIA findings of these groups were compared. Patient groups were similar in means of demographic characteristis. Mean duration of being under MHD treatment was significantly lower in PEW group compared to both other groups (p:0.015). Well-nourished and risk groups had lower CRP and higher albumin levels compared to PEW patients, however these values were statistically similar in these two groups (p:0.018, 0.01 respectively). Creatinine levels were highest in well-nourished group and also moderate PEW /risk group had higher creatinine levels compared to PEW group (p: 0.004). According to BIA findings we observed that well-nourished patients had highest fat ratio, fat mass, muscle mass, visceral fat mass and fat free mass compared to both moderate PEW/risk group and PEW group. Risk group patients also had higher muscle mass, visceral fat mass and fat free mass values compared to PEW group. A correlation analysis revealed that MNA scores were positively correlated with albumin (r:0.279, p:0.005), creatinine (r:0.197, p:0.049), fat mass (r: 0.201, p:0.045), muscle mass (r:0.382, p:0.001), visceral fat ratio (r: 0.270, p:0.007) and BMI (r:0.199, p:0.047) and in negative correlation with CRP (r:-0.357, p:0.0001) levels. Our results indicate that MNA and BİA are clinically adequate and positively correlated methods for assessing nutritional status in MHD patients. Being an inexpensive and practical method we recommend BİA as a useful diagnostic tool for early diagnosis and follow-up of PEW in MHD patients.