Risk stratification for patients awaiting kidney transplantation: Role of bioimpedance derived edema index and nutrition status

Abstract

Background: Recent studies demonstrate that the edema index (ECW/TBW) may be a significant predictor of poor outcomes as a composite of overhydration and protein-energy wasting. There is no consensus regarding ECW/TBW cut-off values. We aimed to determine the performance of ECW/TBW in all-cause mortality prediction and to establish certain cut-off values in patients on chronic hemodialysis.

Methods: Body composition of 158 hemodialysis patient was performed by using InBody S10 (Biospace, Seoul, Korea) analyzer. Demographic profile and laboratory data were collected. Subjective Global Assessment Scale (SGA) was used to assess nutrition status. In the mean follow up of 3.5 ± 1.15 years, two independent clinicians evaluated death cases and factors for all-cause mortality were established. Statistical analysis was performed with R software.

Results: 73 of 158 hemodialysis patients were on kidney transplant waiting list. Mean age of study subjects was 53.6 ± 15.1 years, 51.9% were females, and 13.9% had diabetes. During the follow-up period, 17.72% of patients died. They had significantly higher ECW/TBW values 0.393 vs 0.408, p < 0.001. Subjects with lower edema index had better nutrition according to SGA (SGA A 0.391; SGA B 0.400; SGA C 0.413; p < 0.001). The calculated ECW/TBW cut-off point for all-cause mortality was 0.4055, with sensitivity of 84.6%, specificity of 69.8%. On the other hand, the cut-off point for SGA scores B and C was 0.396 with sensitivity of 72.7% and specificity of 68.7%.

Conclusion: The manufacturer provided ECW/TBW cut-off point of 0.400 should be addressed carefully, because it varies depending on the selected outcome and population studied. InBody ECW/TBW reference values from 0.390 to 0.410 are the most promising in hemodialysis population to assess all-cause mortality, nutrition status and body composition.

Keywords: Bioelectrical impedance analysis; Fluid overload; Hemodialysis; Malnutrition.