#4979 MORTALITY AND BIOIMPEDANCE SPECTROSCOPY–BASED DRY WEIGHT MEASUREMENT ERROR IN ELDERLY PATIENTS UNDERGOING HEMODIALYSIS

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Abstract Background and Aims Dry weight (DW) estimation is important for patients undergoing hemodialysis. Although bioimpedance spectroscopy (BIS) is often employed to evaluate DW, BIS-based DW frequently differs from clinical DW. In this study, the characteristics of elderly patients were evaluated by separating them into groups based on the degree of disparity between the BIS-based DW and the clinically appropriate (DWGAP), and the mortality of each group was compared. Method This retrospective study included patients who underwent hemodialysis at Chungnam National University Hospital from January 1, 2016, to June 2020. All patients were aged ≥60 years. Patients with cancer, recipients of kidney transplant, and patients who dropped out of the study within 3 years were excluded. Body composition was assessed using a portable BIS device (Fresenius Medical Care, Bad Homburg, Germany). The BIS dataset includes extracellular water (ECW), intracellular water (ICW), and total body water level (TBW) as well as the lean tissue index (LTI), fat mass index (FTI), ECW/ICW ratio (E/I), lean tissue mass, fat mass (FAT), adipose tissue mass (ATM), and body cell mass (BCM). The absolute value of the gap between the BIS-based DW and the actual clinically appropriate dry weight was determined (DWGAP). To assess differences in blood chemistry and survival rate, four groups were classified based on the absolute value of DWGAP; Group 1: DWGAP < 0.5 kg, Group 2: 0.5 kg ≤ DWGAP < 1 kg, Group 3: 1 kg ≤ DWGAP < 2 kg, and Group 4: 2 kg < DWGAP. The mortality data of patients up to 3 years after BIS measurement were collected. Results There were 1024 patients in all. The study excluded 29 individuals with cancer, 31 patients with KT, and 249 participants with a loss of follow-up before 36 months. A total of 715 patients were analyzed: Group 1 (n = 236), Group 2 (n = 171), Group 3 (n = 137), and Group 4 (n = 171). The mean age for each group was 71.97, 70.73, 71.58, and 70.4 years, respectively. Groups 1 and 2 had the same survival rates (78%); however, Group 3 had a lower rate (73%) and Group 4 showed a significant decline (59%). In the laboratory test, Group 4 had lower hemoglobin, total protein, albumin, creatinine, and chloride levels than Groups 1, 2, and 3. In the BIS data, ECW and E/I were higher in Group 4 than in Groups 1, 2, and 3. Conclusion In the elderly patient group, mortality increased in the group where the DWGAP was >2 kg. Lower blood albumin levels, total protein levels, and E/I ratios of ≥1 were detected in the group with a gap of ≥2 kg, and these parameters are likely to adversely affect the survival of elderly patients requiring dialysis.