Prognostic value of single-measure of body composition analysis parameters in hospitalized uremic patients undergoing dialysis

Abstract

Objective To explore the predictive value of single-measured nutritional and fluid load parameters by bioelectrical impedance in the prognosis of hospitalized uremic patients undergoing dialysis. Methods Adult uremic patients undergoing maintenance dialysis (including hemodialysis and peritoneal dialysis) were recruited prospectively and continuously from the Department of Nephrology, the First Affiliated Hospital of Nanjing Medical University from January 2014 to December 2016. The body composition was measured by bioelectrical impedance method before dialysis within 3 days after admission. Kaplan-Meier method was used to plot survival curves. Cox regression analysis was used to analyze the relationship between prognosis and the following body composition analysis parameters: lean tissue index (LTI), fat tissue index (FTI), the ratio of extracellular water (ECW) to body cell mass (BCM), and over hydration (OH). The multivariate-correcting Cox regression analysis was also performed. Results (1) A total of 819 patients were enrolled including 696 hemodialysis patients and 123 peritoneal dialysis patients after excluding 12 patients of loss to follow-up and 20 patients who underwent renal transplantation during the follow-up period. The mean follow-up time was 28.1±9.7 months while 172 (21%) patients died in the duration of follow-up. (2)The patients were divided into three groups according to OH 1 L, into fluid overload group and fluid balance group according to the OH/ECW ratio, and into 4 groups according to the quartiles of LTI, FTI or ECM/BCM. Survival analysis found no significant difference in death between patients in different OH groups (χ2=2.4767, P=0.2899), while there were significant differences in death between the two groups of patients with different body fluid status (χ2=12.3874, P=0.0004), and among the different four groups of LTI (χ2=57.0897, P 35.2 and LTI>11.5 group, Alb>35.2 and LTI≤11.5 group, Alb≤35.2 and LTI>11.5 group, and Alb≤35.2 and LTI≤11.5 group. Interaction analysis showed that there was no interaction between blood Alb and LTI. (4) Subgroup analysis showed that the results of hemodialysis subgroup (n=696) were similar to those of the general population, while FTI and LTI of the peritoneal dialysis subgroup (n=123) had no significant relationship with the prognosis of patients. Conclusion Lower LTI, higher FTI, higher ECW/BCM, and fluid overload were significantly associated with midterm death of patients, while single-measure OH value had no significant correlation with the midterm death of dialysis patients. Even after adjusting for age and Charlson comorbidity score, the LTI was still independent of Alb and associated with prognosis, and there was no interaction between them, suggesting that LTI combined with serum Alb could be used for evaluating nutritional indicators and prognosis of uremic patients. Key words: Uremia; Body composition analysis; Nutrition; Liquid load; Lean Tissue Index