Comparative Performance of Body Composition Parameters in Prediction of Death in Hospitalized Patients on Maintenance Hemodialysis: A Cohort Study

Abstract

We compared the prognostic value of nutritional or volumetric parameters measured by body composition in hospitalized patients on maintenance hemodialysis. We conducted a cohort study to assess the association of different parameters of body composition with all-cause mortality in inpatients admitted to our nephrology department from January 2014 to December 2016. Of the 704 study patients, 160 (22.7%) died during a median follow-up of 33 months. In multivariate adjusted Cox models, higher ratio of extracellular water to body cell mass (ECW/BCM) (adjusted HR per 1-SD, 1.49; 95% CI, 1.19 to 1.85), lower lean tissue index (LTI) (adjusted HR per 1-SD, 0.70; 95% CI, 0.57 to 0.86) and lower body cell mass index (BCMI) (adjusted HR per 1-SD, 0.70; 95% CI, 0.58 to 0.85) were associated with a significantly greater risk of death. When these parameters were added to the fully adjusted model, BCMI performed best in improving the predictability for all-cause mortality (integrated discrimination improvement = 0.02, P = 0.04; net reclassification index = 0.11, P = 0.04). Among body composition indexes, ECW/BCM was the most relevant fluid volume indices to mortality and BCMI and LTI were the most relevant nutritional status indices to mortality in maintenance hemodialysis patients. End-stage renal disease (ESRD) has become one of the major health problems in the world. In 2010, it was estimated that 284 individuals per million population were undergoing maintenance dialysis throughout the world 1 , and the number of dialysis patients is growing at an alarming rate 2-5. Dialysis is the major treatment for ESRD and brings a heavy economic burden to all countries 6. Despite this, dialysis patients still have poor prognosis 5,7. The main risk factors for the mortality includes vascular access, cardiovascular complications, cerebrovascular complications, infection, anemia, mineral metabolic disorders, renal osteopathy, fluid overload (FO) and malnutrition 7,8. Bioelectrical impedance analysis-based body composition analysis is widely used and accepted as an ideal tool for assessing fluid volume and nutritional status in maintenance dialysis patients 9. It is easy-to-use, safe, noninvasive, repeatable and comprehensive. It has both anthropometric parameters in assessing fluid volume [such as overhydration (OH) 10 , OH/extracellular water (OH/ECW) 8,11-14 , the ratio of extracellular water to intracellular water (ECW/ICW) 15 , the ratio of extracellular water/body cell mass (ECW/BCM) 16,17 ] and nutrition status [such as lean tissue index (LTI) 11,18-23 , fat tissue index (FTI) 11,18 , body cell mass index (BCMI) 24,25 , BCM/weight 26 ]. However, it is still unclear which nutritional or volumetric parameters of body composition, measured by bioelectrical impedance, have the greatest prognostic value in maintenance hemodialysis patients. We designed this cohort study to assess and compare the association of different parameters in body composition with all-cause medium-term mortality in hemodialysis patients.

Increased extracellular water/body mass is associated with functional impairment in hemodialysis patients

“…Extracellular mass is mainly comprised of extracellular fluid. It has been suggested in previous studies that the ECW/BCM performed better than the OH/ECW as well as the ratio of ECW to intracellular water (ECW/ICW) in the assessment of fluid status [ 7 , 8 ]. Higher ECW/ICW ratios are associated with functional disability levels in patients with knee osteoarthritis [ 18 ].…”

“…Previous studies have suggested the ECW/BCM as a potential predictive factor for mortality risk in HD patients [ 6 ]. The ECW/BCM was found to perform better than overhydration and extracellular water (OH/ECW) in the assessment of fluid status in patients with acute kidney injury who required renal replacement therapy [ 7 ] as well as in those undergoing maintenance hemodialysis (MHD) [ 8 ]. Unfortunately, little is known about the relationship between the whole-body ECW/BCM ratio before dialysis and functional capabilities in MHD patients.…”

Estimation of Muscle Mass in the Integrated Assessment of Patients on Hemodialysis

“…With the 3C BIS method, estimation of body composition is based on a theoretical approach without the use of populationspecific regression equations. Lean tissue index (LTI), which corresponds to LTM, divided by height 2 , below the 10th percentile of a healthy age-matched reference population was independently related to outcome in most, but not all studies (8,15,37,38). Still, in a meta-analysis including over 15,000 patients, a low LTI was associated with increased mortality [Hazard ratio 1.53 (95% CI: 1.41-1.64)] (39).…”

Study on the Anthropometric and Body Composition Indices for Prediction of Cold and Heat Patter

“…Values of FFM, BFM, skeletal muscle mass (SMM), body cell mass (BCM), total body water (TBW), extracellular water (ECW) were extracted from the device. Fat-free mass index (FFMI), fat mass index (FMI) 16,17) , skeletal muscle index (SMI) 18) , body cell mass index (BCMI) 19,20) were calculated respectively as FFM, FM, SMM, and SCM divided by the squared height. ECW/TBW 21) is the ECW divided by TBW.…”