The Impact of Volume Overload on the Longitudinal Change of Adipose and Lean Tissue Mass in Incident Chinese Peritoneal Dialysis Patients

Association of changes in body composition with all-cause mortality in patients undergoing hemodialysis: A prospective cohort study

OBJECTIVES

This study aimed to explore the effect of longitudinal body composition changes on mortality risk in patients undergoing hemodialysis and identify whether changes in body composition can more accurately predict mortality than baseline status.

METHODS

A prospective cohort study was conducted on 340 patients undergoing hemodialysis. Lean mass and body fat were determined using a bioimpedance spectroscopy (BIS) device and expressed as the lean tissue index (LTI) or fat tissue index (FTI), respectively. The patients were subjected to BIS at baseline and after 1 year. The hazard ratio (HR) for death was calculated using Cox regression analysis.

RESULTS

Among 340 patients, 289 were tested with a repeat BIS. LTI loss and FTI gain were observed in 51.2% and 47.1% of the patients, respectively. Low baseline LTI was a significant predictor of all-cause mortality after adjusting for demographic and biochemical parameters (HR, 2.41; P = 0.047), but not when comorbidities were included in the multivariate analysis. However, after adjusting for various confounding factors, LTI loss (HR, 3.40; P = 0.039) and FTI gain (HR, 4.06; P = 0.024) were independent risk factors for all-cause mortality, and the adjusted HR for LTI loss and FTI gain vs. no LTI loss and no FTI gain was 5.34 (P = 0.016).

CONCLUSIONS

LTI loss and FTI gain, particularly their combination, are important predictors of survival in patients undergoing hemodialysis. Our results emphasize that longitudinal changes in LTI and FTI are more strongly associated with all-cause mortality than single-point values. Therefore, it is important to dynamically assess the muscle and fat tissues and develop potential targeted treatment strategies for this population.

Comparing bioimpedance spectrometry and traditional creatinine kinetics methods for the assessment of muscle mass in peritoneal dialysis patients

Background

Sarcopenia is a common and serious problem in patients receiving peritoneal dialysis (PD). Lean tissue mass (LTM) by bioimpedance spectrometry is a reasonably accurate method for measuring muscle mass. Fat-free edema-free body mass (FEBM) as determined by the creatinine kinetics method is a traditional method but evidence to support its use is limited.

Methods

We studied 198 new PD patients. Their serial LTM and FEBM were reviewed and compared by the Bland and Altman method. Multi-variable regression model was used to determine factors associated with the disparity between the two methods.

Results

There was a significant but moderate correlation between LTM and FEBM (r = 0.309, P < .0001). LTM was consistently higher than FEBM, with an average difference 13.98 kg (95% confidence interval -5.90 to 33.86 kg), and the difference strongly correlated with LTM (r = 0.781, P < .0001). By multivariable linear regression analysis, LTM and residual renal function were independent predictors of the LTM-FEBM difference. Where the measurements were repeated in 12 months, there was no significant correlation between ∆LTM and ∆FEBM (r = -0.031, P = .799).

Conclusion

There is a significant difference between LTM and FFBM. This discrepancy correlated with LTM and residual renal function, highlighting the limitations of FFBM in assessing skeletal muscle mass.

Frailty in patients on dialysis

Frailty is a condition that is frequently observed among patients undergoing dialysis. Frailty is characterized by a decline in both physiological state and cognitive state, leading to a combination of symptoms, such as weight loss, exhaustion, low physical activity level, weakness, and slow walking speed. Frail patients not only experience a poor quality of life, but also are at higher risk of hospitalization, infection, cardiovascular events, dialysis-associated complications, and death. Frailty occurs as a result of a combination and interaction of various medical issues in patients who are on dialysis. Unfortunately, frailty has no cure. To address frailty, a multifaceted approach is necessary, involving coordinated efforts from nephrologists, geriatricians, nurses, allied health practitioners, and family members. Strategies such as optimizing nutrition and chronic kidney disease-related complications, reducing polypharmacy by deprescription, personalizing dialysis prescription, and considering home-based or assisted dialysis may help slow the decline of physical function over time in subjects with frailty. This review discusses the underlying causes of frailty in patients on dialysis and examines the methods and difficulties involved in managing frailty among this group.

Nutritional Assessments by Bioimpedance Technique in Dialysis Patients

Bioelectrical impedance analysis (BIA) has been extensively applied in nutritional assessments on the general population, and it is recommended in establishing the diagnosis of malnutrition and sarcopenia. The bioimpedance technique has become a promising modality through which to measure the whole-body composition in dialysis patients, where the presence of subclinical volume overload and sarcopenic obesity may be overlooked by assessing body weight alone. In the past two decades, bioimpedance devices have evolved from applying a single frequency to a range of frequencies (bioimpedance spectroscopy, BIS), in which the latter is incorporated with a three-compartment model that allows for the simultaneous measurement of the volume of overhydration, adipose tissue mass (ATM), and lean tissue mass (LTM). However, clinicians should be aware of common potential limitations, such as the adoption of population-specific prediction equations in some BIA devices. Inherent prediction error does exist in the bioimpedance technique, but the extent to which this error becomes clinically significant remains to be determined. Importantly, reduction in LTM has been associated with increased risk of frailty, hospitalization, and mortality in dialysis patients, whereas the prognostic value of ATM remains debatable. Further studies are needed to determine whether modifications of bioimpedance-derived body composition parameters through nutrition intervention can result in clinical benefits.

Weight loss and weight gains in patients starting peritoneal dialysis; the effect of peritonitis

AIM

Earlier studies reported that peritoneal dialysis (PD) patients gained fat mass after initiating dialysis. Clinical practice and demographics have changed over time with earlier initiation of dialysis and increasing numbers of elderly, co-morbid patients. As such, we wished to review changes in body composition with dialysis.

METHODS

Changes in body composition were compared by dual x-ray absorptiometry (DXA) in 151 adult PD patients, 81 males (54.6%), 50 diabetic (30.1%), mean age 60.5 ± 16.7 years, shortly after starting PD and then a median of 24 months later, to allow for the initial impact of dialysis.

RESULTS

Overall, weight appeared stable (71.7 ± 15.4 vs. 71.9 ± 15.3 kg). On follow-up, total weekly urea clearance fell from 2.29 (1.85-3.0) to 1.93 (1.63-2.4) whereas peritoneal glucose absorption increased from 119 (46-217) to 321 (187-805) mmol/day, p < .001, and estimated dietary protein (nPNA) fell from 0.92 ± 0.23 to 0.86 ± 0.23 g/kg/day, p = .006. However, 69 (45.7%) patients gained weight, with greater change in both lean and fat mass index versus those with weight loss (0.8 [-0.5 to 2.0] vs. -0.7 [-2.1 to 0.2] and 0.9 [-0.1 to 2.3] vs. 0 [-2.6 to 0.8] kg/m² , p < .001), respectively. Although there were no differences in hospital admissions, patients who gained weight experienced fewer episodes of PD peritonitis (0 [0-1] vs. 1[0-2], p = .019).

CONCLUSION

Dietary protein intake declined over time, and more PD patients lost weight. The major difference between those who gained and lost weight was episodes of peritonitis. Greater attention to nutritional support may potentially reduce loss of lean body mass.

Nutritional Assessment and Nutrient Supplement in Patients with Chronic Kidney Disease

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