Sources of variation in estimates of lean body mass by creatinine kinetics and by methods based on body water or body mass index in patients on continuous peritoneal dialysis

Advanced wasting in peritoneal dialysis patients

AIM

To identify patients with end-stage renal disease treated by peritoneal dialysis (PD) who had zero body fat (BF) as determined by analysis of body composition using anthropometric formulas estimating body water (V) and to compare nutritional parameters between these patients and PD patients whose BF was above zero.

METHODS

Body weight (W) consists of fat-free mass (FFM) and BF. Anthropometric formulas for calculating V allow the calculation of FFM as V/0.73, where 0.73 is the water fraction of FFM at normal hydration. Wasting from loss of BF has adverse survival outcomes in PD. Advanced wasting was defined as zero BF when V/0.73 is equal to or exceeds W. This study, which analyzed 439 PD patients at their first clearance study, used the Watson formulas estimating V to identify patients with V_Watson/0.73 ≥ W and compared their nutritional indices with those of PD patients with V_Watson/0.73 < W.

RESULTS

The study identified at the first clearance study two male patients with V_Watson/0.73 ≥ W among 439 patients on PD. Compared to 260 other male patients on PD, the two subjects with advanced wasting had exceptionally low body mass index and serum albumin concentration. The first of the two subjects also had very low values for serum creatinine concentration and total (in urine and spent peritoneal dialysate) creatinine excretion rate while the second subject had an elevated serum creatinine concentration and high creatinine excretion rate due, most probably, to non-compliance with the PD prescription.

CONCLUSION

Advanced wasting (zero BF) in PD patients, identified by the anthropometric formulas that estimate V, while rare, is associated with indices of poor somatic and visceral nutrition.

Functional impairment is associated with an increased risk of mortality in patients on chronic hemodialysis

BACKGROUND

Functional impairment is associated with adverse outcomes in older people, as well as in patients on chronic hemodialysis. The aim of the present study was to determine the characteristics associated with functional impairment in chronic hemodialysis, and to evaluate if functional impairment represents a risk factor for reduced survival in chronic hemodialysis.

METHODS

All 132 chronic hemodialysis referring to the Hemodialysis Service of the Catholic University, Rome, Italy between November 2007 and May 2015 were included. All patients underwent comprehensive geriatric assessment; functional ability was estimated using two questionnaires exploring independency in bathing, dressing, toileting, transferring, continence, feeding (ADLs), and independency in using the telephone, shopping, food preparation, housekeeping, laundering, traveling, taking medications, and handling finances (IADLs). Functional impairment was diagnosed in presence of dependence in one or more ADLs/IADLs. Mood was assessed using the 30-item Geriatric Depression Scale. Logistic regression was used to evaluate factors associated with functional impairment. The association between functional impairment and survival was assessed by Cox regression.

RESULTS

ADLs impairment was present in 34 (26 %) participants, while IADLs impairment was detected in 64 (48 %) subjects. After a follow up of 90 months, 55 (42 %) patients died. In logistic regression, depressive symptoms were associated with ADLs and IADLs impairment (OR 1.12; 95 % CI = 1.02-1.23; OR 1.16; 95 % CI = 1.02-1.33; respectively). In Cox regression, ADLs impairment was associated with mortality (HR 2.47; 95 % CI-1.07-5.67) while IADLs impairment was not associated with reduced survival (HR .80; 95 % CI-.36-1.76).

CONCLUSIONS

Functional impairment is associated with depressive symptoms; also, impairment in the ADLs represents a risk factor of reduced survival in chronic hemodialysis. These associations and their potential implication should be assessed in dedicated studies.

Factors Associated with the Serum Myostatin Level in Patients Undergoing Peritoneal Dialysis: Potential Effects of Skeletal Muscle Mass and Vitamin D Receptor Activator Use

Myostatin is a member of the transforming growth factor-β family, which regulates synthesis and degradation of skeletal muscle proteins and is associated with the development of sarcopenia. It is up-regulated in the skeletal muscle of chronic kidney disease patients and is considered to be involved in the development of uremic sarcopenia. However, serum myostatin levels have rarely been determined, and the relationship between serum myostatin levels with clinical and metabolic factors remains unknown. This cross-sectional study investigated the association between serum myostatin level and clinical factors in 69 outpatients undergoing peritoneal dialysis. Serum myostatin level was determined by commercially available enzyme-linked immunosorbent assay (ELISA). Univariable and multivariable analysis were conducted to determine factors associated with serum myostatin levels. The factors included age, sex, diabetes mellitus, dialysis history, body mass index, residual kidney function, peritoneal dialysate volume, serum biochemistries, and the use of vitamin D receptor activators (VDRAs). Mean serum myostatin level was 7.59 ± 3.37 ng/mL. There was no association between serum myostatin level and residual kidney function. Serum myostatin levels were significantly and positively associated with lean body mass measured by the creatinine kinetic method and negatively associated with the use of VDRAs after adjustment for potential confounding factors. Our study indicated that serum myostatin levels are associated with skeletal muscle mass and are lower in patients treated with VDRAs. Further studies are necessary to determine the significance of measuring serum myostatin level in patients undergoing peritoneal dialysis.

Lean body mass predicts long-term survival in Chinese patients on peritoneal dialysis

Background

Reduced lean body mass (LBM) is one of the main indicators in malnutrition inflammation syndrome among patients on dialysis. However, the influence of LBM on peritoneal dialysis (PD) patients’ outcomes and the factors related to increasing LBM are seldom reported.

Methods

We enrolled 103 incident PD patients between 2002 and 2003, and followed them until December 2011. Clinical characteristics, PD-associated parameters, residual renal function, and serum chemistry profiles of each patient were collected at 1 month and 1 year after initiating PD. LBM was estimated using creatinine index corrected with body weight. Multiple linear regression analysis, Kaplan–Meier survival analysis, and Cox regression proportional hazard analysis were used to define independent variables and compare survival between groups.

Results

Using the median LBM value (70% for men and 64% for women), patients were divided into group 1 (n = 52; low LBM) and group 2 (n = 51; high LBM). Group 1 patients had higher rates of peritonitis (1.6 vs. 1.1/100 patient months; p<0.05) and hospitalization (14.6 vs. 9.7/100 patient months; p<0.05). Group 1 patients also had shorter overall survival and technique survival (p<0.01). Each percentage point increase in LBM reduced the hazard ratio for mortality by 8% after adjustment for diabetes, age, sex, and body mass index (BMI). Changes in residual renal function and protein catabolic rate were independently associated with changes in LBM in the first year of PD.

Conclusions

LBM serves as a good parameter in addition to BMI to predict the survival of patients on PD. Preserving residual renal function and increasing protein intake can increase LBM.

Waist-to-Hip Ratio, Cardiovascular Outcomes, and Death in Peritoneal Dialysis Patients

Objectives. The primary objective of this study was to determine the relationship between waist-to-hip ratio (WHR), cardiovascular (CV) events, and mortality in peritoneal dialysis (PD) patients. A secondary objective was to investigate the association between abdominal obesity and systemic inflammatory markers. Methods. This is a prospective study of 22 prevalent PD patients. WHR was measured at baseline. C-reactive protein (CRP), tumour necrosis factor-α (TNF-α), and interleukin-6 (IL-6) were measured. Main outcomes were first CV event and death from all causes. Survival analysis was used to examine the relationship between anthropomorphic measures and clinical outcomes. Results. Mean follow-up period was 3.1 years. In Kaplan-Meier analysis, survival was lower in those with higher WHR (P = .002). In Cox regression, WHR independently predicted mortality and first CV event after adjustment for known ischemic heart disease (hazard ratio [HR] 1.17, confidence interval [CI] 1.05-1.30 for death; HR 1.13, CI 1.01-1.26 for CV event). WHR correlated with serum TNF-α (r = 0.45; P = .05). Conclusion. The results of this study suggest WHR may be a risk factor for increased CV events and mortality in PD patients. Abdominal obesity is also associated with inflammatory markers. Larger studies are warranted to confirm these findings.