Energy Intake and Energy Expenditure Profiles in Peritoneal Dialysis Patients

Longitudinal association between dietary protein intake and survival in peritoneal dialysis patients

BACKGROUND

Decreased dietary protein intake (DPI) may lead to protein-energy malnutrition and may be associated with increased mortality risk. We hypothesized that longitudinal changes in dietary protein intake have independent associations with survival in peritoneal dialysis (PD) patients.

METHODS

668 stable PD patients were selected in the study from January 2006 to January 2018 and were followed up until December 2019. Their three-day dietary records were collected at the baseline (the sixth month after PD) and thereafter every 3 months for two and a half years. The latent class mixed models (LCMM) were used to identify subgroups of PD patients with similar longitudinal trajectories of DPI. The relation between DPI (baseline and longitudinal data) and survival was examined using Cox model to estimate death hazard ratios. Meanwhile, different formulae were used to assess nitrogen balance.

RESULTS

The results showed that baseline DPI ≤ 0.60g/kg/day was associated with the worst outcome in PD patients. Patients with DPI 0.80-0.99g/kg/day and DPI ≥ 1.0g/kg/day both presented positive nitrogen balance; patients with DPI 0.61-0.79g/kg/day presented obviously negative nitrogen balance. Longitudinal association between time-dependent DPI and survival was found in PD patients. The consistently low DPI' (0.61-0.79g/kg/d) group was correlated with increased death risk as compared with the 'consistently median DPI' group (0.80-0.99g/kg/d, HR = 1.59, p = 0.008), whereas there was no difference in survival between 'consistently median DPI' group and 'high-level DPI' group (≥1.0 g/kg/d, p > 0.05).

CONCLUSION

Our study revealed that DPI ≥ 0.8 g/kg/day was beneficial to the long-term outcome for the PD population.

Development and validation of a nomogram to predict protein-energy wasting in patients with peritoneal dialysis: a multicenter cohort study

Background

Protein-energy wasting (PEW) is a common complication in patients with peritoneal dialysis (PD). Few investigations involved risk factors identification and predictive model construction related to PEW. We aimed to develop a nomogram to predict PEW risk in patients with peritoneal dialysis.

Methods

We collected data from end-stage renal disease (ESRD) patients who regularly underwent peritoneal dialysis between January 2011 and November 2022 at two hospitals retrospectively. The outcome of the nomogram was PEW. Multivariate logistic regression screened predictors and established a nomogram. We measured the predictive performance based on discrimination ability, calibration, and clinical utility. Evaluation indicators were receiver operating characteristic (ROC), calibrate curve, and decision curve analysis (DCA). The performance calculation of the internal validation cohort validated the nomogram.

Results

In this study, 369 enrolled patients were divided into development (n = 210) and validation (n = 159) cohorts according to the proportion of 6:4. The incidence of PEW was 49.86%. Predictors were age, dialysis duration, glucose, C-reactive protein (CRP), creatinine clearance rate (Ccr), serum creatinine (Scr), serum calcium, and triglyceride (TG). These variables showed a good discriminate performance in development and validation cohorts (ROC = 0.769, 95% CI [0.705-0.832], ROC = 0.669, 95% CI [0.585-0.753]). This nomogram was adequately calibrated. The predicted probability was consistent with the observed outcome.

Conclusion

This nomogram can predict the risk of PEW in patients with PD and provide valuable evidence for PEW prevention and decision-making.

The brain and immune system prompt energy shortage in chronic inflammation and ageing

Sequelae frequently seen in patients with chronic inflammatory diseases, such as fatigue, depressed mood, sleep alterations, loss of appetite, muscle wasting, cachectic obesity, bone loss and hypertension, can be the result of energy shortages caused by an overactive immune system. These sequelae can also be found in patients with chronic inflammatory diseases that are in remission and in ageing individuals, despite the immune system being less active in these situations. This Perspectives article proposes a new way of understanding situations of chronic inflammation (such as rheumatic diseases) and ageing based on the principles of evolutionary medicine, energy regulation and neuroendocrine-immune crosstalk. A conceptual framework is provided to enable physicians and scientists to better understand the signs and symptoms of chronic inflammatory diseases and long-term disease consequences resulting from physical and mental inactivity.

Decrease in irisin in patients with chronic kidney disease

Patients with chronic kidney disease have abnormal energy expenditure and metabolism. The mechanisms underlying altered energy expenditure in uremia are unknown and remain to be elucidated. Irisin is a peroxisome proliferator-activated receptor γ coactivator 1-α–dependent myokine, and it increases energy expenditure in the absence of changes in food intake or activity. We hypothesize that chronic kidney disease patients have altered irisin levels. We measured resting irisin levels in 38 patients with stage 5 chronic kidney disease and in 19 age- and sex-matched normal subjects. Plasma irisin levels were significantly decreased in chronic kidney disease patients (58.59%; 95% CI 47.9%–69.2%, p<0.0001). The decrease in irisin levels was inversely correlated with the levels of blood urea nitrogen and creatinine. Further association analysis revealed that irisin level is independently associated with high-density lipoprotein cholesterol level. Our results suggest that chronic kidney disease patients have lower than normal irisin levels at rest. Furthermore, irisin may play a major role in affecting high-density lipoprotein cholesterol levels and abnormal energy expenditure in chronic kidney disease patients.

Does peritoneal dialysate affect body composition assessments using multi-frequency bioimpedance in peritoneal dialysis patients?

BACKGROUND/OBJECTIVES

Multi-frequency bioelectrical impedance analysis (MFBIA) is increasingly being used to assess peritoneal dialysis patients. Protein energy wasting (PEW) is a recognised complication of peritoneal dialysis. Although MFBIA can be used to assess body composition, measurements can be affected by fluid overload, and we wished to determine whether the presence of peritoneal dialysate in the peritoneal cavity equally could affect MFBIA-derived body composition assessments.

SUBJECTS/METHODS

Fifty consecutive adult patients had MFBIA made with 2l 22.7 g/l dextrose dialysate instilled into the peritoneal cavity and then after draining out.

RESULTS

When full, extracellular water (ECW) and the ratio of ECW to total body water (TBW) were greater compared with when empty: 13.9 ± 3.0l versus 13.4 ± 3.0, and 0.393 ± 0.01 versus 0.391 ± 0.01, P<0.001, respectively. Segmental ECW/TBW was only different for the trunk, 0.395 ± 0.01 full versus 0.392 ± 0.01 empty, P<0.0001. Body composition changed with a fall in skeletal muscle mass from 26.1 ± 6.3 to 25.2 ± 6.1 kg, P<0.001, and a smaller reduction in body fat from 19.3 ± 8.4 to 19.1 ± 8.0 kg, P=0.0104.

CONCLUSION

MFBIA measurements made in peritoneal dialysis patients with peritoneal dialysate instilled can overestimate body composition, including muscle mass, and as such potentially delay the recognition of PEW. Thus, for more accurate MFBIA in peritoneal dialysis patients, the dialysate should be drained out.