Comparison of equations of resting and total energy expenditure in peritoneal dialysis patients using body composition measurements determined by multi-frequency bioimpedance

Frailty, appendicular lean mass, osteoporosis and osteosarcopenia in peritoneal dialysis patients

INTRODUCTION

The pattern of chronic kidney disease mineral bone disorder (CKD-MBD) is changing with increasing numbers of elderly patients now treated by dialysis. The risk of falls and bone fractures increases with frailty and sarcopenia. As such we wished to review the association between osteoporosis and frailty and loss of appendicular lean mass (ALM).

METHODS

Dual-energy X-ray absorptiometry (DXA) was used to measure lumbar spine and femoral neck bone mineral density (BMD) and body composition. Osteoporosis and osteopenia were defined according to T scores. ALM was indexed to height (ALMI). Frailty was classified using the clinical frailty scale (CFS).

RESULTS

DXA scans from 573 patients, 57.8% male, 36.8% diabetic, mean age 61.0 ± 15.8 years, with a median 6.0 (2-20) months of treatment with PD were reviewed. Forty-two (7.3%) were classified as clinically frail, 115 (20%) osteoporotic, and 198 (34.6%) ALMI meeting sarcopenic criteria, with 43% of osteoporotic patients being osteosarcopenic. In a multivariable model, femoral neck BMD was associated with weight, standardised β (St β) 0.29, p = 0.004, ALM St β 0.11, p = 0.03 and Black vs other ethnicities St β 0.19, p = 0.02, and negatively with age St β -0.24, p < 0.001, and frailty St β -2.1, p = 0.04. Z scores (adjusted for gender and age) were associated with ALMI (r = 0.18, p < 0.001).

DISCUSSION

Osteoporosis is increasing with the numbers of elderly dialysis patients. As frailty and sarcopenia increase with age, then the risk of falls and bone fractures increases with osteosarcopenia. Whether interventions with exercise and nutrition can improve bone heath remains to be determined.

SARC-F and SARC-CalF are associated with sarcopenia traits in hemodialysis patients

BACKGROUND

The SARC-F questionnaire assesses sarcopenia risk. The addition of a calf circumference measurement, known as SARC-CalF, has been recently proposed. We investigated possible associations of SARC-F and SARC-CalF with sarcopenia traits in patients undergoing hemodialysis.

METHODS

Thirty patients (17 men; 57 ± 15 years) were enrolled. Sarcopenia risk was assessed by SARC-F (≥4) and SARC-CalF (≥11). Probable (low muscle strength or low skeletal muscle mass [SMM]) and confirmed (both) sarcopenia were diagnosed as recommended by the revised European Working Group on Sarcopenia in Older People. Muscle strength was assessed by handgrip strength (HGS) and five-time sit-to-stand test (STS-5), and physical performance was evaluated by gait speed. SMM was assessed by bioelectrical impedance.

RESULTS

Sarcopenia risk by the SARC-F and SARC-CalF were found in 23% (n = 7) and 40% (n = 12) patients, respectively. The SARC-F and SARC-CalF were both associated with physical function, but not with SMM. Probable sarcopenia by HGS was associated with SARC-F and SARC-CalF. Moreover, both showed moderate Kappa agreement with slowness and probable sarcopenia by HGS and/or STS-5, but only SARC-CalF with probable sarcopenia by HGS. A larger sensitivity was found for SARC-CalF than SARC-F in detecting probable sarcopenia by HGS (70% vs 30%) and by HGS and/or STS-5 (63% vs 44%).

CONCLUSION

SARC-F and SARC-CalF are associated with sarcopenia traits in patients undergoing hemodialysis. SARC-CalF seems to be more strongly associated with sarcopenia traits and present a higher sensitivity for probable sarcopenia than SARC-F, as it adds a direct measurement.

Novel equation for estimating resting energy expenditure in patients with chronic kidney disease

BACKGROUND

In chronic kidney disease (CKD), determining energy expenditure is the precondition for recommending energy intake in nutrition management.

OBJECTIVES

We aimed to develop and validate a resting energy expenditure (REE) equation for patients with CKD.

METHODS

This cross-sectional study enrolled 300 patients with CKD (stages 3-5) according to inclusion and exclusion criteria. Stepwise linear regression analysis was used to derive a new REE equation (eREE-CKD) according to actual REE (aREE) measured using indirect calorimetry in the development dataset. The eREE-CKD value was then validated with aREE in the validation dataset and compared with values from existing equations obtained in general populations, namely, the Harris-Benedict, Mifflin, WHO, and Schofield equations in terms of bias, precision, and accuracy.

RESULTS

The eREE-CKD equation: eREE-CKD (kcal) = (1 if male; 0 if female) × 106.0 - [1 if diabetes mellitus (DM); 0 if non-DM] × 51.6 - 4.7 × age (y) + 13.1 × weight (kg) + 645.5 (R2 = 0.779).The bias, precision, and accuracy (percentage of estimates that differed >20% from the measured REE) of the eREE-CKD equation were -0.4 (IQR: -29.8, 23.8) kcal, 98.4 (IQR: 79.5, 116.6) kcal, and 5.4%, respectively with indirect calorimetry as the reference method. Both bias and precision of the eREE-CKD were significantly better than the Harris-Benedict, WHO, and Schofield equations (P < 0.001) and similar to the Mifflin equation (P = 0.125 for bias and 0.268 for precision). Accuracy of the eREE-CKD was significantly better than the Harris-Benedict, WHO, Mifflin, and Schofield equations (P < 0.001). Bias, precision, and accuracy of the eREE-CKD equation were consistent when applied to subgroups categorized according to high-sensitivity C-reactive protein concentrations and CKD stages, respectively.

CONCLUSIONS

The eREE-CKD equation using age, sex, weight, and DM data could serve as a reliable tool for estimating REE in patients with CKD. This trial was registered at clinicaltrials.gov as NCT03377413.

Screening Tests for Sarcopenia in Patients with Chronic Kidney Disease

BACKGROUND

Patients with chronic kidney disease (CKD) are at increased risk of muscle wasting. Screening tools for sarcopenia, including the Sarc-F questionnaire are now advocated for clinical practice. We wished to compare using the Sarc-F tool with standard measurements of hand grip (HGS) strength and appendicular muscle mass index (APMI).

METHODS

We retrospectively reviewed Sarc-F questionnaires completed by patients with CKD, along with contemporaneous measurements of HGS and bioimpedance measured APMI.

RESULTS

146 patients; 94 male (64.4%), mean age 70.5 ± 15 years, body mass index 28.7 ± 6.3 kg/m² were screened, and 46 screened positive for sarcopenia, with a lower median HGS (19.3 (14.2-24.7) vs 25.6 (19.7-32) kg) and greater body fat (38.3 ± 11.5 vs 30.6 ± 11.5%), both p < 0.001,, with more non-white ethnicity (63 vs 44%), p < 0.05, but there were no other differences. Step-wise adding HGS, and then APMI cut offs, the prevalence of sarcopenia fell from 31.5% to 20.7-24.7% and 2.8-4.8% respectively, with 45.5-62.8% having reduced HGS strength and 11.0-28.1% reduced APMI, depending on which guidelines were applied. Using the most recent European, and ethnicity adjusted cut-off values then there were no statistical differences in the prevalence of sarcopenia with or without the Sarc-F screening tool.

CONCLUSIONS

By starting with the Sarc-F screening tool, a number of our patients with CKD would then have been excluded from subsequent investigation for sarcopenia. However, overall screening with the Sarc-F tool did not lead to a significant difference in the prevalence of sarcopenia, when using current and ethnicity adjusted guidelines, compared to combining HGS and APMI alone.

Comparison between standard single chamber versus dual chamber low glucose degradation product peritoneal dialysis fluids

Dual chamber (DC) peritoneal dialysis (PD) dialysates contain fewer glucose degradation products (GDPs), so potentially reducing advanced glycosylation end products (AGEs), which have been reported to increase inflammation and cardiovascular risk. We wished to determine whether use of DC dialysates resulted in demonstrable patient benefits. Biochemical profiles, body composition, muscle strength, and skin autofluorescence measurements of tissue AGEs (SAF) were compared in patients using DC and standard single chamber dialysates. We studied 263 prevalent PD patients from 2 units, 62.4% male, mean age 61.8 ± 16.1 years, 78 (29.7%) used DC dialysates. DC patients were younger (55.9 ± 16.4 vs. 64.2 ± 15.4 years), and more had lower Davies comorbidity score (median 1 (0-1) vs. 1 (0, 2)), slower peritoneal transport (D/P creatinine 0.67 ± 0.12 vs. 0.73 ± 0.13), greater extracellular water-to-total body water (ECW/TBW) ratio (0.46 ± 0.05 vs. 0.42 ± 0.06), all P < .001, whereas there were no differences in the duration of PD (median (IQR) 19 (8-32) vs. 14 (8-23) months), residual renal function (Kt/V_urea 0.71 ± 0.71 vs. 0.87 ± 0.82), urine volume (642 (175-1200) vs. 648 (300-1200) mL/day), hand grip strength (26.9 ± 10.5 vs. 24.9 ± 10.7 kg), C-reactive protein (4(1-10) vs. 4(2-12) mg/L), and SAF (median 3.60 (3.02, 4.40) vs. 3.50 (3.00, 4.23)) AU. In our cross-sectional observational study, we were not able to show a demonstrable advantage for using low GDP dialysates over conventional glucose dialysates, in terms of biochemical profiles, residual renal function, muscle strength, or tissue AGE deposition. More patients using low GDP dialysates were slower peritoneal transporters with higher ECW/TBW ratios.

A Comparison of the Indirect Calorimetry and Different Energy Equations for the Determination of Resting Energy Expenditure of Patients With Renal Transplantation

OBJECTIVE

We aimed to evaluate the agreement between the resting energy expenditure (REE) obtained by indirect calorimetry and eight prediction equations in adult patients with renal transplantation and a newly developed REE prediction equation for use in patients with renal transplantation in the clinic.

METHODS

A total of 51 patients (30 males and 21 females) were involved in the study. The REE was measured by indirect calorimetry and compared with the previous prediction equations. The agreement was assessed by the interclass correlation coefficient and by Bland-Altman plot analysis.

RESULTS

No significant difference was found in terms of age and body mass index between the genders. Differences between the predicted and measured REEs were maximum in the Bernstein equation (-478 kcal) and minimum in the Cunningham equation (-69 kcal). It was found that underprediction values varied from 27.5% (chronic kidney disease equation) to 98.0% (Bernstein equation). The highest overprediction value was found in the Schofield equation (17.7%). The Cunningham equation and the new equation had the lowest root mean square error (265 kcal/day). In this study, fat-free mass (FFM) was found to be the most significant variable in multiple regression analysis (r²: 0.55). The new specific equation based on FFM was generated as 424.2 + 24.7∗FFM (kg). Besides that, it was found that the new equation and Cunningham equation were distributed randomly according to Bland-Altman analysis. A supplementary new equation based on available anthropometric measurements was developed as -1996.8 + 19.1∗height (cm) + 7.2∗body weight (kg).

CONCLUSION

This study showed that most of the predictive equations significantly underestimated REE. In patients with renal transplantation, if the REE is not measurable by indirect calorimetry, the use of the proposed equations will be more accurate.

Glucose absorption from peritoneal dialysate is associated with a gain in fat mass and a reduction in lean body mass in prevalent peritoneal dialysis patients

The majority of peritoneal dialysates use glucose to generate an osmotic gradient for the convective removal of water and Na. Although glucose can potentially be absorbed, previous studies have failed to establish whether this leads to increased fat weight gain. We measured body composition using bioimpedance in peritoneal dialysis (PD) patients, electively starting PD, attending for their first assessment of peritoneal membrane function after 2-3 months, and then after 12 months. We studied 143 patients: eighty-nine (62·2 %) males, fifty-three (37·1 %) diabetics, mean age 61·3 (SD 14·9) years, with ninety (62·1 %) patients treated by automated PD cyclers with a daytime icodextrin exchange and thirty-seven (25·9 %) by continuous ambulatory PD. Median fat mass increased by 1·8 (-0·5 to 4·1) kg, whereas fat-free mass fell -1·3 (-2·9 to 1·0) kg, and the increase in fat mass was negatively associated with the fall in soft lean mass (r -0·41, P < 0·001). Increased fat mass was associated with measured peritoneal glucose absorption (r 0·69, P < 0·001), and glucose absorption was associated with the amount of 22·7 g/l glucose dialysate (OR 2·0, 95 % CI 1·5, 2·5, P < 0·001), peritoneal urea clearance (OR 9·5, 95 % CI 2·4, 37·1, P = 0·001) and male sex (OR 4·8, 95 % CI 1·5, 14·9, P = 0·008). We report an observational study in prevalent PD patients following body composition from their first assessment of PD membrane function for approximately 12 months, and despite the majority of patients prescribed icodextrin, we have demonstrated not only an association between intra-peritoneal glucose absorption and fat weight gain but also loss of fat-free mass.

Sodium loss, extracellular volume overload and hypertension in peritoneal dialysis patients treated by automated peritoneal dialysis cyclers

INTRODUCTION

Achieving sodium balance is important for peritoneal dialysis patients, as sodium excess may lead to hypertension and extracellular water expansion. We wished to determine whether greater sodium removal had adverse consequences.

METHODS

We calculated 24-h urinary and peritoneal sodium losses in peritoneal dialysis patients treated by automated cyclers, when attending for peritoneal membrane and bioimpedance assessments.

RESULTS

We reviewed 439 peritoneal dialysis patients, 56.7% male, average age 54.6 years, median sodium loss 110 (68-155) mmol/day. Sodium loss was strongly associated with urine volume, r = 0.37, protein nitrogen appearance rate, r = 0.29, and body cell mass, r = 0.21, all p < 0.001. We found no association with blood pressure or anti-hypertensive medication prescription, or extracellular water. On multivariable logistic regression analysis, sodium loss was associated with greater urine output, odds ratio 1.001, 95% confidence interval 1.00-1.001, p < 0.001, and protein nitrogen appearance (odds ratio 1.023, confidence interval 1.006-1.04), p = 0.008. Adjusting for body weight, sodium loss was associated with urine output (odds ratio 1.001, confidence interval 1.001-1.002, p < 0.001), and negatively with body fat index (odds ratio 0.96, confidence interval 0.93-0.99, p = 0.008) and co-morbidity grade (odds ratio 0.58, confidence interval 0.36-0.39, p = 0.023).

CONCLUSION

Heavier peritoneal dialysis patients with greater estimated dietary protein intake (protein nitrogen appearance), those with greater residual renal function and peritoneal clearances, along with lower co-morbidity, had greater daily sodium losses. Adjusting for body weight, then sodium losses were greater with higher daily urine output, and lower in patients with proportionately more body fat and co-morbidity. Sodium losses would appear to primarily determined by body size and not associated with hypertension or extracellular water expansion.

A pilot study investigating the effect of pedalling exercise during dialysis on 6-min walking test and hand grip and pinch strength

Introduction:

Haemodialysis patients are at an increased risk of sarcopenia. Physical inactivity is now recognised as a major cause of muscle wasting in haemodialysis patients. It is unclear as to what and how much exercise is required to show benefit. We therefore performed a pilot study of cycling during haemodialysis.

Methods:

Patients underwent a progressive submaximal individualised cycling exercise, 3× a week during haemodialysis for 4 months using bed-cycle ergometers. Body composition was measured by multifrequency segmental bioimpedance and muscle function by 6-min walking test, and hand grip strength and pinch strength.

Results:

In total, 56% of patients in a dialysis centre fulfilled exercise study inclusion criteria and 13 (72.2%) of 18 patients completed the exercise programme, with the mean age of 64.0 ± 16.6 years and 76.9% being male. The 6-min walking test increased following exercise from 349 ± 105 to 398 ± 94.2 m, p < 0.05, as did both hand grip strength and pinch strength, with 20.4 ± 9.1 versus 23.4 ± 9.9 kg, p < 0.01, and 4.3 ± 1.8 versus 5.9 ± 2.4 kg, p < 0.05, respectively. There were no changes in appendicular muscle mass or other body composition detected with bioimpedance in either the exercise group, or 21 control patients, propensity matched for body composition, comorbidity and frailty. Muscle strength did not change in the control group. Haemodialysis sessional Kt/Vurea was greater at the end of the exercise programme compared to controls (1.63 ± 0.63 vs 1.21 ± 0.12, p < 0.01).

Conclusion:

The majority of dialysis centre patients met our exercise study entry criteria and could potentially benefit from cycling during haemodialysis. We found that muscle function and strength improved after a 4-month, thrice weekly cycling exercise programme.

Estimating Dietary Protein Intake in Peritoneal Dialysis Patients: The Effect of Ethnicity

Kidney dialysis patients with sarcopenia have increased mortality. Clinical guidelines recommend peritoneal dialysis (PD) patients have a target daily protein intake to prevent sarcopenia. Protein intake is estimated from total daily urea losses in urine and peritoneal dialysate to assess the protein equivalent of nitrogen appearance rate adjusted for body weight (nPNA). Dietary habits differ among ethnic groups, so we reviewed nPNA and body composition in a multi-ethnic PD population. Body composition was measured with multifrequency bioimpedance in 598 patients (301 white, 136 black, 123 South-Asian, and 38 Asian-Pacific). South-Asians had a lower nPNA compared with white and black individuals (Randerson 0.80 ± 0.21 vs 0.88 ± 0.24 and 0.85 ± 0.24 g/kg/day, Blumenkrantz 0.97 ± 0.14 vs 1.04 ± 0.22 and 0.99 ± 0.22 g/kg/day, Bergström 0.87 ± 0.4 vs 0.95 ± 0.24 and 0.92 ± 0.24 g/kg/day all p < 0.001). South-Asians had lower weights (68.9 ± 14.9 vs 74.4 ± 16.6 and 73.5 ± 16.3 kg, p < 0.001), and although of similar body mass index (25.9 ± 4.9 vs 28.5 ± 4.9 and 26.5 ± 5.2 kg/m²), had both lower skeletal muscle and appendicular muscle mass indexed for height (9.08 ± 1.45 vs 9.89 ± 1.62 and 10.1 ± 1.85, p < 0.001; and 6.95 ± 1.39 vs 7.68 ± 1.48 and 7.67 ± 1.58 kg/m²p < 0.01). South-Asian patients had a lower calculated basal metabolic rate (BMR) (1,358 ± 218 vs 1,487 ± 257 and 1,489 ± 271 kcal/day, p < 0.001).Asian PD patients, particularly South-Asians, have lower dietary protein intakes when calculated by nPNA. However, South-Asians had lower measured muscle mass and calculated BMR. As such, dietary protein intake targets derived from studies in 1 ethnic group are not necessarily applicable for all patients, as those with less muscle mass and lower BMR may well need less daily protein intake to maintain homeostasis.

Peritoneal Protein Losses Depend on More Than Just Peritoneal Dialysis Modality and Peritoneal Membrane Transporter Status

Peritoneal protein clearance (PPCl) depends upon vascular supply and size selective permeability. Some previous reports suggested PPCl can distinguish fast peritoneal membrane transport due to local or systemic inflammation. However, as studies have been discordant, we wished to determine factors associated with an increased PPCl. Consecutive patients starting peritoneal dialysis (PD) who were peritonitis-free were studied. Data included a baseline peritoneal equilibration test (PET), measurement of dialysis adequacy, 24-h dialysate PPCl and body composition measured by multifrequency bioimpedance. 411 patients, mean age 57.2 ± 16.6 years, 60.8% male, 39.4% diabetic, 20.2% treated by continuous ambulatory peritoneal dialysis (CAPD) were studied. Mean PET 4-h Dialysate/Serum creatinine was 0.73 ± 0.13, with daily peritoneal protein loss 4.6 (3.3-6.4) g, and median PPCl 69.6 (49.1-99.6) mL/day. On multivariate analysis, PPCl was most strongly associated with CAPD (β 0.25, P < 0.001), extracellular water (ECW)/total body water (TBW) ratio (β 0.21, P < 0.001), skeletal muscle mass index (β 0.21, P < 0.001), log N-terminal brain natriuretic peptide (NT-proBNP) (β 0.17, P = 0.001), faster PET transport (β 0.15, P = 0.005), and normalized nitrogen appearance rate (β 0.13, P = 0.008). In addition to the longer dwell times of CAPD, greater peritoneal creatinine clearance and faster PET transporter status, we observed an association between increased PPCl and ECW expansion, increased NT-proBNP, estimated dietary protein intake and muscle mass, suggesting a link to sodium intake and sodium balance, increasing both ECW and conduit artery hydrostatic pressure resulting in greater vascular protein permeability. This latter association may explain reports linking PPCl to patient mortality.