Influence of protein catabolic rate on nutritional status, morbidity and mortality in elderly uraemic patients on chronic haemodialysis: a prospective 3-year follow-up study

It has been recently reported that elderly chronic haemodialysis(CHD) patients have a reduced protein catabolic rate (PCRn)in spite of an adequate K_t/V. However until now the long-termconsequences of this fact on the nutritional status, morbidity,and mortality were not known. This prospective study evaluates,over a period of 3 years, the effect of the reduced PCRn onsome nutritional parameters, morbidity and mortality in CHDpatients older than 65 years with adequate and stable K_t/V.Over the period 1990–1993 we evaluated 42 CHD patientsover 65 years (mean±SD 72±5 years). PCRn, totalserum proteins, serum albumin concentration, body weight, bodymass index (BMI) and serum transferrin were determined at thestart of the study and followed yearly until the end of observation.The incidence of hospitalization/patient-year, the mortalityrate and the causes of death were also recorded. All the patientswere managed to maintain a K_t/V>0.9 throughout the study.Twenty-two patients (Group A), mean age 70±4 years, completedthe entire period of observation. Their K_t/V was 1.10±0.12,PCRn was 0.95±0.12 g/kg/day, and serum albumin concentrationwas 40.2±1.5 g/l, and these did not change significantly.The other parameters also remained stable over time. Twentypatients (Group B) died. Their mean age was 74±6 years.This group's K_t/V was 1.11±0.15, PCRn was 0.94±0.18g/kg/day, and serum albumin concentration was 39±3.1g/l, and there were no significant variations between the startand the end of observation for all the parameters studied. Therewere no differences between the two groups of patients at thestart of observation for all the parameters with the exceptionof age, which was significantly higher in patients in GroupB (P=0.017). The data derived by the Cox proportional hazardsregression model showed that PCRn and serum albumin concentrationwere not significant predictors of death, as well as K_t/V, totalserum proteins, BMI, total number of risk factors and numberof hospital admissions/patient-year, but confirmed the predominantrole of age (P<0.009) in predicting and conditioning thesurvival of patients. In conclusion this prospective study showsthat elderly CHD patients with adequate and stable K_t/V havePCRn values lower than those commonly suggested as necessaryto prevent chronic malnutrition. However, this reduced proteinintake did not exert any specific negative influence on thenutritional status, morbidity and mortality after a follow-upof 3 years. It is possible that, in this group of patients,a declining PCRn with age does not indicate impending malnutritionand does not influence morbidity and mortality. Therefore ageremains the strongest factor influencing mortality.     

Kt/V reach rate is associated with clinical outcome in incident peritoneal dialysis patients

BackgroundThe urea clearance index (Kt/V) is an important index for predicting the clinical outcome of peritoneal dialysis (PD) patients, but it changes with time depending on the clinical condition. This study aimed to investigate the association between the Kt/V reach rate (defined as the percentage of Kt/V measurements that reached ≥ 1.70) and clinical outcome in incident PD patients.MethodsIn this retrospective cohort study, 210 patients were enrolled from the First Affiliated Hospital of Zhengzhou University from 1 January 2013 to 31 October 2019. The target Kt/V reach rate in the first year was applied as the predictor variable. Kaplan-Meier survival curves were drawn to evaluate differences in prognosis. The association between Kt/V reach rate and the composite clinical outcome (death or transfer to hemodialysis) was tested by Cox regression analysis.ResultsThe dialysis adequacy group (Kt/V reach rate 3/3 times) and the dialysis intermittent adequacy group (1/3 or 2/3 times) had significantly better clinical outcomes than the dialysis inadequacy group (0/3 times). There was no difference in clinical outcome between the lower-rate group (reach rate 1/3 times) and the higher-rate group (2/3 times). Compared with the dialysis inadequacy group, the dialysis intermittent adequacy group and dialysis adequacy group had significantly lower risks of the composite outcome (HR 0.487, 95% CI 0.244–0.971, p = 0.041; HR 0.150, 95% CI 0.043–0.520, p = 0.003) in the fully adjusted analysis.ConclusionHigher Kt/V reach rates are associated with a better prognosis in incident PD patients.     

Protein intake does not depend on the dose of dialysis delivered--provided Kt/V is adequate

BACKGROUND: A link between malnutrition and the dialysis dose has been recentlypostulated on the basis of the direct relationship between Kt/Vand nPCR and an increase in dialysis therapy has been also proposedin malnourished patients or when nPCR is less than 1 g/kg b.w.,but the clinical meaning of such a relationship is unclear. DESIGN: Both dietary protein intake and nPCR were simultaneously determinedin a selected population of 35 well-dialysed patients (Kt/V>0.8)and were related to the delivered dialysis dose. RESULTS: No relationship was found between measured Kt/V (1.10 ±0.20) and dietary protein intake (PI, 0.98 ± 0.20 g/kg)and similarly no relationship was evident between the dialysisdose and nPCR (0.99 ± 0.20 g/kg). Although the mean nPCRvalue was similar to that of protein intake, nPCR exceeded proteinintake when PI was less than 1 g/kg b.w. CONCLUSION: Our results demonstrate that if the dialysis dose is adequate,protein intake is a dialysis—independent or patient—dependentvariable. They also show that at least 0.9 to 1.0 g proteinper kg b.w are required to maintain nitrogen balance even inwell-dialysed patients.     

Estimating total urea removal and protein catabolic rate by monitoring UV absorbance in spent dialysate.

BACKGROUND: Dialysate-based, on-line measurements of Kt/V and protein catabolic rate (PCR) in dialysis patients have been considered more accurate compared with measurements on the blood side during dialysis. The primary aim of this study was to compare total removed urea (TRU) and PCR, normalized to body weight (nPCRw), obtained by three dialysate-based methods: (i) on-line ultraviolet (UV) absorbance of the spent dialysate; (ii) total dialysate collection (TDC), as reference method; and (iii) Urea Monitor 1000 (UM) from Baxter Healthcare Corp. METHODS: We studied 10 uraemic patients on chronic, thrice-weekly haemodialysis. We made absorption measurements (UV radiation) on-line with a spectrophotometer connected to the fluid outlet of the dialysis machine, with all spent dialysate passing through an optical cuvette for single-wavelength measurements. UV absorbance measurements were compared with TDC and the UM. RESULTS: nPCRw obtained with UV absorbance was 0.82+/-0.17, that from TDC 0.81+/-0.18, and that measured by UM 0.87+/-0.18, which was significantly higher than the results of the other methods. The difference between nPCRw calculated by TDC and by UM was -0.05+/-0.06, showing a slightly lower SD than the difference between nPCRw by TDC and UV absorbance, -0.01+/-0.07. CONCLUSION: The study demonstrates that TRU, and consequently PCR, can be estimated by on-line measurement of the UV absorption in the spent dialysate.     

Sequential change of asymmetric dimethylarginine levels after initiation of peritoneal dialysis in patients with end-stage renal disease

Background: We hypothesized that the asymmetric dimethylarginine (ADMA) metabolism in end‐stage renal disease may be linked to the rate of protein turnover and to the vast pool of amino acids. In order to determine a correlation between the plasma levels of ADMA and the protein catabolic rate, we measured the ADMA levels as well as nutritional markers such as the normalized protein catabolic rate (nPCR) in patients with newly initiated continuous ambulatory peritoneal dialysis (CAPD). Methods: Twenty‐four patients were recruited for this study. All patients were on the standard CAPD protocol, and followed for at least 1 year. Blood samples were collected at baseline before the initiation of peritoneal dialysis, and every 6 months for 1 year. The blood parameters studied included the serum albumin, total cholesterol, glucose, urea nitrogen, creatinine and ADMA. Peritoneal equilibrium test and measurements of weekly Kt/Vurea and nPCR were performed within 4 weeks of the blood sampling. Results: The change of ADMA levels over 1 year was positively correlated with that of haemoglobin (r = 0.592, P = 0.002) and nPCR during the same period (r = 0.508, P = 0.026). Conclusion: The findings of our study suggest that nPCR might influence the change of ADMA levels after initiation of CAPD.     

Effect of prescribing a high protein diet and increasing the dose of dialysis on nutrition in stable chronic haemodialysis patients: a randomized, controlled trial.

BACKGROUND: Protein requirements in stable, adequately dialysed haemodialysis patients are not known and recommendations vary. It is not known whether increasing the dialysis dose above the accepted adequate level has a favourable effect on nutrition. The aim of this study was to determine whether prescribing a high protein diet and increasing the dose of dialysis would have a favourable effect on dietary protein intake and nutritional status in stable, adequately dialysed haemodialysis patients. Effects on hyperphosphataemia and acidosis were also studied. METHODS: Patients were randomized to a high dialysis dose (HDD) group (target Kt/V(eq) of 1.4) or a regular dialysis dose (RDD) group (target Kt/V(eq) of 1.0). All patients were prescribed a high protein (HP) diet [1.3 g/kg of ideal body weight (IBW)/day] and a regular protein (RP) diet (0.9 g/kg/day), each during 40 weeks in a crossover design. In 50 patients, 23 in the HDD and 27 in the RDD group follow-up was > or =10 weeks. These patients, aged 56+/-15 years, were included in the analysis. Nutritional status was assessed by anthropometry, plasma albumin and a nutritional index. RESULTS: Delivered Kt/V(eq) in the HDD group (1.26+/-0.14) was significantly higher than in the RDD group (1.02+/-0.08). Protein intake estimated from total nitrogen appearance (PNA) measurements and food records (DPI) was significantly higher during the HP diet (PNA(IBW), 1.01+/-0.18 g/kg/day; DPI(IBW), 1.15+/-0.18 g/kg/day) than during the RP diet (PNA(IBW), 0.90+/-0.14 g/kg/day; DPI(IBW), 0.94+/-0.11 g/kg/day). Increasing the dialysis dose did not increase protein intake either during the HP or RP diet. Plasma albumin (41.9+/-3.0 g/l) lean body mass (107+/-15% of normal values) and the nutritional index did not differ between the dialysis dose groups or protein diets and remained stable overtime. Dry body weight (97+/-14%) and total fat mass increased over time in the HDD group, but remained stable in the RDD group suggesting an effect of dialysis dose on energy balance. There was no effect of the protein diets on dry body weight or total fat mass. Plasma phosphate levels and oral bicarbonate supplements were lower in the HDD group, but were comparable between the protein diets. CONCLUSIONS: Prescribing a HP diet resulted in a modest increase in actual protein intake, but increasing dialysis dose did not have a contributing effect. A HP diet or increasing the dialysis dose did not have a favourable effect on the nutritional status. A dietary protein intake of at least 0.9 g/kg IBW/day appears to be sufficient for adequately dialysed haemodialysis patients without overt malnutrition.     

KT/V and protein catabolic rate determination from serial urea measurement in the dialysate effluent stream

A bloodless technique of evaluating protein catabolic rate (PCR) and KT/V (K, clearance; T, dialysis time; V, urea distribution volume) in hemodialysis patients is presented based on serial measurement of urea in the dialysate effluent stream. PCR follows from equating urea generation and urea removal over a 7 day cycle, changes in body stores being comparatively negligible: PCR = 0.026 [U1 + U2 + U3]/BWdry + 0.17, where U1 is the amount of urea in mmol appearing in the dialysate for each session in the 7 day period. KT/V is obtained from the slope of the natural logarithm of spent dialysate urea concentration-time plot: KT/V = [- slope.T + 3.delta BW/BWdry]/[1 - 0.01786.T(hr], where delta BW = amount ultrafiltered in liters. The dialysate-based approach was validated and compared with conventional urea kinetic modeling (UKM) for 17 patients studied for three consecutive dialyses. The dialysate-based and UKM values of PCR agreed well when in vivo clearance values based on total dialysate collection were used for UKM. KT/V values agreed poorly on a session-by-session basis but were nearly equivalent when averaged for the three dialyses of the week. These findings lay the foundation for UKM automation with a urea sensor in the effluent dialysate stream.     

Heart rate variability predicts mortality in peritoneal dialysis patients

Abstract

Background: The predictive value of heart rate variability (HRV) in peritoneal dialysis (PD) has never been tested. Methods: In this study, the associations between HRV measures and the mortality in 81 PD patients were analyzed. HRV was measured by using 5-min recordings of a stationary system by a standardized method. Both time domain and frequency domain parameters were analyzed. Results: During a follow-up period of 43.78?±?14.77 months, 25 patients died, four patients were transferred to hemodialysis. Of the 81 patients, the time domain parameters, such as the standard deviation of differences between adjacent normal sinus to normal sinus (NN) intervals (SDSD) and the square root of the mean of the squared differences between adjacent normal NN intervals (RMSSD), were higher; the frequency domain parameters, such as the ratio of low-frequency power to high-frequency power (LF/HF) and the normalized LF, were lower, and the normalized HF was higher in the non-survived group as compared with the survived group. A Cox proportional hazards model analysis revealed that, of the HRV measures, decrease of the normalized LF, LF/HF and increase of rMSSD, SDSD, normalized HF had significant predictive value for mortality. After adjustment for other univariate predictors including age, urine volume, renal Kt/V, high-sensitivity C-reactive protein (hs-CRP), the predictive value of decreased LF/HF remained significant. Kaplan–Meier survival analysis showed mortality rate was much higher in patients with a low LF/HF (median value of 1.56). Conclusion: The decreases of LF/HF which reflects impaired sympathetic nerve regulation is an independent predictor of mortality in PD patients.     

Factors influencing long-term survival in patients on chronic dialysis

Japan has the highest prevalence of dialysis patients in the world. According to the Annual Report of the Japanese Society for Dialysis Therapy (JSDT; 2002), the total dialysis population was 229538 (1801.5 patients per million population) at the end of 2002. The annual crude mortality rate has been less than 10%. Survival rates in the incident dialysis patients were 0.874 for 1 year, 0.609 for 5 years, and 0.391 for 10 years. Despite the increased acceptance for dialysis of elderly patients, those with comorbid conditions, and those with diabetes mellitus, the adjusted hazard ratios for death have been improving since 1983. This improvement was obtained by delivering a dialysis dose of Kt/V 1.33 and dialysis sessions of 4h. Independently of the JSDT registry, there exists a local dialysis registry in Okinawa, the Okinawa Dialysis Study (OKIDS) registry, in which are filed the records of every chronic dialysis patient from the beginning of dialysis therapy in 1971 to the end of 2000. Several outcome studies have been conducted to determine the factors related to survival, using the data in that registry. There are distinct differences in environmental and socioeconomic conditions and lifestyles within a given country, and between countries and ethnic groups, that may affect the survival of dialysis patients. In this article, both the JSDT registry and OKIDS data are reviewed in order to identify factors related to the survival of chronic dialysis patients.     

A dramatic reduction of normalized protein catabolic rate occurs late in the course of progressive renal insufficiency.

BACKGROUND: Spontaneous reduction in dietary protein intake is a recognized feature of severe renal failure, and previous studies have suggested that this may occur at an early stage of renal functional decline. METHODS: We examined the effects of progressive renal insufficiency on the normalized protein catabolic rate (nPCR) in 1282 patients (mean age 55.8+/-15.5 years; 60.4% male) over a 7 year period. All values of nPCR (n = 5082) obtained before commencement of dialysis were included. A total of 361 (28.2%) patients later developed end-stage renal failure and were started on dialysis. RESULTS: Cross-sectional analysis showed nPCR being significantly less at lower creatinine clearance. Mean nPCR was 1.17+/-0.31 at a clearance >50, 1.04+/-0.27 at 25-50, 0.93+/-0.21 at 10-25 and 0.74+/-0.18 at <10 ml/min. Mean nPCR in each clearance group was different from that in all other groups (P<0.001 in all cases). When nPCR was studied longitudinally in relation to time of initiation of dialysis, the fall in nPCR only became significant in the 3 months preceding initiation. Curve fitting suggested a two-phase exponential association between nPCR and renal function, a gentle decline of nPCR in mild and moderate renal failure culminating in a dramatic decline when CrCl reached 15 ml/min and weekly Kt/V(urea) 2.5. nPCR at dialysis initiation predicted survival on dialysis even when corrected for age, diabetes and non-renal co-morbid load. However, it was no longer significant when residual renal function was included in the model. The group initiating dialysis with a normal nPCR maintained this throughout the first 3 years on dialysis whilst the group initiating with a low nPCR, though improving initially, continued to have significantly lower nPCR levels throughout follow-up than their normal nPCR counterparts. CONCLUSION: A significant reduction of nPCR occurs late in progressive renal insufficiency and may predict the need for dialysis initiation. nPCR levels <0.8 at initiation predict future low nPCR levels and mortality on dialysis. The correlation between nPCR and CrCl in early renal insufficiency may be partly artefactual.     

Predictive value of dialysis adequacy and nutritional indices for mortality and morbidity in CAPD and HD patients. A longitudinal study

BACKGROUND: The effects of dialysis inadequacy on patient survival and nutritionalstatus and that of malnutrition on survival have not been clearlyassessed. Studies comparing dose/mortality and morbidity curveson continuous ambulatory peritoneal dialysis (CAPD) and on haemodialysis(HD) are also needed, to assess adequate treatment on CAPD. METHODS: We have evaluated the effects of age, 13 pretreatment risk factors,serum albumin, transferrin, normalized protein catabolic rate,Kt/V, normalized weekly creatinine clearance, residual renalfunction and subjective global assessment of nutritional statuson survival and morbidity, in a 3-year prospective study of68 CAPD and 34 HD patients. RESULTS: Survivals did not differ for CAPD and HD patients. In the Coxhazard regression model, age, peripheral vasculopathy, serumalbumin <3.5 g/dl and Kt/V < 1.0/treatment on HD and <1.7/weekon CAPD were independent factors negatively affecting survival.On the contrary, adjusted survivals were not affected by gender,modality, other comorbid factors, normalized protein catabolicrate, or subjective global assessment of nutritional status.Persistence of residual renal function significantly improvedsurvival. Observed and adjusted survival did not significantlydiffer for CAPD and HD patients with either low (HD, <1.0/treatment;CAPD, < 1.7/week) or high ( 1.0 and 1.7) Kt/V. On HD, adjustedsurvivals were similar for 1.0 Kt/V < 1.2 or 1.2. On CAPD,Kt/V 1.96/week was associated with definitely better survival,with only one death/23 patients versus 19/45, with Kt/V 1.96.Survival was not different for 1.96 Kt/V < 2.03 and 2.03.Normalized weekly creatinine clearance and wKt/V were positivelyrelated on CAPD (r 0.39, P<0.01) and wKt/V=1.96 correspondedto 58 litres of normalized weekly creatinine clearance. CONCLUSION: Indices of adequacy were predictors of mortality and morbidity,both on CAPD and HD, whereas normalized protein catabolic rateand subjective global assessment of nutritional status werenot. Serum albumin did not decrease during dialysis; hence itspredictive effect for survival is due to the predialysis conditionand not to dialysis-induced malnutrition.     

The effect of single and repeatedly high concentrations of C-reactive protein on cardiovascular and non-cardiovascular mortality in patients starting with dialysis.

BACKGROUND: Single measurements of C-reactive protein (CRP) predict cardiovascular mortality in dialysis patients. However, CRP can be temporarily elevated due to infections. Therefore, we investigated the effect of single and repeatedly high concentrations of CRP on cardiovascular and non-cardiovascular mortality in incident dialysis patients. METHODS: In the Netherlands Cooperative Study on the Adequacy of Dialysis (NECOSAD), patients starting with dialysis were enrolled between 1997 and 2002. From 635 patients, plasma CRP concentrations were determined at 3 and 6 months of follow-up. Concentrations >10 mg/l were regarded as 'high'. Patients were followed until time of death, or censored at the end of follow-up (1 May 2004). Cox regression models were performed to compare mortality between patients with repeatedly low CRP, with varying CRP and with repeatedly high CRP. RESULTS: At the end of follow-up, 247 patients had died, of which 107 patients died of cardiovascular disease (47.8%). Patients with low CRP(3 months) and high CRP(6 months) were at increased cardiovascular [adjusted hazard ratio (HR): 2.59, 95% CI: 1.25-5.37] and non-cardiovascular (adjusted HR: 2.18, 95% CI: 1.11-4.28) mortality risk compared with patients with low CRP on both occasions. Moreover, patients with high CRP on both occasions had a higher cardiovascular (adjusted HR: 1.51, 95% CI: 0.72-3.18) and non-cardiovascular (adjusted HR: 2.25, 95% CI: 0.96-5.28) mortality risk than patients with high CRP(3 months) and low CRP(6 months). CONCLUSIONS: Single and repeatedly high concentrations of CRP (>10 mg/l) are related to both cardiovascular and non-cardiovascular mortality in dialysis patients. A high CRP concentration, therefore, has implications for the treatment of cardiovascular as well as non-cardiovascular disease.     

Effect of the interaction between estimated glomerular filtration rate and serum uric acid on all-cause and cardiovascular mortality in patients on peritoneal dialysis

Objective To explore the effect of the interaction between estimated glomerular filtration rate (eGFR) and serum uric acid (SUA) on all-cause and cardiovascular mortality in patients on peritoneal dialysis (PD). Methods Patients who performed PD catheterization at the PD center of the First Affiliated Hospital of Sun Yat-sen University and had initiated PD therapy for over 3 months from January 2006 to December 2016 were enrolled and followed up until December 2018. Demographic data, baseline clinical and laboratory examination results of the patients were collected. Kaplan-Meier survival curve and Cox regression analysis were used to explore the correlation between SUA and all-cause mortality, cardiovascular mortality in different eGFR groups of PD patients. Results A total of 2 124 PD patients were enrolled with age of (47.0±15.2) years, among whom 1 269 patients were male and 536 patients had diabetes. The SUA level was (429±96) μmol/L and the median level of eGFR was 6.69(5.17, 8.61) ml?min-1?(1.73 m2)-1. After a median follow-up time of 42 months, 554 patients died, among whom 275 patients were cardiovascular death. The Cox regression analysis revealed that there was a significant interaction between eGFR and SUA on all-cause mortality (P=0.043). The Kaplan-Meier curve showed that the tertile 1 (SUA＜384 μmol/L) and tertile 3 (SUA＞460 μmol/L) group had significantly higher all-cause mortality (P=0.009) than the reference group of tertile 2 (SUA 384-460 μmol/L) in the higher eGFR group [eGFR＞6.69 ml?min-1?(1.73 m2)-1]but not in the lower eGFR. After adjusting for relevant demographic data, complications, biochemical results and other variables, in patients with higher eGFR, the risk of all-cause mortality increased by 0.2% (HR=1.002, 95%CI 1.000-1.003, P=0.019) for every 1 μmol/L increase in SUA. In addition, compared with the tertile 2 reference group, the tertile 3 group was independently correlated with higher risk of all-cause mortality (HR=1.670, 95%CI 1.242-2.245, P=0.001). Conclusions The eGFR and SUA level significantly interacts with all-cause mortality, and the higher SUA level in higher eGFR group is an independent risk factor for all-cause mortality in PD patients.     

Mineral metabolism and cardiovascular morbidity and mortality risk: peritoneal dialysis patients compared with haemodialysis patients.

BACKGROUND: The K/DOQI guideline for bone metabolism and disease in chronic kidney disease is predominantly based on studies in haemodialysis (HD) patients. However, in clinical practice, this guideline is also applied to peritoneal dialysis (PD) patients. To validate the implementation of this guideline in PD patients, we evaluated the associations between plasma concentrations outside the K/DOQI-targets and the risk of cardiovascular morbidity and mortality in incident PD patients compared with HD patients. METHODS: In a large prospective multicentre study in the Netherlands (The Netherlands Cooperative Study on the Adequacy of Dialysis, NECOSAD), we included patients starting PD or HD between 1997 and 2004. Relative risk of cardiovascular morbidity and mortality were estimated using time-dependent Cox regression modelling. RESULTS: We included 586 PD patients with mean age 52 +/- 15 years (66% males) and 1043 HD patients with mean age 63 +/- 14 years (58% males). Cardiovascular disease (CVD) was the reason for hospitalization in 102 PD and 271 HD patients. In HD patients, the relative risk of CVD-related hospitalization increased with elevated plasma calcium concentrations (hazard ratio: 1.4; 95% CI: 1.1-1.9). Cardiovascular mortality was significantly higher for phosphorus concentrations above the K/DOQI-threshold in PD (2.4; 95% CI: 1.3-4.2) and HD patients (1.5; 95% CI: 1.1-2.1), and for elevated Ca x P in PD (2.2; 95% CI: 1.3-3.8) and HD patients (1.5; 95% CI: 1.1-2.1). CONCLUSIONS: Plasma calcium concentrations above the K/DOQI-threshold increase the relative risk of CVD-related hospitalization in HD patients. Associations with cardiovascular mortality were more pronounced. Both in PD and HD patients with elevated plasma phosphorus and Ca x P concentrations, the cardiovascular mortality risk is increased. Therefore, it seems appropriate to adopt the current guideline in PD patients.     

The status on achieving Kt/Vurea target and its relation with residual renal function and clinical characteristics of peritoneal dialysis patients

ObjectiveTo explore the present status on achieving Kt/Vurea target in Chinese peritoneal dialysis (PD) patients and its relation with residual renal function (RRF) and clinical characteristics. Methods This was a cross-sectional study carried out in 5 PD centers in different area of China. Totally 681 clinical stable PD patients with duration≥3 months who completed dialysis adequacy and biochemical test during April 1st, 2011 and August 31st, 2011 were enrolled in this study. The demographic data and clinical characteristics were compared according to varied Kt/Vurea and RRF levels. Results (1)The total Kt/Vurea was 1.95±0.59,and total Ccr was （63.80±30.84）L·week-1·(1.73 m2) -1 for the whole group, there were 67.4% subjects achieving the Kt/Vurea target. (2) Patients achieving Kt/Vurea targetwere prone to be female and had smaller size with higher RRF and urine volume (P＜0.05). The serum calcium and phosphorus were controlled well in these patients (P＜0.05). They also had better higher cholesterol and low-density lipoprotein, and lower CRP level and less complications (P＜0.05). (3)Serum albumin was higher but inflammation and complications were less in patients with Kt/Vurea value≥1.7 and RRF≥2 ml·min-1·（1.73 m2）-1 (subgroup 1), as compared to those with Kt/Vurea≥1.7 but RRF＜2 ml·min-1·（1.73 m2）-1 (subgroup 2) and those with Kt/Vurea＜1.7(subgroup 3) (P＜0.05). The subgroup 2 and 3 were statistically different in these clinical indices, serum calcium [(2.22±0.21) mmol/L vs (2.14±0.24) mmol/L, P＜0.01], serum phosphorous [(1.43±0.47) mmol/L vs (1.66±0.52) mmol/L, P＜0.01], cholesterol [(4.91±1.29) mmol/L vs (4.62±0.99) mmol/L, P＜0.05], low-density lipoprotein [(2.86±0.96) mmol/L vs (1.13±0.61) mmol/L, P＜0.01], high-density lipoprotein [(1.08±0.33) mmol/L vs (2.20±0.72) mmol/L, P＜0.01]. (4)The Kt/Vurea was positively correlated with RRF (R2＝0.317); if RRF decreased 1 ml/min, the hazard of Kt/Vurea un-targeting increased 40.3%. Conclusions About 67.4% of PD patients can reach the Kt/Vurea target recommended by K/DOQI. RRF makes a great contribution to Kt/Vurea target. The clinical characteristics are poorer in patients who can not achieve the Kt/Vurea target, or with worse RRF.     

Adequacy of dialysis and nutritional status in CAPD

Urea kinetic modelling (UKM) was used to assess adequacy ofdialysis in 50 CAPD patients. Nutritional status was assessedfrom the measurement of visceral protein status (total protein,albumin, transferrin, immunoglobulins, complement), somaticprotein status (anthropometry), and dietary intake (1 week weigheddietary inventory and normalized protein catabolic rate (NPCR)from UKM). Morbidity was assessed from the peritonitis and admissionhistory. Mean Kt/V (corrected to x3 weekly dialysis) was 0.66 ±0.02. Dietary protein intake estimated from the NPCR (1.08±0.03g kg^–1 day^–1) correlated well (r=0.72, P<0.001)with that estimated from the dietary inventory (1.10±0.04g kg^–1 day^–1). There was a strong correlation betweenKt/V and NPCR corrected for actual weight (r=0.65, P<0.001),but when NPCR was corrected for IBW this correlation was weaker(r=0.35, P<0.05). Patients were divided by Kt/V into twogroups (>0.65, n=22 and <0.65, n=28). There were no significantdifferences in the indices of visceral protein status betweenthe two groups. Weight, height, BMI, fat free mass and arm musclearea were significantly greater in the group Kt/V<0.65. Residualrenal function (creatinine clearance) was higher in the groupKt/V>0.65 (3.8±0.7 versus 1.9±0.5 1/24 h, P<0.05)and plasma creatinine less (913±51 versus 1265±51µmol/l, P<0.001). Hb, potassium, bicarbonate, phosphate,alkaline phosphatase, PTH, and blood pressure were not different.Neither was there any difference between the two groups in anyof the indices of morbidity.     

Determinants of haemoglobin carbamylation in haemodialysis and peritoneal dialysis patients.

BACKGROUND: Carbamylation is an irreversible process of non-enzymatic modification of proteins by the breakdown products of urea. For haemoglobin (Hb), the extent of carbamylation is a marker of urea exposure and has been proposed as an indicator of the control of uraemia by dialysis, analogous to the use of Hb glycosylation in diabetic patients. METHODS: We performed a cross-sectional study of haemodialysis (HD) and peritoneal dialysis (PD) patients in order to study potential determinants of carbamylated Hb (CarbHb) and to investigate the relationship between CarbHb and established measures of dialysis dose/adequacy by multivariate analysis. RESULTS: In 80 HD patients, CarbHb was independently predicted by post-dialysis urea (r=0.40, P:<0.01), serum albumin (r=0.24, P:<0.05) and serum bicarbonate (r=-0.40, P:<0. 05). No correlation was found between CarbHb and measures of dialysis dose/adequacy (Kt/V, urea reduction ratio, weekly dialysis duration, and normalized protein catabolic rate (nPCR)). In 42 PD patients, serum urea was the only significant independent predictor of CarbHb (r=-0.51, P:=0.001). No relationship was found between CarbHb and Kt/V, corrected creatinine clearance (CrCl) or nPCR in PD patients. CONCLUSIONS: Serum urea is the most consistent independent predictor of CarbHb in dialysis patients. This association in combination with the lack of a relationship with conventional measures of dialysis dose and a positive relationship with serum albumin suggest that a single measurement of CarbHb is unlikely to be a useful indicator of the adequacy of dialysis.