The urea reduction ratio and serum albumin concentration as predictors of mortality in patients undergoing hemodialysis

Identifying patients at risk for hemodialysis underprescription

Underprescription of hemodialysis is an important barrier to adequate delivery of dialysis. We sought to determine which patient factors are associated with hemodialysis underprescription and to examine variation in prescription across facilities. For 721 randomly selected patients from all 22 chronic hemodialysis units in northeast Ohio, we calculated prescribed Kt/V based on dialyzer urea clearance at prescribed blood and dialysate flow (K), prescribed treatment time (t), and anthropometric volume (V). A minimum 'prescribed Kt/V' of 1.3 has been recommended to ensure an adequate 'delivered Kt/V' of 1.2. Using this criterion, 15% of patients had a low prescribed Kt/V. Prescribed Kt was strongly related to patient anthropometric volume but not to other patient characteristics (age, gender, race, cause of renal failure, number of years on dialysis, number of comorbid conditions). A 10-liter increase in V was associated with an 8.3-liter increase in prescribed Kt. However, a 13-liter increase in prescribed Kt would be needed to maintain a prescribed Kt/V of 1.3. As a result, the proportion of patients with low prescriptions increased from 2% of patients with V <35 liters to 42% of patients with V > or =50 liters. In addition, the prevalence of low prescriptions varied dramatically across facilities (range 0-47%) even after accounting for volumes of individual patients. Of the 109 patients with low prescription, 75% would achieve a prescribed Kt/V of 1.3 with less than 30 min of additional treatment time. In conclusion, large patients and patients at specific facilities are at increased risk for underprescription of hemodialysis. Most patients with low prescriptions would achieve a prescribed Kt/V of 1.3 with a modest increase in treatment time.

Improving Serum Albumin Levels in Hemodialysis Patients by a Continuous Quality Improvement Project

Protein nutrition and serum albumins predict present and future mortality and morbidity. The North East Albuquerque Dialysis Center undertook a quality improvement project to improve serum albumin levels in hemodialysis patients. The dialysis facility's quality assurance team evolved into a continuous quality improvement team just before this project. The timeline and steps in this evolution are presented. The continuous quality improvement project process analysis, interventions, and outcome rates are also described. The project has resulted in a rate of less than or equal to 10% of hemodialysis patients with serum albumins less than 3.4 for the past 3 years.

The role of the dietitian in a multicenter clinical trial of dialysis therapy: the Hemodialysis (HEMO) Study

The Hemodialysis (HEMO) Study is a randomized multicenter prospective clinical trial, supported by the National Institute of Diabetes, Digestive, and Kidney Diseases of the National Institutes of Health. The trial is designed to assess the effects of a standard versus higher dialysis dose and low versus high dialysis membrane flux on morbidity and mortality of chronic hemodialysis patients. The role of the dietitian in the HEMO Study is to support and maintain the nutritional status of randomized participants. To ensure participant safety, nutritional status is closely monitored by a variety of biochemical and participant-reported parameters. Serum albumin and equilibrated normalized protein catabolic rates are obtained monthly. Appetite assessment and dietary energy and protein intakes using a 2-day diet diary assisted recall are ascertained at baseline and on a yearly basis. Consumption of vitamins, minerals, and nutritional supplements, including oral enterals, tube feedings, and parenteral nutrition, is obtained at least once a year. In addition, anthropometry is performed at baseline and on a yearly basis. Prespecified changes in serum albumin level or body weight trigger action by the dietitian to prevent protein calorie malnutrition. The HEMO Study dietitians play a vital role in carrying out the nutrition program for the trial. The HEMO Study should provide important information about the natural history of the nutritional status of chronic hemodialysis patients and the impact of dialysis dose and dialysis membrane flux on these parameters.

[From the first symptoms to terminal renal failure: need for a nephrologic follow-up]

PURPOSE

As patients with chronic renal failure are frequently referred late to nephrologists, we decided to quantify the magnitude of late referral and its consequences.

METHODS

We studied retrospectively an inception cohort of 62 patients starting dialysis (either hemodialysis or continuous ambulatory peritoneal dialysis) during 1993 with a 4-year follow-up.

RESULTS

The mean delay between either first symptoms of renal disease, or first evidence of renal failure and nephrologist referral was 10 years and 3 years 56 days, respectively. About 47% of the patients were referred less than 6 months before starting dialysis, and 27.5% less than 1 month. Blood pressure levels were higher in patients referred less than 6, 3 and 1 month (P < 0.05), as was creatinine concentration in patients referred less than 1 month (P < 0.05). In contrast, plasma calcium was lower for referral less than 6 months (P < 0.05) and 3 months (P < 0.005), as was bicarbonate concentration for referral less than 3 and 1 month (P < 0.05). Initial hospitalisation stay was prolonged (x1.5) for late referral less than 3 months (56.4 +/- 39 days vs 35.9 +/- 33.6 days, P < 0.05) as was 6 months hospitalisation length for referral less than 3 months (x1.6) (52.9 +/- 40.6 days vs 33.2 +/- 28.7 days, P < 0.05) and less than 1 month (x1.8) (61 +/- 45 days vs 33.9 +/- 28.7 days, P < 0.05) and < 1 month (x1.8) (61 +/- 45 days vs 33.9 +/- 28.7 days, P < 0.05). Only 44.1% of patients started hemodialysis with a functioning arteriovenous fistula, and patients requiring temporary access had a 4.4-fold longer initial (60.1 +/- 41.7 days vs 13.6 +/- 11.6 days, P < 0.005) and 6-month (59.6 +/- 39 days vs 13.6 (9.1, P < 0.005) hospitalisation stay. The four-year mortality rate was unaffected by the delayed referral but strongly and independently predicted by age, diabetes and hypoalbuminemia.

CONCLUSION

Early nephrologic referral and timely initiated dialysis decrease morbidity at the start of dialysis and both hospitalisation length and costs.

Unanticipated favorable effects of correcting iron deficiency in chronic hemodialysis patients

BACKGROUND

Correction of anemia in hemodialysis patients is seldom completely attained, and the response of parameters other than hemoglobin concentration to anemia correction has not been evaluated in detail.

METHODS

Laboratory parameters that suggest iron deficiency occurred in 10-15% of 206 recombinant human erythropoietin (rhEPO)-treated patients. Oral iron was given for 9 months and intravenous iron thereafter on a patient-specific basis when iron deficiency was evident. Eighty-seven hemodialysis patients with data for 12 months were followed for another 12 months. A computerized information system enabled data management and analysis.

RESULTS

With oral iron, serum ferritin decreased (P < 0.001), indicating further iron depletion. With intravenous iron, hemoglobin increased, evidence of iron deficiency decreased, and less rhEPO was needed. Striking macrocytosis appeared. Serum albumin and serum creatinine/kg body weight (an index of muscle mass) increased, while blood pressure decreased. Data were reanalyzed in four mean corpuscular volume (MCV) quartiles and two ferritin subsets at study onset. Iron deficient erythropoiesis (low MCV, mean corpuscular hemoglobin [MCH], and transferrin saturation) was striking in quartile 1; low ferritin was prevalent in all quartiles. With intravenous iron, hemoglobin increased only in quartile 1, the quartile with the greatest decrease (52%) in rhEPO dose. MCV increased in all quartiles (P < 0.001). Serum albumin increased in all MCV quartiles and both ferritin subsets, but significant creatinine/kg increase and blood pressure decrease occurred only in the low-ferritin subset.

CONCLUSIONS

Macrocytosis occurred with intravenous iron replacement. The universal MCV increase suggests unrecognized, inadequately treated, folic acid deficiency unmasked by an adequate iron supply. There was also improved well being. Effects were most clearly evident in patients with deficient iron stores.

Urea reduction ratio that considers effects of ultrafiltration and intradialytic urea generation

We modified the urea reduction ratio (URR) equation to correct the effects of ultrafiltration and intradialytic urea generation on the delivered dose of hemodialysis: mURR = [1 - (R/1 + 2*UF/BW) + 0.01*t] x 100% where mURR is modified URR, R is postdialysis plasma urea nitrogen (PUN) to predialysis PUN ratio, UF is ultrafiltrate volume in liters, BW is postdialysis body weight in kilograms, and t is dialysis session length in hours. The equation was validated against 145 hemodialysis treatments on 33 stable maintenance dialysis patients. The mURR values obtained closely predicted single-pool Kt/V (spKt/V) values. In contrast to conventional URR, the range of spKt/V values at each mURR value is narrow over a wide range of UF, t, and R values. Based on the mURR equation, mURR values of 64%, 70%, and 76% are mathematically equivalent to spKt/V levels of 1.0, 1.2, and 1.4, respectively. This equation can be a useful bedside tool to quantify hemodialysis dose.

Abnormalities of bioimpedance measures in overweight and obese hemodialyzed patients

BACKGROUND

The body composition in overweight and obese hemodialyzed patients (HD) remains ill-defined. This study evaluates in HD patients the influence of body size, as indicated by body mass index (BMI, kg/m(2)), on body composition by measuring bioimpedance analysis (BIA)-derived variables (phase angle (PA), fat-free mass (FFM) and body cell mass (BCM).

METHODS

We studied 50 Caucasian patients (mean age 62.8+/-9.2 y) on standard bicarbonate hemodialysis for at least 12 months who regularly achieved dry weight in post-HD, received similar dialysis doses and were free from inflammation/infection. Thirty-eight gender- and age-matched healthy subjects were included as controls (CON). Both HD and CON were divided into three groups on the basis of their BMI(kg/m2) 18.5-24.9, normal-weight (NW); 25-29.9, overweight (OW); and > or =30, obese (OB). In HD patients, BIA was performed 30 min after the end of dialysis.

RESULTS

Seven patients were obese (12%) while 16 were overweight (32%); in CON, 12 were obese (31%) and 12 overweight (31%). BIA-measured extracellular water was comparable in all groups. PA, which was similar in normal-weight HD and CON (6.2+/-0.9 degrees and 6.3+/-0.8 degrees ), decreased in OW- and OB-HD patients (5.3+/-1.0 degrees and 5.2+/-0.6 degrees, respectively; P<0.05 vs NW-HD) while it was unchanged in OW- and OB-CON (6.1+/-0.8 degrees and 5.9+/-0.5 degrees, P<0.05 vs respective HD groups). In OW and OB patients, the lower PA values were coupled with a major reduction of BIA-derived percentage BCM and FFM (P<0.05 vs NW-HD, and vs OW- and OB-CON). In patients, PA and BCM correlated with anthropometry-measured FFM. Of note, serum albumin and protein catabolic rate were significantly reduced in OB patients.

CONCLUSION

In overweight and obese HD patients, BIA-derived FFM, BCM and PA are significantly lower with respect to normal-weight patients and BMI-matched controls. These abnormalities of body composition are coupled with reduction of anthropometric measures of lean mass and a decrease of protein intake that, however, becomes significant only in the obese. We therefore suggest that overweight and obese HD patients are at risk of protein malnutrition in spite of excessive energy intake. BIA may be considered as a useful diagnostic tool to detect such a condition early.

Changing hemodialysis thresholds for optimal survival

BACKGROUND

The urea reduction ratio (URR), a measure quantitating solute removal during hemodialysis, is the fractional reduction of the blood urea concentration during a single hemodialysis treatment. The URR is the principal measure of hemodialysis dose in the United States. Based on studies of patients dialyzed prior to 1994, a minimum URR value of 65% was recommended to optimize survival. Because of new hemodialysis technologies and evolving demographics of the hemodialysis population, the relationship between the amount of hemodialysis and mortality was examined in contemporary cohorts.

METHODS

This retrospective cohort included> 15,000 patients per year receiving hemodialysis during 1994 through 1997. Each patient's URR was averaged for the three months prior to the beginning of each year. Mortality odds ratios were calculated for patients by URR. To determine the URR value above which no further improvement in mortality was seen ("threshold"), spline functions were tested in logistic regression models, both unadjusted and adjusted for case mix measures. The strength of fit for URR, defined by a range of candidate thresholds from 55 to 75%, was evaluated in increments of 1% for each year using spline functions.

RESULTS

The median URR was 63.2, 65.4, 67.4, and 68.1% for 1994 through 1997, respectively. The median length of hemodialysis treatments increased only six minutes from the beginning to the end of the period of analysis. Using spline functions, the threshold URR values were 61.1, 65.0, 68.0, and 71.0% for 1994 through 1997 in models adjusted for case mix. The ratio of median URR to URR threshold decreased from 1.03 in 1994 to 0.97 in 1997.

CONCLUSIONS

From 1994 to 1997, the median URR and the URR threshold for mortality benefit increased. Although an increased need in the amount of hemodialysis may be a consequence of changes in patients' demographic characteristics, the likely explanation(s) is a change in the dialysis procedure and/or blood sampling favoring higher URR values without changing the amount of dialysis provided. The recommended minimum URR of 65% appears to be too low to confer an optimal mortality benefit in the context of current practices.

How to determine ionic dialysance for the online assessment of delivered dialysis dose

BACKGROUND

Ionic dialysance may be equivalent to blood-water urea clearance corrected for recirculation (effective urea clearance); however, this is controversial. The aims of our study were (1) to verify in vivo whether the value of ionic dialysance is affected by the method of determination, given the effect of cardiopulmonary recirculation on inlet plasma water conductivity when the inlet dialysate conductivity is changed; and (2) to define the operative modalities for determining ionic dialysance to obtain an adequate estimate of effective urea clearance.

METHODS

Thirty-three hemodialysis patients were studied during 186 dialysis sessions with low-flux polysulfone dialyzers using a modified Fresenius Medical Care 4008 B machine equipped with meters to measure inlet and outlet dialysate conductivities. This machine varied inlet dialysate conductivity (Cdi) according to the following pattern: starting from baseline (step 0), Cdi was increased by 8% (step 1). After Cdi had reached the target value, which took 8 to 10 minutes, it was lowered to 8% below the baseline value (step 2). After 8 to 10 minutes, when Cdi had reached the new target, it was returned to its starting value (step 3). Four values of conventional ionic dialysance (using the standard formula) and actual ionic dialysance (taking into account cardiopulmonary recirculation) were obtained for each cycle and were compared among them and with effective urea clearance (Kde).

RESULTS

Mean conventional dialysance values at steps 0 to 2 and 2 to 3 (190 and 189 mL/min) were similar and higher than those at steps 0 to 1 and 1 to 2 (171 and 181 mL/min). Mean conventional ionic dialysance values underestimated Kde, particularly at steps 0 to 1 (-22.2 mL/min, P < 0.001) and 1 to 2 (-12.6 mL/min, P < 0.001). The actual dialysance values underestimated Kde by no more than 4.3 mL/min (P < 0.001). In steps 0 to 1 and 1 to 2, the underestimate of Kde by conventional dialysance increased at higher values of Kde, but this relationship did not exist when considering actual dialysance.

CONCLUSIONS

The value of ionic dialysance is affected by the method of determination, given the effect of cardiopulmonary recirculation on inlet plasma water conductivity when inlet dialysate conductivity is changed. As a consequence, to provide a correct and direct estimate of effective urea clearance, ionic dialysance must be determined by changing inlet dialysate conductivity in such a way as to keep inlet plasma water conductivity constant by means of two symmetrical high and low dialysate conductivity steps.

Hepatotoxic substance(s) removed by high-flux membranes enhances the positive acute phase response

BACKGROUND

Acute phase proteins (APPs) are enhanced in end-stage renal disease patients (ESRD) requiring dialysis treatment. They are involved in a variety of pathologic processes like muscle proteolysis, cachexia, regulation of appetite, and atherosclerosis. They are predictive for mortality. APPs are not only makers but also active substances. They are mainly produced in liver cells and are primarily, but not exclusively, regulated by proinflammatory cytokines. To what extent hepatic APPs are influenced by uremic toxins is still unclear. Therefore, we investigated the effects of different ultrafiltrates (UFs) on the synthesis of alpha1-acid glycoprotein (AGP) in HepG2 cells.

METHODS

A cross-sectional as well as a crossover study with high-/low-flux membranes was conducted to investigate the impact of UFs on bioactivity of liver cell cultures. Metabolic activity (MTT test), cytotoxicity (lactate dehydrogenase release), and the positive APP AGP were measured in HepG2 cells.

RESULTS

Cultured hepatocytes treated with UFs from high-flux membranes exhibited a higher cytotoxicity (18.6 +/- 0.3% high-flux vs. 13.9 +/- 0.2% low-flux, P < 0.001) and a lower metabolic activity (29.3% high-flux vs. 50.3% low-flux, P < 0.001) in comparison with low-flux UFs. In addition, enhanced APP secretion could be observed under costimulatory conditions (high-flux 5.0 +/- 0.7 vs. low-flux 3.1 +/- 0.6 ng/microg protein, P < 0.05). The effects of high- and low-flux UFs were strongly expressed at the beginning and were still significantly different after 120 minutes of hemodialysis (HD) treatment. The crossover experiments confirmed that UFs collected during high-flux HD had a higher capacity to stimulate AGP synthesis in liver cells.

CONCLUSION

The effects of UFs from dialysis patients demonstrate that hepatotoxic substances can be removed by dialysis. Stimulating the acute phase response UF collected during high-flux HD had a higher impact on liver cells in comparison with low-flux UF. These substances are putative cofactors involved in cytokine regulation.

Increased albumin and fibrinogen synthesis in hemodialysis patients with normal nutritional status

This study compared the rates of whole-body proteolysis and of albumin and fibrinogen synthesis of seven hemodialysis patients (HD) with those of seven normal matched control subjects (C). HD patients had a normal nutritional and inflammatory status and serum albumin levels >3.5 g/dl. Endogenous leucine flux, albumin and fibrinogen fractional synthesis rate (FSR), and absolute intravascular synthesis rate (ASR) of albumin and fibrinogen all were evaluated by a primed/continuous infusion of 5,5,5-D3-L-leucine. Plasma volume was determined by the Evans blue dye dilution method. Endogenous leucine flux was significantly increased in HD (2.64 +/- 0.08 micromol/kg per min) compared with C (2.17 +/- 0.07 micromol/kg per min, P: < 0.05). Serum albumin concentrations were similar in HD and C. Plasma fibrinogen levels were significantly increased in HD compared with C (P: < 0.05). Plasma volume was greater in HD than in C (P: < 0.05). As a result, total intravascular pool of both albumin (141 +/- 7 versus 114 +/- 3 g/1.73 m(2), P: < 0.05) and fibrinogen (11.7 +/- 1 versus 6.7 +/- 0.5 g/1.73 m(2), P: < 0.05) were greater in HD than in C. Albumin FSR was not statistically different in HD and C. However, albumin ASR was significantly increased in HD than in C (13.7 +/- 2 versus 10.3 +/- 1 g/1.73 m(2) per d, P: < 0.05). Similarly, FSR of fibrinogen did not differ in HD and C groups, whereas ASR of fibrinogen was significantly higher in HD than in C (3.31 +/- 0.6 versus 1.94 +/- 0.3 g/1.73 m(2) per d, P: < 0.05). In summary, normoalbuminemic HD patients have an increased intravascular pool with a greater absolute synthesis rate of both albumin and fibrinogen and an increased rate of whole-body leucine flux.

Influence of nutritional factors and hemodialysis adequacy on the survival of 1,610 French patients

Nutritional factors and dialysis adequacy are associated with outcome in hemodialyzed patients, but their relative contribution remains controversial, particularly when dialysis adequacy complies with current recommendations (Kt/V >1.2). Survival, clinical, and nutritional data from a cohort of prevalent 1,610 patients treated by hemodialysis in 20 centers in France have been collected over a 2.5-year period, from January 1996 to July 1998. Data including age, sex, cause of end-stage renal disease (ESRD), clinical outcome, time on dialysis, body mass index (BMI), blood levels of midweek predialysis albumin, prealbumin, and bicarbonate were analyzed. Normalized protein catabolic rate (nPCR), dialysis adequacy parameters, and estimation of lean body mass (LBM) from creatinine generation were computed from pre- and postdialysis urea and creatinine levels. The characteristics of the patients were as follows: age 59.6 +/- 16.5 years, 58.8% males, 11% of diabetics, time on dialysis 63.2 +/- 64.5 m. Weekly dialysis time was 12.18 +/- 1.78 hrs, Kt/V 1.34 +/- 0.34, nPCR 1.10 +/- 0.35 g/kg body weight/day. Albumin concentration was 39.4 +/- 5.3 g/L, prealbumin was 0.33 +/- 0.09 g/L, BMI was 23.0 +/- 4.5 kg/m(2). Overall survival was 89.7% +/- 0.8% and 78.4% +/- 1.1% after 1 and 2 years. In the Cox proportional hazard model, survival was significantly influenced by age, the presence of diabetes, and by concentrations of albumin and prealbumin, but not by other variables, including Kt/V and urea reduction ratio. These results indicate that nutritional protein concentrations were predictive of dialysis outcome, whereas variables reflecting actual body composition and dialysis dose were not. Furthermore, in this well-dialyzed population, dialysis adequacy had no influence on survival. In conclusion, when adequacy targets are met in hemodialyzed patients, survival is mainly dependent on age and nutritional status. Efforts should be focused on the most efficient ways to maintain nutritional status in these patients.

Adequacy of dialysis reduces the doses of recombinant erythropoietin independently from the use of biocompatible membranes in haemodialysis patients

BACKGROUND

The effect of the adequacy of dialysis on the response to recombinant human erythropoietin (rHuEpo) therapy is still incompletely understood because of many confounding factors such as iron deficiency, biocompatibility of dialysis membranes, and dialysis modality that can interfere.

METHODS

We investigated the relationship between Kt/V and the weekly dose of rHuEpo in 68 stable haemodialysis (HD) patients (age 65+/-15 years) treated with bicarbonate HD and unsubstituted cellulose membranes for 6-343 months (median 67 months). Inclusion criteria were HD for at least 6 months, subcutaneous rHuEpo for at least 4 months, transferrin saturation (TSAT) > or = 20%, serum ferritin > or = 100 ng/ml, and haematocrit (Hct) level targeted to 35% for at least 3 months. Exclusion criteria included HBsAg and HIV positivity, need for blood transfusions or evidence of blood loss in the 3 months before the study, and acute or chronic infections. Hct and haemoglobin (Hb) levels were evaluated weekly for 4 weeks; TSAT, serum ferritin, Kt/V, PCRn, serum albumin (sAlb), and weekly dose of rHuEpo were evaluated at the end of observation. No change in dialysis or therapy prescription was made during the study.

RESULTS

The results for the whole group of patients were: Hct 35 +/- 1.2%, Hb 12.1 +/- 0.6 g/dl, TSAT 29 +/- 10%, serum ferritin 204 +/- 98 ng/ml, sAlb 4.1 +/- 0.3 g/dl, Kt/V 1.33 +/-0.19, PCRn 1.11+/- 0.28 g/kg/day, weekly dose of rHuEpo 123 +/- 76 U/kg. Hct did not correlate with Kt/V, whereas rHuEpo dose and Kt/V were inversely correlated (r = -0.49; P < 0.0001). Multiple regression analysis with rHuEpo as dependent variable confirmed Kt/V as the only significant variable (P < 0.002). Division of the patients into two groups according to Kt/V (group A, Kt/V < or = 1.2; group B, Kt/V > or = 1.4), showed no differences in Hct levels between the two groups, while weekly rHuEpo dose was significantly lower in group B than in group A (group B, 86 +/- 33 U/kg; group A, 183 +/- 95 U/kg, P < 0.0001).

CONCLUSIONS

In iron-replete HD patients treated with rHuEpo in the maintenance phase, Kt/V exerts a significant sparing effect on rHuEpo requirement independent of the use of biocompatible synthetic membranes. By optimizing rHuEpo responsiveness, an adequate dialysis treatment can contribute to the reduction of the costs of rHuEpo therapy.

Patient survival among incident peritoneal dialysis and hemodialysis patients in an urban setting

We retrospectively evaluated 432 patients (336 black; 78%; and 96 white; 22%) incident to our peritoneal dialysis (PD; 195 patients; 45%) and hemodialysis (HD; 237 patients; 55%) programs from January 1987 to December 1997 who survived their first 90 days of dialysis therapy. Black patients comprised 70% of the PD and 84% of the HD patients (P: < 0.01). PD patients were more often men and younger than HD patients and less often had diabetes (40% versus 56% of HD patients; P: < 0.01) and cardiac disease (44% versus 58% of HD patients; P: < 0.01) than HD patients. Adjusting for baseline clinical and comorbid features, patient survival was determined by Cox regression analysis. Survival was better on PD therapy overall (relative risk [RR] for PD versus HD, 0.80; 1-, 2-, and 5-year survival rates, 90%, 77%, and 43% on PD versus 88%, 72%, and 35% on HD, respectively; P: = 0.21) and among black patients (RR for PD versus HD, 0.69; 1-, 2-, and 5-year survival rates, 92%, 80%, and 52% on PD versus 88%, 74%, and 40% on HD, respectively; P: = 0.09), but these were not statistically significant. The RR for PD versus HD was 1.08 for white patients (1-, 2-, and 5-year survival rates, 82%, 61%, and 23% for PD versus 82%, 62%, and 24% for HD; P: = 0.79). Significant predictors of mortality were race (RR for whites versus blacks, 1.51), age (RR, 1.03), cardiac disease (RR, 1.57), baseline albumin level (RR, 0.60), baseline serum creatinine level (RR, 0.91), baseline blood urea nitrogen level (RR, 1.01), and baseline weight (RR, 0.98). In conclusion, patient survival on dialysis therapy is significantly better for black patients and for patients entering dialysis with signs of adequate nutrition (increased weight and creatinine and albumin levels) and without evidence of cardiac disease. In an urban dialysis program, we find that adjusted patient survival on PD equals or is better than that on HD therapy, particularly among black patients, making PD a viable alternative to HD in our patient population.

Cross-sectional and longitudinal predictors of serum albumin in hemodialysis patients

BACKGROUND

Lower serum albumin concentrations predict increased mortality in hemodialysis (HD) patients. Many demographic, comorbidity, and modifiable treatment-related factors that predict HD patient outcomes may be associated with serum albumin.

METHODS

Cross-sectional predictors of baseline albumin on December 31, 1993 were sought (N = 3981). Additional effects of the same baseline predictors on subsequent trends in albumin over one year were examined in a nested subsample of patients (N = 2245). Wave-1 of the United States Renal Data System Dialysis Morbidity and Mortality special study provided the data.

RESULTS

Significant associations (P < 0.05) are summarized as older age, female gender, peripheral vascular disease, chronic obstructive pulmonary disease, and cancer predicted a lower baseline albumin and negatively influenced subsequent albumin trends. Baseline albumin was higher for blacks (vs. whites), lower for smoking and diabetes, and lower during the first year of HD treatment (<3 months and 3 to 12 months, vs.> 1 year). Trend analysis showed more positive albumin slopes for patients in their first year on HD and more negative slopes for Native Americans (vs. whites). Baseline albumin was correlated with the type of vascular access being used [arteriovenous (AV) fistulas > AV grafts > permanent catheters > temporary catheters]. Trend analysis predicted more negative albumin slopes for AV grafts and permanent catheters (vs. AV fistula access). Baseline albumin correlated inversely with bicarbonate and directly with hematocrit. Dialysis with unmodified cellulose membranes, without reuse, predicted lower baseline albumin than the other membrane-reuse categories.

CONCLUSIONS

Several exposures, which may be modifiable, were associated with serum albumin.

Characteristics and treatment of patients not reusing dialyzers in reuse units

Dialyzer reuse is practiced in more than 75% of the patients and dialysis units in the United States. However, reuse is not practiced in a small fraction of patients treated in reuse units (RUUs). This study evaluates both patient and facility characteristics associated with nonreuse in RUUs. The data source is from the Dialysis Mortality and Morbidity Study, Waves 1, 3, and 4, of the US Renal Data System. Only facilities that practiced dialyzer reuse were included in the analysis. A total of 12,094 patients from 1,095 reuse facilities were studied. Patients undergoing hemodialysis as of December 31, 1993, were selected. Of all patients treated in RUUs, 8% did not reuse dialyzers. Nonreuse was significantly (P < 0.02) more common, based on adjusted odds ratios (ORs), among patients who were younger (OR = 1.16 per 10 years younger), had primary glomerulonephritis (OR = 1.26 versus diabetes), had lower serum albumin level (OR = 1.72 per 1 g/dL lower), had more years on dialysis, and had higher level of education. Nonreuse patients were more likely to be treated with low-flux dialyzers (OR = 7.35; P < 0. 0001) and have a lower dialysis dose. No reuse was more likely in larger units and in not-for-profit and hospital-based units. Patient refusal accounted for one fourth of nonreuse in RUUs and was associated with the same factors, as well as with fewer comorbid conditions and non-Hispanic ethnicity. Significant geographic variations (up to eightfold) were documented. Nonreuse patients are treated with smaller, low-flux dialyzers and, on average, receive a lower Kt/V than reuse patients in the same units.

Delayed gastric emptying in dyspeptic chronic hemodialysis patients

Hemodialysis patients frequently experience such dyspeptic symptoms as nausea, vomiting, abdominal distension, early satiety, and anorexia. Gastroparesis might be a cause of malnutrition, and parameters of gastric emptying are inversely correlated with serum albumin levels. The aim of the present study is to determine whether delayed gastric emptying is related to dyspeptic symptoms. In 54 hemodialysis patients, a standardized history for dyspeptic symptoms was taken. In addition, gastric emptying for solids was measured in 26 patients, using the (13)C-octanoic acid breath test. There was a high prevalence of dysmotility-like dyspepsia in the hemodialyzed population. A significant difference in gastric emptying between dyspeptic hemodialysis patients and healthy volunteers and between dyspeptic and nondyspeptic hemodialysis patients was shown. There was a significant correlation between gastric emptying and dysmotility-like dyspepsia. Serum albumin level inversely correlated with gastric emptying. In conclusion, there is a high prevalence of dysmotility-like dyspepsia in hemodialysis patients. Dyspeptic patients have significantly delayed gastric emptying compared with both healthy volunteers and nondyspeptic patients.

Albumin as an outcome measure in haemodialysis in patients: the effect of variation in assay method

BACKGROUND

Serum/plasma albumin is an important predictor of future mortality/morbidity in haemodialysis (HD) patients and has been proposed as an important audit measure. Different methods of albumin assay give different results and the bias between methods may be greater in renal failure patients.

METHODS

Albumin concentration in plasma was measured by three methods, two dye-binding methods (bromocresol green (BCG) and bromocresol purple (BCP)) and an immuno-turbidimetric (ITM) method, in 143 HD patients (group I) and 49 non-renal patients (group II). Comparisons were made between means, variation in differences across a range of albumin concentrations and on the percentage of patients within the normal range.

RESULTS

In HD patients (group I), BCG over-estimated plasma albumin compared with the other two methods. The difference could be as much as 10 g/l and was more marked in hypoalbuminaemic patients. The BCP method gave results closer to the ITM method, particularly in HD patients. These differences were less marked in group II patients but both methods overestimated albumin compared with the ITM method. Using the BCG local laboratory normal range, 84% of HD patients had plasma albumin concentrations within the normal range but this fell to 57% if the BCP results were used.

CONCLUSIONS

The method for determining albumin concentration has a marked effect on the results particularly in HD patients. BCG, the most commonly used method, gives higher results than other methods and correlates poorly with an immunological method. These differences make comparative audit between nephrology units difficult and have implications for other biochemical variables and other specialties.

Fatigue in persons with renal failure who require maintenance haemodialysis

Fatigue is a highly prevalent symptom experienced by persons who live with chronic illness, including those with renal failure who require maintenance haemodialysis. Fatigue, however, is a non-specific and invisible symptom and is a phenomenon that is poorly understood by health care professionals. This study examined the symptom of fatigue as experienced by a group of 39 adult haemodialysis patients. The theory of unpleasant symptoms formed the conceptual framework for the study. A descriptive correlational design was utilized to examine fatigue from an inductive approach, considering relevant physiological, psychological and situational variables based on a review of the literature. Data were collected using a structured self-report questionnaire and biochemical data from retrospective monthly blood tests. The results of the study indicated that high levels of fatigue are experienced, with correspondingly low levels of vitality, in all the areas measured - general fatigue, physical fatigue, reduced motivation, reduced activity and mental fatigue, by adult haemodialysis patients. Individual variation was noted in the dimensions of fatigue predominantly expressed. Fatigue was significantly associated with the presence of symptoms such as sleep problems, poor physical health status and depression. No associations between fatigue and the biochemical and situational variables measured were noted. Further examination of the data revealed complex relationships between the physiological and psychological factors examined. Depression was significantly associated with physical health status, sleep problems, symptoms and anxiety. Correlations were also noted between symptoms and poor physical functioning, sleep problems and depression. Based on the results, a revised version of the theory of unpleasant symptoms relating to fatigue is presented.

Urea reduction ratio considering urea rebound

An American National Study shows that survival benefits from higher dialysis doses appear to be present up to a Kt/V level of 1.3 or a urea reduction ratio (URR) of 70%. The effect of increasing dialysis efficiency magnified urea rebound and the error in URR determinations. Several formulas have been developed to calculate URR considering the urea rebound (URRr). Smye and coworkers have proposed a method whereby the equilibrated blood urea nitrogen is predicted by additional intradialytic urea sample. Maduell and colleagues, based on analysis of postdialysis urea rebound, have proposed a method whereby the urea rebound is predicted. To compare measured URRr to estimated by Smye and Maduell formulas, 384 patients were studied, 211 males and 173 females, who received a dialysis session with their habitual parameters. Measurements of plasma urea concentration were obtained at the beginning, 90-100 min following the start of dialysis, at the end, and 45 min after dialysis. The postdialysis urea rebound was 22.4+/-9.7%. The urea kinetic model Kt/V was 1.365+/-0.26, and Kt/Vr was 1.14+/-0.23. URR was 68.7+/-6.6%, and when it was calculated with urea rebound, it decreased to 61.9+/-7.4%. The URRr correlated with calculations by Smye and Maduell formulas: 60.7+/-8.4 (r = 0.722, p < 0.001) and 61.8+/-6.6 (r = 0.933, p < 0.001), respectively. The precision of estimated limits of agreement and percentage of error by Bland and Altman analysis show that URRr estimated Maduell formula could be used in place of the URRr. Otherwise, the degree of agreement of the Smye method was not clinically acceptable. In conclusion, our results led us to suggest that in actual dialysis, the use of URR is not adequate for delivered hemodialysis dose, and URRr should be used. URRr estimated by Maduell formula could be a simple and accurate method for use in clinical practice. The recommended dialysis dose by the American National Study of URR of 70% could correspond, considering urea rebound, to Kt/Vr 1.18 or URRr of 64%.

Predictive value of functional status for mortality in patients on maintenance hemodialysis

In patients receiving maintenance hemodialysis, laboratory indices (such as serum albumin concentration) are predominantly utilized to assess well-being, while measures of functional status are rarely applied. However, the serum albumin concentration declines with advancing age, and the mean age of patients starting maintenance hemodialysis is now over 63 years. Using a 14-level modified Karnofsky activity scale, we measured baseline functional status in 522 randomly selected hemodialysis patients and prospectively monitored them for 3 years to determine the predictive value of our modified Karnofsky score for mortality. At onset of study, serum albumin and creatinine concentrations as well as hematocrit were measured and the comorbid conditions documented. At baseline, the 522 subjects (270 women and 252 men) included 327 blacks (63%), 154 whites (29%), 31 Hispanics (6%), and 10 Asians (2%) of mean age 59 +/- (SD) 15 years. The mean duration of end-stage renal disease was 4 +/- 3.6 years, and the mean serum albumin concentration was 3.7 +/- 0.4 g/dl. 166 (32%) of the patients died during the observation period. Cox regression analysis revealed inverse relations between mortality and both our modified Karnofsky score (p = 0.0001) and serum albumin concentration (p = 0.001). The predictive value of a low modified Karnofsky score for mortality persisted after analysis of subjects stratified according to serum albumin concentration (< 4 g/dl, n = 382, p = 0.0001 vs. > or = 4 g/dl, n = 140, p = 0.008). With a modified Karnofsky score (< 70 vs. > or = 70), the relative risk of death during the 3-year follow-up period was 1.44 (95% confidence interval 1.236, 1.675; p < 0.0001). Forward stepwise Cox regression analysis showed that advanced age (p = 0.0005), white race (p = 0.0009), diabetes mellitus (p = 0.01), and a low serum albumin concentration (p = 0.003) were independently associated with an increased risk of mortality during follow-up after adjustment for other factors. A modified Karnofsky score (p = 0.14) did not predict survival in the Cox model when other independent variables were included. We conclude that in patients with end-stage renal disease sustained on maintenance hemodialysis, a poor functional status (measured on a modified Karnofsky activity scale) is associated with early mortality. Periodic measurement of modified Karnofsky score is a simple, low-cost, and reliable means of identifying patients on dialysis at risk for early death.

Design and statistical issues of the hemodialysis (HEMO) study

The Hemodialysis Study is a multicenter clinical trial of hemodialysis prescriptions for patients with end stage renal disease. Participants from over 65 dialysis facilities associated with 15 clinical centers in the United States are randomized in a 2 x 2 factorial design to dialysis prescriptions targeted to a standard dose or a high dose, and to either low or high flux membranes. The primary outcome variable is mortality; major secondary outcomes are defined based on hospitalizations due to cardiovascular or infectious complications, and on the decline of serum albumin. The Outcome Committee, consisting of study investigators, uses a blinded review system to classify causes of death and hospitalizations related to the major secondary outcomes. The dialysis dose intervention is directed by the Data Coordinating Center using urea kinetic modeling programs that analyze results from dialysis treatments to monitor adherence to the study targets, adjust suggested dialysis prescriptions, and assist in trouble-shooting problems with the delivery of dialysis. The study design has adequate power to detect reductions in mortality rate equal to 25% of the projected baseline mortality rate for both of the interventions.

Adequacy of peritoneal dialysis

The National Kidney Foundation-Dialysis Outcomes Quality Initiatives guidelines have standardized many aspects of treating end-stage renal disease patients with peritoneal dialysis in an attempt to improve overall patient outcome. While recommending certain total solute clearance goals, the guidelines have also pointed out deficiencies in our knowledge base and precipitated many controversies. Some of these controversies have been resolved while others may have been interpreted wrongly, unnecessarily resulting in transfer of patients from peritoneal dialysis to hemodialysis due to "failure to meet adequacy targets" even when doing well clinically. This report reviews the rationale for the original guidelines and their subsequent modification. It also outlines a rational approach toward prescription modification based on peritoneal physiology. Specific solute clearance target goals discussed are the modifications for continuous ambulatory peritoneal dialysis (CAPD) and cycler peritoneal dialysis (CCPD), and a review of what solute clearance targets subsequent guidelines from other countries have used. Some examples are as follows: new guidelines suggest that solute clearance goals for creatine clearance should differ for low and low-average transporters than for high and high-average transporters (weekly clearance of 50 and 60 1/1.73 m(2), respectively) while Kt/V targets remain unchanged. Also discussed is the rationale for having the same target for patients on CCPD with a mid-day exchange as those for patients on CAPD. We are also reminded that solute clearance is only one aspect of "adequate" dialysis-blood pressure and volume control are equally important, and ways to maintain euvolemia and blood pressure control are discussed in the context of prescription management.

Mortality caused by sepsis in patients with end-stage renal disease compared with the general population

BACKGROUND

In the United States, infection is second to cardiovascular disease as the leading cause of death in patients with end-stage renal disease (ESRD), and septicemia accounts for more than 75% of this category. This increased susceptibility to infections is partly due to uremia, old age, and comorbid conditions. Although it is intuitive to believe that mortality caused by sepsis may be higher in patients with ESRD compared with the general population (GP), no such data are currently available.

METHODS

We compared annual mortality rates caused by sepsis in patients with ESRD (U.S. Health Care Financing Administration 2746 death notification form) with those in the GP (death certificate). Data were abstracted from the U.S. Renal Data System (1994 through 1996 Special Data request) and the National Center for Health Statistics. Data were stratified by age, gender, race, and diabetes mellitus (DM). Sensitivity analyses were performed to account for potential limitations of the data sources.

RESULTS

Overall, the annual percentage mortality secondary to sepsis was approximately 100- to 300-fold higher in dialysis patients and 20-fold higher in renal transplant recipients (RTRs) compared with the GP. Mortality caused by sepsis was higher among diabetic patients across all populations. After stratification for age, differences between groups decreased but retained their magnitude. These findings remained robust despite a wide range of sensitivity analyses. Indeed, mortality secondary to sepsis remained approximately 50-fold higher in dialysis patients compared with the GP, using multiple cause-of-death analyses; was approximately 50-fold higher in diabetic patients with ESRD compared with diabetic patients in the GP, when accounting for underreporting of DM on death certificates in the GP; and was approximately 30-fold higher in RTRs compared with the GP, when accounting for the incomplete ascertainment of cause of death among RTRs. Furthermore, despite assignment of primary cause-of-death to major organ infections in the GP, annual mortality secondary to sepsis remained 30- to 45-fold higher in the dialysis population.

CONCLUSIONS

Patients with ESRD treated by dialysis have higher annual mortality rates caused by sepsis compared with the GP, even after stratification for age, race, and DM. Consequently, this patient population should be considered at high-risk for the development of lethal sepsis.

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.

Analysis of patients dying within one year of starting renal replacement therapy

BACKGROUND

The annual gross mortality of end-stage renal failure patients remains very high (approximately 15-20%) leading some to question the wisdom of accepting patients with limited prognosis for dialysis. We have reviewed the demographic and clinical characteristics of patients who died within a year of commencing renal replacement therapy (RRT) over a 5-year period to establish whether these patients could be identified at the start of therapy.

METHODS

Case notes of patients who died within 1 year of commencing RRT between 1st April, 1991 and 31st March, 1996 were reviewed. Comorbidity at the start of dialysis was used to classify patients into high-, medium- and low-risk groups using two published scales to determine whether either graded a high proportion of deaths as high risk. Factors such as age, social circumstances, cause of death, renal diagnosis and mode of dialysis were also analysed.

RESULTS

17.5% of patients commencing RRT died in the first year. Not all of these patients could be identified as high risk by comorbidity assessment at dialysis initiation - 50% of patients who died were classified by one scale as medium risk. Age did not clearly predict outcome, as 42% of patients who died were less than 65 years old.

CONCLUSION

These data suggest that it is difficult to use current risk stratifications to accurately predict outcome on RRT.

Racial differences in survival of patients on dialysis

BACKGROUND

Recent studies have documented racial differences in the crude mortality rates of patients on dialysis. However, proper interpretation of these findings requires adjustment for potential confounders and comorbid risk factors between the racial groups.

METHODS

We examined the clinical data on 3752 Caucasian patients, 451 Southeast Asian patients, 322 South Asian patients, and 319 black patients who were treated with hemodialysis or peritoneal dialysis under a Universal Health Care system in Toronto and prospectively followed between 1981 and 1995. In all patients, a number of comorbid risk factors for survival was assessed at the start of dialysis and was reassessed with their outcome status (that is, continued dialysis, transplantation, death, or loss to follow-up) at least every six months. Cox proportional hazards analysis was used to fit multivariate models predicting patient survival. Pairwise comparisons of the relative hazards of death between the racial groups were performed after stratifying for cardiovascular disease, diabetes mellitus, and hypertension at the start of dialysis, and were adjusted for differences in other comorbid risk factors.

RESULTS

The risk of death in Caucasian patients was significantly increased when compared with Southeast Asian patients, South Asian patients, and black patients [multivariate relative hazards (95% CI): 1.63 (1.36 to 1.97), 1.36 (1.07 to 1.73), 1.34 (1.07 to 1.67), respectively]. Additionally, we detected an interaction between race and cigarette smoking (P < 0. 004), suggesting that in the dialysis patients who smoked, whites had a higher mortality risk compared with non-whites.

CONCLUSIONS

Differences in patient survival on dialysis exist between racial groups. However, the genetic and environmental determinants that underlie these differences are presently unknown.

Delivered dialysis dose is suboptimal in hospitalized patients

Underdialyzed patients have high hospitalization and mortality rates. It is unclear if such patients receive adequate dialysis during hospitalization. In this cross-sectional study, we evaluated single treatment delivered dialysis dose during hospitalization and compared this to the dosage received at the free-standing outpatient clinics in the same patients. Eighty-four patients (54% male) aged 23-63 years (means +/- SD 55.5 +/- 14.6) who have been on dialysis for at least 3 months were evaluated. Hypertension and diabetes were the most common diagnoses, while thrombosed graft or fistula accounted for 40% of admissions. The mean dialysis treatment time (Td) was 30 min longer in the outpatient (OP) setting than the hospital (H): 3.6 +/- 0.3 vs. 3.1 +/- 0.2 h (p < 0.0001). Attained blood flow (QB) was 15% greater in the OP than H: 394 +/- 40 vs. 331 +/- 54 ml/min (p < 0.0001). The Kt/V was analyzed in 49 of 84 patients; the OP Kt/V was 20% greater than the H Kt/V: 1.38 +/- 0.2 vs. 1.11 +/- 0.1 (p < 0.0001). A further breakdown of H Kt/V according to access and membrane types showed that patients with functional grafts/fistula had a higher Kt/V than those with temporary accesses 1.14 +/- 0.1 vs. 1.07 +/- 0.1 (p = 0.01). We conclude that hospitalized patients receive suboptimal dialysis dose, this could have a negative impact on survival if hospitalization is recurrent and prolonged. Kinetic modeling should be routinely performed in such patients and Td should be increased in patients with temporary accesses.

Study of effect of optimization of dialysis and protein intake on neuromuscular function in patients under maintenance hemodialysis treatment

This study was carried out on 22 patients on maintenance hemodialysis. Among them, 20 patients were males and 2 were females, their age ranged from 12 to 50 years. Initially, the patients were assessed clinically and by laboratory investigations and their dialysis was assessed by studying their urea kinetic modeling following the nomographic approach for calculating their Kt/V values. Their nutrition was assessed by measuring skin folds, midarm circumference, laboratory parameters and by calculating the normalized protein catabolic rate (nPCR). Also their neuromuscular functions were assessed by clinical examination and neurophysiologic study. Dialysis dose was readjusted to achieve a target Kt/V value of 1.3 for patients on 3 times weekly dialysis and 1.6 for patients on twice weekly dialysis. Also, their nutrition was reviewed to achieve nPCR 1.2 g/kg/day and caloric intake 30-40 kcal/kg/day through diet manipulation and support. The patients were assessed finally after 3 months on targeted dialysis and nutrition by thorough clinical, laboratory and neuromuscular assessment. Analysis of neurophysiologic data showed significant improvement in electromyography. Furthermore, fatigue test showed significant (p = 0.002) decreases in muscle fatigue after optimization of dialysis dose and patients' nutrition. From this study, we may conclude that in dialysis patients, even when asymptomatic and clinically stable, neurologic deficits do exist and using area kinetic modeling to improve dialysis and patients' nutrition is valuable in improving their neuromuscular functions.

The removal of uremic toxins

Three major groups of uremic solutes can be characterized: the small water-soluble compounds, the middle molecules, and the protein-bound compounds. Whereas small water-soluble compounds are quite easily removed by conventional hemodialysis, this is not the case for many other molecules with different physicochemical characteristics. Continuous ambulatory peritoneal dialysis (CAPD) is often characterized by better removal of those compounds. Urea and creatinine are small water-soluble compounds and the most current markers of retention and removal, but they do not exert much toxicity. This is also the case for many other small water-soluble compounds. Removal pattern by dialysis of urea and creatinine is markedly different from that of many other uremic solutes with proven toxicity. Whereas middle molecules are removed better by dialyzers containing membranes with a larger pore size, it is not clear whether this removal is sufficient to prevent the related complications. Larger pore size has virtually no effect on the removal of protein-bound toxins. Therefore, at present, the current dialytic methods do not offer many possibilities to remove protein-bound compounds. Nutritional and environmental factors as well as the residual renal function may influence the concentration of uremic toxins in the body fluids.

Nutritional aspects in hemodialysis

The results of cross sectional studies throughout the world indicate that maintenance hemodialysis patients are at risk of malnutrition. Longitudinal studies show that malnutrition is associated with a reduced life expectancy mainly because of cardiovascular and infectious complications. Several factors are responsible for malnutrition of hemodialysis patients. Protein-energy intake is often reduced because of inappropriate dietary restrictions, anorexia, and taste alterations, promoting malnutrition in most patients entering dialysis. Intercurrent illnesses and frequent hospitalizations add to meal disturbances. A state of persistent catabolism may result from acidosis, resistance to anabolic factors such as growth hormone, insulin, and insulin-like growth factor-1, as well as a chronic inflammatory state caused by dialysis membrane and fluid bioincompatibility. In addition, losses of nutrients, including glucose, amino acids, proteins, and vitamins, occur during the dialysis treatment. Careful monitoring of dietary intakes is mandatory even in predialysis patients. In hemodialysis patients, the dose of dialysis should be adapted to correct acidosis and to relieve anorexia caused by accumulation of uremic toxins and hyperleptinemia. When malnutrition is established, active therapeutic interventions should take place, including intradialytic parenteral nutrition if oral supplementation has failed to improve nutritional status. Anabolism has been observed during the administration of recombinant growth hormone and insulin-like growth factor-1. Emerging therapeutic strategies against malnutrition may also involve a short period of daily dialysis.

Outcome data on pediatric dialysis patients from the end-stage renal disease clinical indicators project

Network 1 (New England) initiated the Clinical Indicator Project to survey dialysis adequacy (Kt/V), nutrition (serum albumin level), and anemia management in patients maintained on chronic dialysis. Because little information is available in children, data were specifically recorded covering these variables in patients (age, 1 to 18 years) maintained on either hemodialysis (HD) or peritoneal dialysis (PD). During the 18 months of data collection, 29 observations were recorded on 23 HD patients (age, 14.3 +/- 3.6 years), and 43 observations were made on 30 PD patients (age,10.6 +/- 4.7 years). Kt/V correlated inversely with the age of the patient (HD, P < 0.004; PD, P < 0.0007). Although serum albumin level was not associated with dialysis adequacy in HD patients, there was a strong inverse relationship between albumin level and Kt/V in PD patients (P < 0.002). Hematocrit values were not significantly different in the two groups (HD, 31.0% +/- 5.5% versus PD, 32.9% +/- 4.8%) and could not be correlated with weekly erythropoietin dose. Weekly erythropoietin dose was directly related to patient age in both groups (HD, P < 0.05; PD, P < 0.02). The weekly erythropoietin dosage needed to maintain the hematocrit was greater in HD patients (HD, 11,211 +/- 7,484 U versus PD, 3,790 +/- 1,968 U; P < 0.0001). We conclude that (1) smaller children in both groups tend to have a greater Kt/V, (2) Kt/V greater than 2.75 in PD patients may not improve nutrition per se and could result in increased albumin losses, and (3) erythropoietin dosing appears to correlate best with patient size (age) rather than degree of anemia.

Vitamin D deficiency is implicated in reduced serum albumin concentrations in patients with end-stage renal disease

The mortality rate in hemodialysis patients remains extremely high, and reduced serum albumin concentration resulting from malnutrition is the strongest predictor of mortality and morbidity. Several inflammatory cytokines involved in malnutrition, including interleukin-1, interleukin-6, and tumor necrosis factor-alpha, are modulated by 1,25-dihydroxyvitamin D(3) [1,25-(OH)(2)D(3)], of which synthesis is impaired in end-stage renal disease. We evaluated whether 1,25-(OH)(2)D(3) deficiency might be involved in reduced serum albumin concentrations. Fifty-one predialysis uremic patients about to begin hemodialysis therapy were divided into groups with serum 1,25-(OH)(2)D(3) concentrations less than 18 pg/mL (low-D(3) group; n = 39) and concentrations of 18 pg/mL or greater (normal-D(3) group; n = 12). Serum albumin concentrations before the initiation of hemodialysis treatment were compared between the two groups. Furthermore, the effect of supplementation with active forms of vitamin D during 4 months of hemodialysis treatment on serum albumin concentrations was retrospectively evaluated in the low-D(3) group. Serum albumin concentrations in the low-D(3) group were significantly less than those in the normal-D(3) group (3.58 +/- 0. 50 versus 3.82 +/- 0.10 g/dL; P = 0.034). Considering all patients, a significant positive correlation between serum concentrations of albumin and 1,25-(OH)(2)D(3) was noted (r = 0.417; P = 0.0023). Supplementation with active forms of vitamin D significantly increased serum albumin concentrations in the low-D(3) group from 3. 61 +/- 0.12 to 3.79 +/- 0.13 g/dL (P = 0.0067). These findings indicate that reductions in serum albumin concentrations may be attributed, at least in part, to vitamin D deficiency in patients with end-stage renal disease.

Whither goest Kt/V?

Uremia is characterized by gross contamination of body water with a wide spectrum of retained solutes normally excreted by the kidney. The rationale for dialysis therapy is that these retained solutes have concentration-dependent toxicity, which can be ameliorated through removal by dialysis. Apart from the well-established clinical consequences of abnormalities in fluid, electrolyte, acid base metabolism, and retained beta 2-microglobulin (beta 2 m), there is very little understanding of solute-specific uremic toxicity. Evidence is reviewed to demonstrate the following: (1) Many aspects of the uremic syndrome are controlled by adequate dialysis of low molecular weight solutes. (2) Urea can serve as a generic molecule to quantitate the fractional clearance of body water by dialysis (Kt/V) of retained low molecular weight solutes. (3) Urea has no concentration-dependent toxicity, and the generation rate of putative toxic low molecular weight solutes is not proportional to urea generation. The major clinical consequences and controversies stemming from these interrelationships are reviewed. Kinetic approaches to determine Kt/V dose equivalency between intermittent and continuous dialysis therapy are reviewed. We conclude that Kt/V can and will be generalized to describe the kinetics of other solutes such as beta2m as our knowledge of uremic toxicity grows, and hence, it is predicted that it will goeth and goeth and goeth.

Assessing residual renal function and efficiency of hemodialysis--an application for urographic contrast media

BACKGROUND

In patients on hemodialysis with end-stage renal disease there is an increasing interest in measuring both residual renal function (RRF) and quantity and quality of dialysis because insufficient dialysis gives higher mortality. For that purpose we have measured clearances of two urographic iodine (I) contrast media (CM) with different molecular masses (iohexol 821 u and iodixanol 1, 550 u). These CM are filtered through glomeruli and dialysis membranes and have higher molecular masses than urea and creatinine and might represent the dialyzability of the hypothetic uremic toxins with a molecular mass of 300-5,000 u.

METHODS

Thirteen patients (8 of them were anuric) immediately after hemodialysis received 15 ml iohexol (300 mg I/ml i.v.) and 2 weeks later in the same way 15 ml iodixanol (320 mg I/ml). Nine other patients (2 anuric) received CM after only one dialysis; 8 got iohexol and 1 got iodixanol. After the CM injections the iodine concentrations were measured with X-ray fluorescence in blood and, when available, urine during the following 2 days including both the start and end of the next dialysis. Eighteen patients after two dialysis sessions, 2 weeks apart, received 10 ml iohexol i.v., and a single blood sample was taken at the start of the next dialysis 2 days later to determine RRF alone.

RESULTS

In the 10 anuric patients the extrarenal clearances (mean +/- SD) were 2.5 +/- 1.1 and 2.7 +/- 1.1 ml/min/1.73 m(2) for iohexol and iodixanol, respectively. In patients with RRF good correlations were demonstrated between body clearance, based on two blood samples, and renal clearance of CM. Good correlations (r(2) = 0.853 for iohexol, r(2) = 0.933 for iodixanol) were noted between two-sample and single-sample body clearances. Repeated single sample iohexol clearances gave a coefficient of variation of 15%. During dialysis the clearances of iohexol and iodixanol were, respectively, 69 +/- 16 and 58 +/- 11 ml/min/1.73 m(2) when calculated from a single-pool model (hemodialysis clearance of CM from plasma). A median increase (rebound) of CM concentrations in plasma 45 min dialysis was 8% for iodixanol and 18% for iohexol. When the CM concentration 45 min after dialysis was used, the clearance values were by 8-10% lower and represented the hemodialysis clearance of CM from the extracellular compartments. The dialysis eliminations of iohexol and iodixanol were similar to that of urea, measured as percentage reduction of serum levels during dialysis.

CONCLUSIONS

A single injection of CM at the end of dialysis followed by a single blood sample at the start of the next dialysis gives total body clearance, i.e., an estimation of the RRF. An additional blood sample at the end of the next dialysis gives dialysis efficiency.

Dyadic relationship conflict, gender, and mortality in urban hemodialysis patients

The effects of dyadic satisfaction and conflict have not been well defined in the hemodialysis (HD) population. The aim of this study was to determine whether the perception of decreased dyadic satisfaction was associated with mortality in patients treated with HD, and if so, whether there were different relationships between risk factors, and differential outcomes in men and women. A total of 174 HD patients, primarily African-Americans, involved in dyadic relationships for more than 6 mo had indices of dyadic satisfaction, depression, perception of illness effects, social support, behavioral compliance with the dialysis prescription, and plasma interleukin-1 (IL-1) and beta-endorphin levels measured. Cox proportional hazards models assessed relative mortality risks. Patients' dyadic satisfaction scores correlated with beta-endorphin levels. There was no correlation of IL-1 or beta-endorphin with any psychosocial or behavioral compliance measure in the group as a whole. Correlations between psychosocial, medical, and neuroimmunologic variables were different in men and women. For women, dyadic satisfaction correlated with beta-endorphin levels, depression, and perception of illness. Women with higher dyadic satisfaction and decreased dyadic conflict were at decreased mortality risk, but dyadic adjustment indices were unassociated with differential survival in the larger group of men. Correlations between neuroendocrine and immune markers are different in African-American male and female HD patients. Greater dyadic satisfaction and lower dyadic conflict are independently associated with decreased mortality in female African-American HD patients, of the same order of magnitude as medical risk factors. Such effects may be attributable to a relationship between dyadic satisfaction and conflict and health-related behaviors, or through an effect on neuroendocrine or immunologic status.

Peritoneal dialysis adequacy and risk of death

BACKGROUND

The purpose of this study was to evaluate the relationship between dialysis dose, patient characteristics, and medical comorbidities on mortality in chronic peritoneal dialysis patients.

METHODS

This work comprised a study cohort of 1446 patients obtained from a random sample of chronic peritoneal dialysis patients from each dialysis center in three southeastern states. Data collected on a standardized form were used to calculate weekly Kt/V urea and creatinine clearance. Data were linked to Network files containing data on patient demographic and medical comorbidities.

RESULTS

Both weekly Kt/V urea and creatinine clearance were measured at least once in only 60.5% of continuous ambulatory peritoneal dialysis (CAPD) patients and 63.7% of cycler patients. Among the 873 patients who had at least one calculable adequacy measure, the mean (+/-SD) weekly Kt/V urea was 2.13 +/- 0.55, and the normalized mean weekly creatinine clearance was 62.9 +/- 20.4 L/week/m2. During the seven month period of follow-up, there were 140 deaths. In separate logistic regression models that included all of the studied risk factors, using separate variables for the urinary and peritoneal components of dialysis adequacy, each 10 L/week/1.73 m2 increase in the urinary component of weekly creatinine clearance was associated with a 40% decreased risk of death, and each 0.1 unit increase in the urinary component of weekly Kt/V urea was associated with a 12% decreased risk of death. In contrast, the dialysate components of neither weekly creatinine clearance nor weekly Kt/V urea were predictive of death. Other factors that were associated with an increased risk of death included increasing age, diabetes mellitus as the cause of end-stage renal disease (ESRD), and a history of myocardial infarction.

CONCLUSIONS

Residual renal function, as expressed by weekly creatinine clearance or Kt/V urea, is an important predictor of death in chronic peritoneal dialysis patients. The nonsignificant findings regarding peritoneal clearances and mortality may possibly be secondary to the narrow range of peritoneal clearances in this study cohort.

Insulin-like growth factor I correlates with protein intake estimated from the normalized protein catabolic rate in hemodialysis patients

BACKGROUND/AIM

Malnutrition and catabolism are predominant problems in patients undergoing hemodialysis. The aim of this study was to clarify the relationship between insulin-like growth factor I (IGF-I), the serum levels of which are influenced by nutrition and which by itself promotes amino acid uptake, and insulin-like growth factor binding protein 1 (IGFBP-1), known to regulate serum (s) IGF-I and protein intake, in end-stage renal disease patients.

METHODS

Thirty hemodialysis patients were studied, and s-IGF-I and s-IGFBP-1 levels were measured by radioimmunoassay. The s-IGF-I method used was validated according to a reference method. The s-IGF-I standard deviation (SD) score was calculated, giving the individual deviation from the mean of a reference population. The protein intake was estimated both directly by 3-day food recall by a dietician and indirectly by normalized protein catabolic rate (PCRn).

RESULTS

The mean serum IGF-I level was 166 +/- 10 microgr;g/l, corresponding to a normal s-IGF-I SD score (0.5 +/- 0.3). S-IGFBP-1 was elevated threefold to 101 +/- 11 microg/l as compared with normal subjects. The s-albumin was 39.9 +/- 0.5 g/l and the s-bicarbonate 24 +/- 0.4 mmol/l. There were significant correlations between s-IGF-I SD score or s-IGF-I (log-transformed) and PCRn (r = 0.37, p < 0.004, and r = 0.41, p < 0.001, respectively). The s-IGF-I/s-IGFBP-1 ratio was also positively correlated with PCRn (r(s) = 0.36, p < 0.007, by Spearman's rank correlation). The s-albumin was inversely correlated with log s-IGFBP-1 (r = -0.38, p < 0.01) and positively with the s-IGF-I/s-IGFBP-1 ratio (r = 0.36, p < 0.007) but not with s-IGF-I (p < 0.13). Serum total cholesterol, triglycerides, and total body fat as percentage of body weight correlated with s-IGF-I (r = 0.47, p < 0.004, r = 0.45, p < 0.01, and r = 0.42, p < 0.004, respectively) as well as with the s-IGF-I SD score. No correlations were seen between s-IGF-I and protein or caloric intake by direct estimates from dietary food recalls.

CONCLUSIONS

The s-IGF-I and the s-IGF-I/s-IGFBP-1 ratio were correlated with estimates of protein intake of the patients calculated from urea kinetics (PCRn) but not with direct estimates by the dietitian. The s-IGF-I SD score and the ratio s-IGF-I/s-IGFBP-1 might be a tool to monitor anabolic status and to select hemodialysis patients for therapeutic intervention with recombinant human IGF-I and/or recombinant human growth hormone to counteract catabolism.

Randomized double-blind trial of oral essential amino acids for dialysis-associated hypoalbuminemia

BACKGROUND

Hypoalbuminemia is associated with substantial morbidity and mortality in dialysis patients.

METHODS

Subjects with a mean three-month prestudy serum albumin of 3.8 g/dL or less and who demonstrated >/=90% compliance during a two-week run-in period were randomized to 3.6 g of essential amino acids (EAAs) or placebo three times daily with meals for three months. Randomization was stratified by dialysis modality and by severity of the hypoalbuminemia. The primary study outcome was change in the average of three monthly serum albumin measurements between baseline and follow-up.

RESULTS

Fifty-two patients were randomized; 47 patients (29 hemodialysis and 18 peritoneal dialysis) met the predetermined primary analysis criteria. The mean compliance rates averaged 75, 70, and 50% at months 1, 2, and 3, respectively, and were similar for EAAs and placebo. Serum albumin in the hemodialysis patients, EAA versus placebo, improved [(mean +/- SE) 0.22 +/- 0.09 g/dL, P = 0.02]. Changes in peritoneal dialysis patients were not significant (0.01 +/- 0.15 g/dL), but approached significance for the total study group (0.14 +/- 0.08 g/dL, P = 0.08). Patients in the very low albumin strata (<3.5 g/dL) improved more than those in the low albumin strata (3.5 to 3.8 g/dL, P < 0.01). There was a significant correlation (r = 0.83, P = 0.001) within the hemodialysis EAA group between the baseline C-reactive protein level and improvement in serum albumin. Improvements were also seen in grip strength and SF-12 mental health score, but not in serum amino acid levels, SF-12 physical health score, or anthropometric measurements.

CONCLUSIONS

Oral EAAs induce a significant improvement in the serum albumin concentration in hemodialysis but not peritoneal dialysis subjects. Further study of their long-term effects on morbidity and mortality is warranted.