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

Impact of hypertension on cardiomyopathy, morbidity and mortality in end-stage renal disease

A cohort of 432 ESRD (261 hemodialysis and 171 peritoneal dialysis) patients was followed prospectively for an average of 41 months. Baseline and annual demographic, clinical and echocardiographic assessments were performed, as well as serial clinical and laboratory tests measured monthly while on dialysis therapy. The average mean arterial blood pressure level during dialysis therapy was 101 +/- 11 mm Hg. After adjusting for age, diabetes and ischemic heart disease, as well as hemoglobin and serum albumin levels measured serially, each 10 mm Hg rise in mean arterial blood pressure was independently associated with: the presence of concentric LV hypertrophy (OR 1.48, P = 0.02), the change in LV mass index (beta = 5.4 g/m2, P = 0.027) and cavity volume (beta = 4.3 ml/m2, P = 0.048) on follow-up echocardiography, the development of de novo cardiac failure (RR 1.44, P = 0.007), and the development of de novo ischemic heart disease (RR 1.39, P = 0.05). The association with LV dilation was of borderline statistical significance (OR 1.48, P = 0.06). Mean arterial blood pressures greater than 106 mm Hg were associated with both echocardiographic and clinical endpoints. Paradoxically, low mean arterial blood pressure (RR 1.36 per 10 mm Hg fall, P = 0.009) was independently associated with mortality. The association of low blood pressure with mortality was a marker for having had cardiac failure prior to death. We conclude that even moderate hypertension worsens the echocardiographic and clinical outcome in ESRD patients, especially in those without previous clinical cardiac disease.

Comparison of methods for measuring albumin in peritoneal dialysis and hemodialysis patients

Serum albumin levels have been used extensively as an indicator of morbidity in patients with end-stage renal disease. Recent evidence suggests that albumin levels vary considerably in hemodialysis patients depending on the laboratory method used, but formulas for comparing albumin values by different methods have not been developed. We prospectively evaluated the effects of measuring albumin by three different methods on paired plasma and serum from 23 patients on continuous ambulatory peritoneal dialysis (CAPD) and 53 patients on chronic maintenance hemodialysis. Plasma and serum gave virtually identical results independent of method used. In CAPD patients, bromcresol green and nephelometry gave nearly identical albumin measurements through the entire range of plasma levels. In contrast, bromcresol purple gave values that were 9.9 percent +/- 1.3 percent lower (P < 0.05). Hemodialysis patients showed a similar pattern with close agreement between bromcresol green and nephelometry, but bromcresol purple gave lower albumin levels by 19.1 percent +/- 1.2 percent (P < 0.05). The discrepancy in albumin in CAPD patients was significantly less than in the hemodialysis patients (P < 0.05), suggesting that there were fewer interfering substances in the blood of CAPD patients than in hemodialysis patients. Linear regression analysis was used to develop simple formulas for comparing albumin values obtained by the different methods in CAPD and hemodialysis patients. These studies show that values for albumin in blood vary significantly by method of analysis in CAPD and hemodialysis patients. By the use of these formulas, it becomes possible to compare albumin values between centers using different methods for the purpose of quality management.

Nonrespiratory predictor of mechanical ventilation dependency in intensive care unit patients

OBJECTIVE

To determine the role of serum albumin concentration as a predictor of mechanical ventilation dependency.

DESIGN

Prospective, observation trial.

SETTING

Multidisciplinary intensive care unit (ICU) in a university hospital.

PATIENTS

One hundred forty-five consecutive patients who required mechanical ventilation for > 72 hrs.

INTERVENTIONS

Patients were classified into five different groups based on the cause of respiratory failure. The following parameters were recorded daily: serum albumin concentration; Acute Physiology and Chronic Health Evaluation II (APACHE II) score; and fluid balance. Using multiple regression, multiple logistic regression analysis, and the Anderson-Gill proportional hazards model, we determined the metabolic factors that could help predict weaning success.

MEASUREMENTS AND MAIN RESULTS

The mean length of ICU stay was 12.3 +/- 1.0 days. The duration of mechanical ventilation dependency was 10.5 +/- 1.0 days. The initial mean serum albumin concentration was 25.2 +/- 0.6 g/L. The APACHE II score on the first day of ICU stay was 19.1 +/- 0.6. Although albumin concentration was significantly lower and the APACHE II score was significantly higher in ICU nonsurvivors than in ICU survivors, albumin concentration on ICU admission was not a predictor of the length of time spent receiving mechanical ventilation. The profile of albumin concentration changes was different between weaned and mechanical ventilation-dependent patients. At the time of weaning patients from the ventilator, the median albumin concentration was higher than in those patients who continued to be supported by mechanical ventilation. This effect of albumin could not be attributed to patient fluid balance or to the severity of illness since each factor had an independent influence in predicting weaning, using the Anderson-Gill proportional hazards models.

CONCLUSIONS

Initial serum albumin concentration did not necessarily predict weaning success. However, when serum albumin concentration was assessed on a daily basis, its trend was important in determining the relative chance of being successfully weaned from the ventilator. This finding suggests that albumin may be an index of the metabolic status of the patient, which could be important in determining the weanability of the patients who are mechanically ventilated for prolonged periods of time.

Effect of access recirculation on the modeled urea distribution volume

The effect of vascular access recirculation (AR) on the modeled urea distribution volume (V) is not straightforward. When blood is sampled properly so that it is not admixed with recirculated blood, AR will cause an unexplained increase in V in cases in which AR is present throughout the dialysis session (when AR is limited to the terminal portion of a dialysis session it will cause little or no change in the modeled V). On the other hand, when blood is sampled from the arterial line after simply stopping the pump, postdialysis blood urea nitrogen (BUN) represents arterial line BUN and does not always reflect the BUN in the patient's blood. Under these conditions, when AR is present throughout the dialysis session the modeled V usually shows an unexplained decrease, but V may be unchanged, depending on the urea reduction ratio (URR). We performed a mathematical analysis to predict when V would be decreased and when it would be unchanged when the postdialysis BUN is contaminated with admixed blood. The analysis revealed that when AR is present uniformly throughout the dialysis session, the modeled V should be underestimated when the URR is < or = O.70. When the URR is greater than 0.70, even severe degrees of AR may not be reflected by a change in V. When AR is limited to the terminal part of the dialysis session or when AR increases during the dialysis session, and when V is based on admixed postdialysis blood, underestimation of V will occur in almost all circumstances. In a cross-sectional comparison of modeled to anthropometric volume ratios in eight patients with severe AR and in 11 controls, and in sequential modeling studies in a single patient in whom severe AR developed gradually over time, the volume ratio was low in most, but not all instances when modeled V was based on an admixed postdialysis BUN sample.

Effects of increasing dialysis dose on serum albumin and mortality in hemodialysis patients

Dialysis dose and malnutrition have a great impact on the clinical out come of chronic hemodialysis patients. The interrelationships between them, however, remain undefined. Thus, we performed a study to determine the effects of increasing the dialysis dose on serum albumin concentrations and mortality in hemodialysis patients. We examined urea kinetic modeling, biochemical nutritional indices, comorbid conditions, patient survival time, and annual mortality rate. Dialysis dose, measured by Kt/V, significantly increased from 1.3 +/- 0.3 in 1987 to 1.5 +/- 0.4 in 1990 and to 1.7 +/- 0.4 in 1993. Serum albumin level also increased from 3.8 +/- 0.4 g/dL in 1987 to 4.0 +/- 0.4 in 1990 and to 1.7 +/- 0.4 in 1993. In 1993, 76% of patients had Kt/V > or = 1.50 compared with 45% in 1990 and 28% in 1987, whereas 82% of patients had a serum albumin level > or 4.0 g/dL in 1993 compared with 58% in 1990 and 29% in 1987. Protein catabolic rate and hematocrit also increased from 1987 to 1993, but not serum cholesterol or triglyceride. The annual mortality rate declined from 16.1% in 1987 to 13.2% in 1990 and to 8.0% in 1993. The decrease in mortality appeared to be unrelated to differences in patient selection or comorbid conditions. Serum albumin levels, hematocrit, Kt/V, and protein catabolic rate were significantly related to patient survival after age, sex, and diabetic status had been adjusted. Furthermore, there was a positive correlation between Kt/Vs and serum albumin concentration (r = 0.216, P < 0.001). Thus it appears that increasing the dose of dialysis improves serum albumin levels and perhaps survival rate in hemodialysis patients as well.

Effect of the membrane biocompatibility on nutritional parameters in chronic hemodialysis patients

Malnutrition is highly prevalent in chronic hemodialysis patients and is an important determinant of their morbidity and mortality. Several recent studies have suggested that the inflammatory response associated with the biocompatibility of the dialysis membranes is a potential contributing factor. In a prospective study of 159 new hemodialysis patients from two centers randomized to either a low-flux biocompatible (BCM) membrane or a low-flux bioincompatible (BICM) membrane, we measured the long-term effects of biocompatibility on several nutritional parameters, including estimated dry weight, serum albumin, insulin-like growth factor-1 (IGF-1), and prealbumin over 18 months. Our results show that the BCM group had a mean (+/- SD) increase in their dry weight of 2.96 +/- 6.88 kg at month 12 and 4.36 +/- 8.57 kg at month 18 (P < 0.05 vs. baseline for both), whereas no change in mean weight was observed in BICM group. Following initiation of hemodialysis, a significant increase was observed in serum albumin levels in both groups of patients. However, the biocompatible group had an earlier and more marked increase in serum albumin levels compared to the BICM group. The average increase in serum albumin compared to baseline was consistently greater than 0.25 g/dl after seven months in the BCM group, but did not reach this level until 12 months after initiation of dialysis in the BICM group. The difference between the groups was statistically significant at months 7, 8, and 10 (P < 0.05, higher in the BCM group). Furthermore, the overall difference in serum albumin concentration between the two groups was larger in the center where the dose of dialysis was equivalent (P < 0.001). A consistently higher value was also observed in IGF-1 levels for BCM patients compared to BICM group (P = NS). In a further analysis, changes in IGF-1 levels, but not prealbumin, predicted the subsequent changes in serum albumin. We conclude that biocompatible hemodialysis membranes favorably impact on the nutritional status of chronic hemodialysis patients, independently of the flux characteristics of the membranes, and that IGF-1 may be an early marker of nutritional status.

A proposed glossary for dialysis kinetics

Quantification of the dialysis dose and assessment of nutritional status and response to nutritional therapy have become standard parts of the management of the chronic dialysis patient. Although advances in these areas have led to a more rational basis for therapy, certain misconceptions and points of confusion appear to have occurred. Recognizing the importance of a standard nomenclature to the development of concepts and the communication of research findings, we have attempted to compile a list of terms that are commonly used in the field of dialysis. New terms have been proposed for current ones that do not seem adequate. In addition, we have discussed potential methodologies for obtaining more accurate data for dialysis kinetics and for precise monitoring of nutritional intake and status. It is hoped that this glossary will stimulate discussion that will lead to refinements in terminology and concepts that will, in turn, improve research and practice in nephrology. It is anticipated that many of these definitions and recommendations will be modified or superseded as the management of patients with renal failure continues to advance.

The significance of protein intake and catabolism

Diet and nutrition are integral to the management of individuals with renal disease. Uremia engenders anorexia, nausea, meat aversion, and emesis, disturbances that ultimately reduce appetite and cause weight loss and malnutrition. Protein restriction can alleviate these uremic symptoms and improve patient health and vigor, but overly zealous protein restriction may, itself, produce malnutrition. This is particularly likely when energy intake is restricted by either design or anorexia. End-stage renal disease patients require renal replacement therapy for survival, and although dialysis is life sustaining, it neither replaces normal kidney function nor obviates the need for dietary management. In this setting of controlled, persistent uremia, undernutrition can develop surreptitiously. Dialysis physicians have long regarded malnutrition as a sign of uncontrolled uremia and failing health. This supposition has now been validated by epidemiologic studies demonstrating that serum albumin and protein catabolic rate (PCR) discriminate between dialysis patients at high and low risk of death or illness. This correlation of undernutrition with health and survival persists across wide ranges of age, medical diagnoses, and dialysis prescriptions. Because PCR is readily measured using urea kinetic analyses, it has been promoted as a patient monitoring tool and under steady-state conditions it is a reliable method of determining protein intake. Although a single PCR measurement does not integrate day-to-day dietary and metabolic fluctuations and contains an inherent uncertainty of +/- 20%, sequential measurements can be used to assess changes in an individual's dietary protein intake. PCR defines nitrogen losses and, when normalized to a realistic index of metabolic activity (metabolically active body size), it can disclose subtle individual variances in nitrogen utilization. These normalized protein catabolic rates (NPCR) do not, however, measure or describe overall nutrition. The normalization schemes employed are based on population averages and only approximate an individual's true metabolic activity. Thus, using NPCR to define nutritional needs can result in overfeeding obese and underfeeding wasted subjects. Instead, nutritional adequacy should be defined by clinical inspection and comparison with defined standards. Once that state is defined, and desirable protein and calorie intakes are determined, NPCR can be used to monitor the patient's ability to maintain homeostasis.

Current standards for dialysis adequacy

Multiple lines of evidence suggest that inadequately prescribed or delivered dosage of hemodialysis is associated with increased morbidity and mortality. Conversely, retrospective studies indicate that increased levels of hemodialysis reverse this trend of poor outcome. The results of the National Cooperative Dialysis Study (NCDS), a prospective and randomized trial, suggested that urea kinetic modeling was a valid method of quantifying the dose of hemodialysis delivered and also identified a level of treatment below which a number of adverse events occurred. In the ensuing years, urea kinetic modeling has been increasingly applied to quantitate dialysis. The application of the NCDS results as well as the limitations of the study are reviewed, and the modifications in applying urea kinetic modeling due to urea rebound are discussed. To assess the impact of newer membranes and higher levels of dialysis on an older hemodialysis population with more comorbid conditions than the subjects studied in the NCDS, a 5-year, multicenter, prospective and randomized trial, the HEMO Study, has recently been initiated.

Simplified equations for monitoring Kt/V, PCRn, eKt/V, and ePCRn

Although computer solution of the differential equations used in urea kinetic modeling has its advantages, simplified formulas that are actually approximate algebraic solutions to the same equations in the clinically useful range are also useful. The Kt/V can be resolved from the predialysis to postdialysis urea nitrogen ratio (R), the weight loss (UF), session length in hours (t), and anthropometric or modeled volume (V) using the equation: KtV = In (R - 0.008 x t) + (4 - 3.5 x R) x 0.55 UF/V. The equilibrated Kt/V (eKTV) can be estimated from the single-pool arterial Kt/V (spaKTV) or the single-pool venous Kt/V (spmvKTV) using a rate equation based on the regional blood flow model of urea kinetics: eKTV = spaKTV - (0.60)(spaKTV)/t + 0.03 = spmvKTV - (0.46) (spmvKTV)/t + 0.02. The normalized protein catabolic rate (PCRn) can be determined from either the single-pool or equilibrated Kt/V based on the predialysis urea nitrogen level (C0) and the Kt/V (KTV) using the generalized equation: PCRn = C0/(a + bKTV + c/ + KTV) + 0.168, where the constants a, b, and c vary depending on the dialysis schedule and the time of the week that the predialysis blood specimen has been drawn. Such equations can be used either for retrospective surveys, or for quality assurance purposes, as well as for bedside guidance in an individual patient. The actual modeled urea distribution volume can also be easily computed if some effort is made to estimate the dialyzer urea clearance.

Accuracy of urea removal estimated by kinetic models

The most accurate method for assessing the dialysis dose delivered during high efficiency/flux hemodialysis has not been established. Most current indices of dialysis dose are based on blood-side urea measurements, and thus estimate urea removal. Unfortunately, these methods may lead to inappropriately short dialysis during high flux or high efficiency dialysis, perhaps because of inaccuracies in estimating the amount of urea removal. It is unknown whether these clearance-based approaches can accurately predict either absolute or fractional net urea removal, the latter being equivalent to the solute removal index (SRI). Therefore, we compared the urea removal calculated by five blood-side kinetic methods: (1) urea reduction ration, (2) 1-pool, (3) 2-pool models, and the (4) Smye and (5) Daugirdas formulae. These were compared with the gold standard measurement by direct dialysate quantification. Eight stable patients receiving high-flux hemodialysis were studied over four sessions each. BUN was measured at 0, 45 minutes, 90 minutes, end dialysis, one hour after dialysis (equilibrium value), and 48 hours later. Total body water was determined from the dialysate urea removal; the urea generation rate was calculated using one hour post-dialysis and 48-hour BUN values. Both the total body water and urea generation rate were provided to the 1- and 2-pool models to optimize accuracy. The urea reduction ratio overestimated SRI. The 1-pool model overestimated both absolute urea removal and SRI in 28 of 32 sessions. The 2-pool model slightly underestimated both absolute urea removal and SRI. In contrast, the Smye and Daugirdas formulas accurately estimated SRI.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanisms of hypoalbuminemia in hemodialysis patients

Hypoalbuminemia is the most powerful predictor of mortality in end-stage renal disease. Since protein-calorie malnutrition can decrease albumin synthesis it is assumed that hypoalbuminemia results principally from malnutrition in these patients, but albumin synthesis may also be decreased as part of the acute-phase response, and hypoalbuminemia can also result from redistribution of albumin pools or from albumin losses. We measured albumin synthesis, fractional catabolic rate, and distribution from the turnover of [125I] human albumin in six hemodialysis patients with plasma albumin less than 35 mg/ml and in six patients with plasma albumin greater than 40 mg/ml. Patients with liver disease, HIV, or other infection were excluded. Both groups were maintained with high-flux polysulfone dialyzers for more than three months. Kt/Vurea and PCR were measured during each dialysis (N = 12 to 18/patient). A four-day calorie and protein intake was determined by dietary history and long-term nutritional status was determined anthropometrically. Measured variables included serum urea, creatinine, transferrin, and the positive acute-phase proteins alpha 2- macroglobulin, C-reactive protein, ferritin, and IGF-1. Albumin synthesis was significantly reduced in the low albumin group. There were no differences in dietary intake, body composition, PCR, BUN, creatinine, or Kt/Vurea. Plasma albumin concentration correlated negatively with ferritin, C-reactive protein and alpha 2-macroglobulin. Albumin synthesis rate correlated negatively with both alpha 2-macroglobulin and Kt/Vurea. Both plasma albumin concentration and synthesis rate correlated positively with IGF-1, and both were independent of PCR and all other nutrition-related variables.(ABSTRACT TRUNCATED AT 250 WORDS)

Morbidity and mortality in hemodialysis: the role of schedules

Hemodialysis is an efficient therapy for endstage renal failure. This treatment, however, must be used in an optimal fashion, i.e., with the best technology and the most adequate schedules. Unfortunately and especially for economic reasons, these basic therapeutic principles are often not respected. As a consequence, morbidity and mortality in maintenance hemodialysis patients have increased. This article underlines four points that could influence mortality in maintenance hemodialysis patients: nutrition, adequacy of hemodialysis, blood pressure control and treatment time.

Interventions to treat malnutrition in dialysis patients: the role of the dose of dialysis, intradialytic parenteral nutrition, and growth hormone

Protein and calorie malnutrition often starts before initiation of dialysis, and reflects the anorexia and the catabolic state of chronic renal failure. In the face of inadequate dialysis, which perpetuates the uremic state, malnutrition often worsens. Several studies, though not all, suggest that optimal dialysis improves nutritional status of dialysis patients. Such optimal dialysis now must include the use of biocompatible membranes to deliver Kt/V > 1.4 (urea reduction ratio > 65%). Additional interventions can include the use of enteral or intravenous hyperalimentation, and recombinant growth factors such as growth hormone or insulin-like growth factor-1. Importantly, studies to document the improvement in the morbidity and mortality of patients with these interventions are still needed and require large multicenter trials.

What dialysis dose should be provided in acute renal failure? A review

Increased dialysis dose has been shown to improve morbidity and survival in chronic hemodialysis patients. Despite improvement in care and technological aspects of renal replacement therapy, mortality rates of acute renal failure (ARF) have remained essentially unchanged for over two decades, exceeding 50% in most studies. The occurrence of ARF in older patients with more complicated medical and surgical conditions has contributed to this lack of outcome amelioration, and death of ARF patients is now more frequently caused by underlying disease than ARF itself. A recent prospective survey at this institution found a mortality rate of 79.1% among a total of 363 ARF medical and surgical intensive care unit patients, with a mean age near 60 years and a mean admission APACHE II score of over 20, who were treated by intermittent hemodialysis and continuous renal replacement therapy (CRRT). Nonsurvivors had a mean of over four failed systems, in addition to the renal failure, compared with survivors who had less than four. The standards for dialysis adequacy in ARF are not currently defined. Increased catabolism seen in ARF patients in the intensive care unit may justify large dialysis dose delivery. An apparent influence of delivered dialysis dose on the outcome of ARF intensive care unit patients has been recently observed at our institution. Compared with nonsurvivors, survivors had received significantly higher dialysis dose, as assessed by Kt/V and urea reduction ratio. In ARF patients, the discrepancy between delivered versus prescribed dialysis dose may be particularly important and contributed to by the following: reduced blood flow rate and dialysis time consequent to patient intolerance; lower dialyzer in vivo clearances, particularly in heparin-free dialysis; blood recirculation when using temporary vascular access; and postdialysis urea rebound. Prolonging the course of renal failure is one of the risks attributed to frequent dialysis; hypotension and ultrafiltration combined with a deficient renal autoregulation can result in further renal damage. The detrimental effects of bioincompatible membranes have been demonstrated with an induced-delay of renal function recovery. A recent study has reported benefits of biocompatible membranes in terms of potential for renal recovery and maintenance of urine output during dialytic support when compared with bioincompatible membranes. CRRT offers many advantages over intermittent hemodialysis for ARF intensive care unit patients: better hemodynamic tolerance, avoidance of solute rebound, and removal of serum sepsis mediators. However, CRRT have not yet been firmly shown to improve survival rates. Recently, urea kinetics have been used to estimate dialysis dose provided by CRRT.(ABSTRACT TRUNCATED AT 400 WORDS)

Death risk predictors among peritoneal dialysis and hemodialysis patients: a preliminary comparison

Variables associated with survival among 1,522 peritoneal dialysis patients and 16,404 hemodialysis patients who received treatment during 1992 were evaluated. Analysis was performed separately for the treatment types and for the combined patient group. In general, the associates of survival appear similar among patients receiving peritoneal or hemodialysis. Important variables appear related to nutrition, acid-base status (which is related to nutrition), and age.

Markers for survival in dialysis: a seven-year prospective study

Serum biochemical markers suggestive of undernutrition are directly correlated with mortality in hemodialysis and peritoneal dialysis patients. In particular, serum albumin is the most powerful predictor of survival. We have prospectively examined the relationship of single baseline measurements of serum albumin, cholesterol, creatinine, apoproteins, and prealbumin in 250 hemodialysis patients and 140 patients maintained on continuous ambulatory peritoneal dialysis (CAPD) monitored up to 7 years (1987 to 1994). Other variables studied included age, race, gender, diabetes, and number of months on dialysis. Observed survival was computed by the Kaplan-Meier method. Cox's proportional hazards model was used to determine independent predictors of mortality risk. Age, diabetes, prior months on dialysis, and low levels of serum albumin, creatinine, and cholesterol were important and independent predictors of mortality risk in hemodialysis patients. For peritoneal dialysis patients, the independent predictors of mortality risk were age, diabetes, and low serum albumin and serum creatinine. Prealbumin, a serum protein with rapid turnover and relatively small pool, was an important and independent risk predictor in both hemodialysis and CAPD patients. In addition, prealbumin was more highly correlated with other nutritional markers than was albumin. In summary, these findings suggest that biochemical measures associated with visceral and somatic protein depletion are predominant long-term mortality risk factors in patients maintained on hemodialysis and CAPD.

Why are dialysis patients malnourished?

There are multiple causes of protein-energy malnutrition in maintenance dialysis patients. The requirements of protein in dialysis patients are higher than in healthy individuals, and the intake of protein and energy in relation to the requirements is frequently low. Anorexia may be caused by uremia and underdialysis. There is experimental evidence that dialyzable uremic toxins accumulate in renal failure and suppress the appetite. In addition there are several psychosocial and comorbidity factors that may hamper adequate nutrition. There are also several factors in dialysis patients that may enhance protein catabolism and increase protein requirements, such as low energy intake, metabolic acidosis, dialytic loss of glucose, protein and amino acids and other catabolic effects of the dialytic procedures, as well as effects of infections and other comorbidity factors. The relative importance of the various factors that cause anorexia and stimulate protein catabolism is still not well understood.

Isolated rat hepatocyte metabolism is affected by chronic renal failure

Metabolic changes due to chronic renal failure (CRF) were studied in isolated liver cells. In 14 CRF and 14 sham-operated rats, liver cells were isolated by the Berry and Friend method and incubated with various substrates in order to study gluconeogenesis, ureagenesis, ketogenesis, oxygen consumption as well as cytosolic and mitochondrial adenine nucleotide content. CRF rat hepatocytes exhibited a 25% to 45% decrease in gluconeogenesis and ureagenesis (P < 0.05) from all the tested substrates (lactate plus pyruvate, fructose, glycerol, dihydroxyacetone, alanine and glutamine for gluconeogenesis and alanine, glutamine, ammonia and ammonia plus ornithine for ureagenesis), while endogenous rates were unaffected. CRF did not alter ketone body production (acetoacetate and beta-hydroxybutyrate) from oleate or octanoate. In the presence of either oleate, lactate plus pyruvate or ammonia, oxygen uptake as well as cytosolic and mitochondrial total adenine nucleotides were unaffected by CRF, while the mitochondrial ATP/ADP ratio decreased (P < 0.001). Thus, this study of hepatocyte intermediary metabolism during CRF showed an alteration of only gluconeogenesis and ureagenesis pathways. Moreover, the association of normal oxygen uptake together with decreased mitochondrial ATP/ADP ratio suggest a possible increase in hepatocyte ATP demand during uremia.

Hyperhomocysteinemia and traditional cardiovascular disease risk factors in end-stage renal disease patients on dialysis: a case-control study

Hyperhomocysteinemia occurs frequently in end-stage renal disease (ESRD), but its prevalence in comparison with traditional cardiovascular disease (CVD) risk factors is unknown. Fasting total plasma homocysteine, potential determinants of plasma homocysteine (i.e., plasma B-vitamins and serine), total and HDL cholesterol, glucose, and creatinine, were determined in 24 ESRD patients on dialysis, and 24 age, gender, and race matched Framingham Offspring Study controls with normal renal function. Presence of clinical CVD and CVD risk factors was established by standardized methods. Mean plasma homocysteine was markedly higher in the ESRD patients versus controls (22.7 vs. 9.5 mumol/l). ESRD patients were 33 times more likely than controls to have hyperhomocysteinemia (> 15.8 mumol/l) (95% confidence interval, 5.7-189.6). Hyperhomocysteinemia persisted in the ESRD patients despite normal to supernormal B-vitamin status. Plasma serine levels below the tenth percentile of the control distribution were found in 75% of the ESRD patients. Oral serine supplementation caused a 37% increase in mean plasma serine, but had no effect on plasma homocysteine in four ESRD patients with supernormal plasma folate, low plasma serine, and hyperhomocysteinemia. Given its unusually high prevalence, improved management of hyperhomocysteinemia might reduce CVD sequelae in ESRD.

Congestive heart failure in dialysis patients: prevalence, incidence, prognosis and risk factors

Cardiovascular disease is the most common cause of death in dialysis subjects. Congestive heart failure (CHF) is a common presenting symptom of cardiovascular disease in the dialysis population. Information regarding prevalence, incidence, risk factors and prognosis is crucial for planning rational interventional studies. A prospective multicenter cohort study of 432 dialysis patients followed for a mean of 41 months was carried out. Prospective information on a variety of risk factors was collected. Annual echocardiography and clinical assessment was performed. Major endpoints included death and the development of morbid cardiovascular events. One hundred and thirty-three (31%) subjects had CHF at the time of initiation of dialysis therapy. Multivariate analysis showed that the following risk factors were significantly and independently associated with CHF at baseline: systolic dysfunction, older age, diabetes mellitus and ischemic heart disease. Seventy-six of 299 subjects (25%) who did not have baseline CHF subsequently developed CHF during their course on dialysis. Compared to those subjects who never developed CHF (N = 218) multivariate analysis identified the following risk factors for the development of CHF: older age, anemia during dialysis therapy, hypoalbuminemia, hypertension during dialysis therapy, and systolic dysfunction. Seventy-five of the 133 (56%) subjects with CHF at baseline had recurrent CHF during follow-up. Independent and significant risk factors for CHF recurrence were ischemic heart disease and systolic dysfunction, anemia during dialysis therapy and hypoalbuminemia. The median survival of subjects with CHF at baseline was 36 months compared to 62 months in subjects without CHF. In this study the prevalence of CHF on starting ESRD therapy and the subsequent annual incidence was high.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of systolic blood pressure in determining prognosis of hemodialyzed patients

The role of blood pressure in determining the prognosis of hemodialyzed patients was examined in 195 patients who were introduced to hemodialysis. The relationship between blood pressure and survival or death was analyzed. In 46 patients who died within 3 years after the introduction of hemodialysis (nonsurvivors), the age was higher (61 +/- 2 years v 50 +/- 1 years), the occurrence of diabetic nephropathy was higher, and the systolic pressure was higher in both the introduction (178 +/- 4 mm Hg v 167 +/- 2 mm Hg) and maintenance (165 +/- 4 mm Hg v 147 +/- 2 mm Hg) phases than in 132 patients who survived more than 3 years (survivors). On the other hand, there were no significant differences in diastolic pressure during either phase between the two groups of patients. When diabetic nephropathy was excluded, only systolic pressure during the maintenance phase was higher in the nonsurvivors than in the survivors. Therefore, based on systolic pressure during the maintenance phase, patients were divided into two groups, the HT group (> or = 160 mm Hg) and the NT group (< 160 mm Hg), and cumulative survival rates were compared. Whether all patients, only those patients with diabetic nephropathy, or only those patients without diabetic nephropathy were examined, the survival rate was higher in the NT group than in the HT group.(ABSTRACT TRUNCATED AT 250 WORDS)

Dialysate protein losses with bleach processed polysulphone dialyzers

We measured dialysate protein losses from polysulphone dialyzers undergoing repetitive processing with bleach and formaldehyde. The entire dialysate was collected during the first, fifth and tenth use of F-80 dialyzers. Dialysate protein concentration was 1.5 +/- 0.4 mg/dl N = 11 +/- SEM) during the first use, 2.1 +/- 0.3 mg/dl during the fifth use and 3.6 +/- 0.5 mg/dl (N = 10) during the tenth use. In a follow-up study, dialyzers were evaluated for up to 25 uses. After 12 to 15 uses dialysate protein was 7.9 +/- 0.8 mg/dl (N = 13), after 16 to 20 uses; 12.0 +/- 1.2 mg/dl (N = 13) and after 23 to 25 uses; 19.9 +/- 2.1 mg/dl (N = 5). Mean dialysate volume was 83.9 +/- 1.1 liters (N = 63) yielding total protein losses of up to 20.7 grams per treatment. Dialysate albumin losses, which were unmeasurable during the first use of the dialyzers, revealed a similar increase with reuse resulting in a mean value of 14.4 +/- 3.2 mg/dl after 23 to 25 reuses (N = 5). Dialysate beta-2 microglobulin (beta 2m) levels were 1.05 +/- 0.13 mg/l for dialyzers bleached < 10 times (N = 32) versus 1.54 +/- 0.15 mg/liter for dialyzers bleached > 10 times (N = 31, P < 0.02 vs. < 10 reuses). A random sampling of dialyzers processed without bleach for 8, 14, 15, 24 and 25 reuses revealed minimal protein losses, ranging from 1.4 to 2.7 mg/dl with no relation to reuse number and no measureable albumin.(ABSTRACT TRUNCATED AT 250 WORDS)

[Role of hepatocellular insufficiency and kidney failure on nutritional management]

Chronic liver disease as well as chronic renal failure are responsible for abnormal nutrient metabolism and high rates of undernutrition. Although surgery is frequently required in such patients, the perioperative nutritional management has not yet been extensively studied in these conditions. During chronic liver disease, preoperative nutritional status and postoperative outcome are correlated. However, nutritional status can only be considered as one out of several factors of the prognosis, including the grade of liver insufficiency and the type of surgical procedure. Thus, it is difficult to evaluate the real influence of undernutrition on postoperative outcome. Similarly, the usefulness of preoperative nutrition is not definitely demonstrated in this condition. The nutritional requirements of patients with liver cirrhosis are estimated to be protein 1g and 30-35 kcal.kg-1.d-1. The duration of nutritional supplementation before surgery may not exceed 10 days. Postoperative parenteral nutrition seems to be well tolerated during chronic liver disease. Although some data in the literature suggest that it may be of interest after liver transplantation, the efficacy of postoperative parenteral nutrition needs to be proven in larger series. In chronically uraemic patients, the effects of undernutrition on postoperative morbidity and mortality have been poorly studied. Infectious complications after renal transplantation are favoured by several factors, including immunosuppressive therapy and malnutrition. The efficacy as well as the tolerance of perioperative nutritional support in patients with chronic renal failure are poorly known. In haemodialysis patients, candidates for renal graft, the nutritional status is usually well preserved when the recommended nutritional needs are provided: proteins 1.2-1.4 g and 35-40 kcal.kg-1.d-1.

Clinical and echocardiographic disease in patients starting end-stage renal disease therapy

End-stage renal disease (ESRD) patients have a high cardiovascular mortality rate. Precise estimates of the prevalence, risk factors and prognosis of different manifestations of cardiac disease are unavailable. In this study a prospective cohort of 433 ESRD patients was followed from the start of ESRD therapy for a mean of 41 months. Baseline clinical assessment and echocardiography were performed on all patients. The major outcome measure was death while on dialysis therapy. Clinical manifestations of cardiovascular disease were highly prevalent at the start of ESRD therapy: 14% had coronary artery disease, 19% angina pectoris, 31% cardiac failure, 7% dysrhythmia and 8% peripheral vascular disease. On echocardiography 15% had systolic dysfunction, 32% left ventricular dilatation and 74% left ventricular hypertrophy. The overall median survival time was 50 months. Age, diabetes mellitus, cardiac failure, peripheral vascular disease and systolic dysfunction independently predicted death in all time frames. Coronary artery disease was associated with a worse prognosis in patients with cardiac failure at baseline. High left ventricular cavity volume and mass index were independently associated with death after two years. The independent associations of the different echocardiographic abnormalities were: systolic dysfunction-older age and coronary artery disease; left ventricular dilatation-male gender, anemia, hypocalcemia and hyperphosphatemia; left ventricular hypertrophy-older age, female gender, wide arterial pulse pressure, low blood urea and hypoalbuminemia. We conclude that clinical and echocardiographic cardiovascular disease are already present in a very high proportion of patients starting ESRD therapy and are independent mortality factors.

Role of dialysis dose on morbidity and mortality in maintenance hemodialysis patients

The United States dialysis population has an excessive mortality rate that cannot be fully explained by comorbid conditions or demographic factors. The quantity of dialysis has been suggested to be insufficient. This report reviews the several dialysis-related factors that impact on mortality. Since the National Cooperative Dialysis Study in 1983, there have been no controlled trials. However, numerous retrospective and two recent larger prospective studies indicate that increasing the quantity of dialysis by 40% to 50% of that traditionally provided in the United States will significantly improve survival. This is equivalent to a Kt/V of less than 1.2 and possibly less than 1.4 using single pool urea kinetics. It is estimated that this would save an additional 8,000 to 16,000 lives per year.

The association of intradialytic parenteral nutrition administration with survival in hemodialysis patients

Hemodialysis patients who had received intradialytic parenteral nutrition (IDPN) during 1991 were identified. These patients were compared with unexposed controls after adjusting for demographic variables, baseline renal diagnosis, diabetic status, serum albumin (ALB), creatinine (CRE), and urea reduction ratio. At lower levels of ALB (< or = 3.4 g/dL), treatment with IDPN was associated with a reduction in the odds of death at 1 year, an effect that became stronger at lower levels of CRE (< or = 8.0 mg/dL). In contrast, treatment with IDPN in patients with normal ALB was associated with increased mortality. Time trend analyses of ALB and CRE demonstrated progressive increases toward pretreatment levels in IDPN recipients that were not evident in control subjects. These time trend data suggest that in undernourished hemodialysis patients, IDPN can effect the serum levels of valid biochemical surrogates of visceral and somatic protein nutrition. Albeit retrospective, the improvement in survival at year's end among patients with ALB < or = 3.4 g/dL suggests that malnutrition and its attendant ill effects in hemodialysis patients may respond to aggressive therapeutic intervention, such as IDPN. These important findings should be prospectively confirmed in a randomized clinical trial.

Hemodialysis therapy in the United States: what is the dose and does it matter?

There is an ongoing discussion in the renal community about how to monitor the treatment of hemodialysis patients in the United States. Comparison of the US patient experience to that of other countries with populations of similar health status is one way to assess treatment. Another technique involves examining the level of dialysis therapy US patients receive. This paper reviews recent studies which found that the United States has higher mortality than both Japan and Europe and provides additional information as to why those comparisons might be underestimating the mortality differences. We also examine the data on the level of dialysis US patients receive, both as a prescription and as delivered care. We conclude that US patients receive less hemodialysis therapy than their European and Japanese counterparts, and that in general US patients are not receiving the level of dialysis they were prescribed. These factors are correlated with an increased mortality among US hemodialysis patients.

Effect of nutrition on morbidity and mortality in maintenance dialysis patients

Protein-calorie malnutrition is common in maintenance dialysis patients. Malnutrition is mild to moderate in approximately 33% of maintenance dialysis patients and severe in approximately 6% to 8%. There are many causes of protein-calorie malnutrition in maintenance dialysis patients; the three major causes are probably low nutrient intakes, intercurrent or underlying illnesses, and the dialysis procedure itself. Malnutrition is a major risk factor for mortality in maintenance dialysis patients. This has been shown most clearly for serum albumin, which is the nutritional parameter that has been most heavily studied. Low dietary of protein or other nutrients and protein-calorie malnutrition revealed by the results of different chemistry analyses are also directly correlated with mortality rates. These data do not prove that poor nutritional intake or malnutrition is a cause of the high morbidity and mortality in maintenance dialysis patients, and randomized, prospective controlled clinical trials are necessary to answer this question. However, the data are consistent with the thesis that malnutrition or inadequate nutrient intake do contribute to high morbidity and mortality in these patients. Although it is possible that increasing the dose of dialysis (eg, Kt/V) will lead to increased appetite and nutrient intake, experience suggests that raising the dose of dialysis, by itself, will not optimize nutritional intake in these individuals. To achieve satisfactory nutritional intake and healthy nutritional status, other interventions will need to be developed.

Deficiencies in delivered hemodialysis therapy due to missed and shortened treatments

The frequency of missed and shortened hemodialysis treatments was assessed in a randomly selected sample of 860 ESRD patients from 54 dialysis units. Data were collected for three sequential 4-week periods covering 28,108 treatments. During each of these 4-week periods, 5.1% to 7.6% of patients missed at least one treatment, 26.8% to 32.3% of patients had at least one shortened treatment, and 6.6% to 7.9% of patients missed 10% or more of their prescribed therapy. Over the entire 12-week period, 50% of patients had either missed or shortened treatments (or both). Missed and shortened treatments are prevalent enough to account for clinically important deficiencies in delivered dialysis for a significant number of patients.

Kt/V, nutritional parameters, serum cortisol, and insulin growth factor-1 levels and patient outcome in hemodialysis

Despite many technical advances in dialysis care, morbidity and mortality in chronic hemodialysis patients in the United States remains high. In this study, we analyzed the effects of Kt/V, nutritional parameters (serum albumin level, triceps skin-fold thickness, mid-arm muscle circumference, and normalized protein catabolic rate), and predialysis serum cortisol and insulin growth factor-1 levels on predicting morbidity and mortality. The cohort studied consisted of 52 patients recruited from a single outpatient dialysis facility. Cox proportional hazards modeling indicated that only Kt/V predicted subsequent mortality (P = 0.02), while both predialysis cortisol levels (P = 0.03) and Kt/V (P = 0.03) predicted hospitalization. Kaplan-Meier analysis demonstrated that the ability of cortisol levels to predict hospitalization was largely confined to the group with values greater than 22 micrograms/dL predialysis. High serum cortisol levels were correlated with low serum albumin levels and a trend toward low triceps skin-fold thickness and higher normalized protein catabolic rate, suggesting a catabolic state. Both predialysis serum cortisol and insulin growth factor-1 levels were higher than those in age- and sex-matched normal human controls. These results demonstrate the importance role of Kt/V in predicting subsequent hospitalization rates and mortality, and that high predialysis serum cortisol levels correlate with a high hospitalization rate.

Amino acid and albumin losses during hemodialysis

Protein and calorie malnutrition are prevalent in chronic hemodialysis (HD) patients and has been linked to increased mortality and morbidity in this patient population. Concern has been raised that the open pore structure of high flux membranes may induce the loss of more amino acids (AA) compared to low flux membranes. To address this issue, we prospectively analyzed pre- and post-HD plasma AA profiles with three different membranes in nine patients. Simultaneously, we measured dialysate AA losses during HD. The membranes studied were: cellulosic (cuprophane-CU), low flux polymethylmethacrylate (LF-PMMA), and high flux polysulfone (HF-PS) during their first use. Our results show that pre-HD plasma AA profiles were abnormal compared to controls and decreased significantly during HD with all dialyzers. The use of HF-PS membranes resulted in significantly more AA losses into the dialysate when compared to LF-PMMA membranes (mean +/- SD; 8.0 +/- 2.8 g/dialysis for HF-PS, 6.1 +/- 1.5 g/dialysis for LF-PMMA, p < 0.05, and 7.2 +/- 2.6 g/dialysis for CU membranes, P = NS). When adjusted for surface area and blood flow, AA losses were not different between any of the dialyzers. We also measured dialysate AA losses during the sixth reuse of the HF-PS membrane. Losses of total AA increased by 50% during the sixth reuse of HF-PS membrane compared to its first use. In addition, albumin was detected in the dialysate during the sixth reuse of HF-PS membrane. We therefore measured albumin losses in all patients dialyzed with HF-PS membranes as a function of reuse.(ABSTRACT TRUNCATED AT 250 WORDS)

Adequacy of dialysis

Adequate dialysis is not easily defined. The concept that there is a relationship between dialysis dose and survival is gradually gaining acceptance. Nutritional status and possibly the type of dialyzer membrane used also influence survival in hemodialysis patients. The roles of physicians, patient care staff, technicians, nutritionists, and social workers in assuring adequacy can be clearly delineated in practice. Until recently, health status and quality of life evaluations have received less attention than clinical and laboratory parameters of adequacy. Instruments used to assess quality of life must be further developed and integrated with survival and morbidity data to improve the level of care provided for dialysis patients. The tools are available to enhance adequacy; they need to be utilized.

Chronic dialysis treatment: clinical outcome and related processes of care

The selection of primary clinical outcome by which to evaluate the success of a therapy is discussed. Outcome should be relevant to the treatment, important to the patient and to the public health, and easy to measure with little associated variance. The odds of death is chosen as the primary outcome by which to evaluate chronic dialysis treatment because the purpose of dialysis is to preserve life. The odds of death is then correlated with the processes of care, which themselves may be measurable and therefore viewed as outcome of other processes. A general model for outcome research using existing data and for evaluating the relationships among processes and outcome is discussed using a large patient cohort analysis as an example. The analysis suggests that two dimensions of the care process account for most of the explainable death odds difference among patients: a dialysis intensity-related dimension and a nutrition-related dimension. Experience has suggested that knowledge of these principles combined with simple measurements has, over time, led dialysis professionals to increase the intensity of the dialysis treatment they deliver. That was not the case for the nutrition-related dimension. We speculate that these professionals understand, from prior knowledge, how to control dialysis intensity but do not possess similar knowledge about nutritional therapeutics for dialysis patients. Therefore, a better understanding of nutritional therapeutics will be required to achieve maximum reduction of mortality rates.

Facility mortality rates for new end-stage renal disease patients: implications for quality improvement

End-stage renal disease networks can provide clinicians with valuable information about treatment outcome among their patients compared with those of other providers. These comparisons can help clinicians identify potential quality of care problems and efficiently allocate resources for quality improvement. We have illustrated this application of network information by examining the mortality rates for newly treated end-stage renal disease patients in 161 dialysis facilities in North Carolina, South Carolina, and Georgia. We found that mortality rates were high (an average of 19.2 deaths per 100 years of treatment) and variable (ranging from 0 to 43 deaths per 100 dialysis years). The risk of a patient dying in a facility at the 75th percentile of mortality was 50% higher than that of a patient in a facility at the 25th percentile. Adjusting for patient characteristics (case mix) left considerable variation in the risk of dying among individual dialysis facilities unexplained, suggesting that other treatment center-specific aspects of care contributed to the differences in mortality. After controlling for factors associated with increased mortality, the risk of a patient dying in a facility at the 75th percentile of mortality was 70% greater than that of a patient in a facility at the 25th percentile of mortality. Most facilities, but not all, with the highest unadjusted mortality rates also had the highest adjusted mortality. We conclude that treatment outcome comparisons that have been adjusted to account for case mix among facilities can be provided by network surveillance systems and, when properly understood by providers, might stimulate the search for facility-specific, nonpatient factors that contribute to these outcomes.

Continued survival of older hemodialysis patients: investigation of psychosocial predictors

This study investigated whether social and/or psychologic factors help to predict older dialysis patients' continued survival. A stratified (by race and sex) random sample of patients aged 60+ years was selected from the ESRD Network census of all patients in that age category residing in a single southeastern state (Georgia) and receiving chronic dialysis as of November 1987; personal interviews with patients were completed in 1988. This analysis includes 287 patients (mean age, 69 years) receiving outpatient hemodialysis for whom primary cause of renal failure and functional status data were complete. Patient tracking and vital statistics data determined that 49% of the sample survived as of October 31, 1990. Study variables included demographic, dialysis, health status, social situation, and psychologic outlook variables reported at the patients' 1988 interviews. Log rank tests showed univariate associations between patients' continued survival and race/gender, recovery time following dialysis treatments, cardiovascular co-morbidity, exercise activity score, freedom from health limitation of daily activity, functional status, leisure activity score, self-rated health status, overall life satisfaction, depression, and public religiosity. The Cox proportional hazards model was fit to the data, with continued survival from the time of the 1988 interview as the dependent variable. There was a significantly increased mortality risk for white men relative to the other race/gender groups and for patients reporting severely impaired functional status at the 1988 interview. With functional status in the model, no other social or psychologic variables were significant predictors of mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of intradialytic parenteral nutrition on mortality rates in end-stage renal disease care

Several studies have now demonstrated that low serum albumin and/or low protein catabolic rates correlate with increased risk of death in the chronic hemodialysis patient. A study involving 81 patients receiving thrice-weekly hemodialysis treatments and who had either a low serum albumin and/or protein catabolic rate was conducted to compare the effect of intradialytic parenteral nutrition (IDPN) on mortality rates. Fifty patients received IDPN and 31 patients did not. Thirty-eight of the patients were black (47%), 34 were white (42%), and 9 were Hispanic (11%). The study included 33 diabetic patients (41%), 20 of whom received IDPN. Nondiabetic patients received an average of 725 kcal/hemodialysis treatment and diabetic patients received an average of 670 kcal/hemodialysis treatment. The average length of treatment was 9 months. The results of the study revealed a better survival rate (64% v 52%) for patients treated with IDPN. Using Cox analysis, the IDPN-treated group had a significantly better survival rate (P < 0.01). Serum albumin increased by 12% in the survivors. There was no difference in survival when considered separately for diabetic and nondiabetic patients who received IDPN (mortality rate for diabetics: 50% for treated patients and 54% for untreated patients; mortality rate for nondiabetics: 26% for treated patients and 44% for untreated patients). However, the nondiabetic treated patients had the lowest mortality rates. In conclusion, correction of hypoalbuminemia by IDPN significantly reduced mortality rates overall.

Advance prediction of early death in patients starting maintenance dialysis

Accurate information on short-term prognosis is needed to help patients, their doctors, and society to make appropriate decisions concerning starting dialysis. We sought to develop a clinically applicable prognostic scoring system to aid in the prediction of death within 6 months of starting maintenance dialysis. Factors potentially predictive of early death were examined retrospectively in an inception cohort of all 325 patients starting dialysis for irreversible renal failure between 1980 and 1991 at a single tertiary care center. The overall mortality rate was 22% at 6 months. Age, cardiac failure, ischemic heart disease, dysrhythmia requiring therapy, severe peripheral vascular disease, advanced neoplasia, ventilator dependency, coma, systemic sepsis, and hepatic failure were independent, significant, prognostic indicators for early death. Multivariate models were used to suggest weights for these variables in a simplified scoring system. Patients with scores < or = 4 (N = 201) had a 6-month mortality rate of 4%, whereas those with a score higher than 9 (N = 21) had a 6-month mortality rate of 100%. Thus, when age and multiple comorbid illnesses were taken into account, it was possible to identify with 100% accuracy 29% of the patients who died within 6 months of starting maintenance dialysis therapy, accounting for 6.5% of the cohort studied. A larger prospective study is warranted to validate this scoring system.

Survival of hemodialysis patients in the United States is improved with a greater quantity of dialysis

The mortality rate for hemodialysis patients in the United States is higher than in other industrialized countries. Some attribute this to insufficient quantities of prescribed and delivered dialysis. A multicenter study in Dallas dialysis centers (Dallas Nephrology Associates) was begun in 1989 to assess the impact of increasing the delivered quantity of dialysis on mortality in subsequent years. Dialysis dose was measured by urea kinetic modeling. Kt/V, reflecting the fractional volume of body water clearance of urea during a dialysis treatment, was purposefully increased from 1.18 starting in 1989 to 1.46 in 1992. Additionally, the dialysis dose measured by the urea reduction ratio, the fractional reduction of blood urea nitrogen concentration caused by a dialysis treatment, increased from 63.0% to 69.6% between 1990 and 1992. Outcome analytical methods included both crude and standardized mortality rates and mortality ratios standardized to large end-stage renal disease databases at the United States Renal Data System and at National Medical Care, Inc. Crude mortality rates at Dallas Nephrology Associates decreased from 22.5% in 1989 to 18.1% in 1992. In comparison, between 1990 and 1992 the urea reduction ration in National Medical Care facilities increased from 57.1% to 62.5%. During that time crude mortality rates decreased from 21.8% to 19.5%. Crude mortality in the United States remained essentially unchanged in the same time period. By 1992, Dallas Nephrology Associates and National Medical Care had standardized mortality ratios of 0.77 and 0.74, respectively, compared with the US dialysis population, indicating almost 30% fewer observed deaths than expected. Monitoring dialysis dose by urea kinetic modeling or urea reduction ratio are equally effective in predicting improvement in patient survival. Improved survival is possible in the US end-stage renal disease program with greater amounts of dialysis. This strategy can save an estimated 8,000 to 16,000 lives per year.