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

Dialysis dose and frequency

BACKGROUND

From the beginning of the dialysis era, the issue of optimal dialysis dose and frequency has been a central topic in the delivery of dialysis treatment.

METHODS

We undertook a discussion to achieve a consensus on key points relating to dialysis dose and frequency, focusing on the relationships with clinical and patient outcomes.

RESULTS

Traditionally, dialysis adequacy has been quantified referring to the kinetics of urea, taken as a paradigm of all uraemic toxins, and applying the principles of pharmacokinetics using either single- or double-pool variable volume models. An index of dialysis dose is the fractional clearance of urea, which is commonly expressed as Kt/V. It can be calculated from blood urea concentration and haemodialysis (HD) parameters, according to the respective urea kinetic model or by means of simplified formulas. Similar principles are applicable to peritoneal dialysis (PD), where weekly Kt/V and creatinine clearance are used. Recommended minimal targets for dialysis adequacy have been defined by both American and European guidelines (DOQI and European Best Practice Guidelines, respectively). The question of how to improve the severe outcome of dialysis patients has recently come back to the fore, since the results of two recent randomized controlled trials led to the conclusion that, in thrice weekly HD and in PD, increasing the dialysis dose well above the minimum requirements of current American guidelines did not improve patient outcome. Daily HD (defined as a minimum of six HD sessions per week), in the form of either short daytime HD or long slow nocturnal HD, is regarded as a possibility to improve dialysis patient outcome. The results of the studies published so far indicate excellent results with respect to all outcomes analysed: optimal blood pressure control, regression of left ventricular hypertrophy and amelioration of left ventricular performance, improvement of renal anaemia, optimal hyperphosphataemia control, improvement of nutritional status, reduction in oxidative stress indices and improvement in quality of life. The basis for these beneficial effects is thought to be a more physiological clearance of solutes and water, with reduced pre- and post-HD solute concentrations and interdialytic oscillation, compared with traditional HD. Apart from concerns regarding reimbursement and organizational issues, no serious adverse effects have been described with daily HD. However, the evidence accumulated is limited mainly to retrospective cohorts, with small patient numbers and no adequate controls in most instances. Therefore, large prospective studies with adequate controls are required to make daily HD accepted by reimbursing authorities and patients.

CONCLUSIONS

Given the available observational and interventional body of evidence, there is no reason to reduce arbitrarily dialysis dose, particularly dialysis treatment time in HD patients treated three times weekly. Daily HD represents a very promising tool for improving dialysis outcomes and quality of life, although its impact on patient survival has not yet been proven definitively.

POOR NUTRITIONAL STATUS AND INFLAMMATION: Ultrapure Dialysate

To prevent pyrogenic reactions during hemodialysis, it is recommended that bacteria and endotoxin in dialysate not exceed 100-200 colony forming units (CFU)/ml and 0.25-2 endotoxin units (EU)/ml, respectively. While these limits are adequate to prevent acute pyrogenic reactions, data are accumulating to suggest they may not prevent stimulation of chronic inflammation in hemodialysis patients. Fragments of endotoxin and other bacterial products capable of stimulating immune cells cross low-flux and high-flux membranes in vitro. In clinical studies, use of ultrapure dialysate (bacteria < 0.1 CFU/ml and endotoxin < 0.03 EU/ml) is associated with lower concentrations of inflammatory markers and acute phase reactants than are observed with dialysate meeting current quality recommendations. Moreover, observational studies suggest a link between clinical outcomes and dialysate purity. Treatment of patients with ultrapure dialysate is reported to improve nutritional status, increase responsiveness to erythropoietin, slow the decline in residual renal function, lessen cardiovascular morbidity, and decrease the incidence of beta(2)-microglobulin amyloidosis. To date, however, none of these studies has shown a cause-and-effect relationship between dialysate purity and outcome. Further, there are no data defining the concentration dependence of outcomes on dialysate purity and the relative importance of dialysate purity as a trigger of inflammation remains unclear. While the technology exists to routinely provide ultrapure dialysate, controlled clinical trials are still needed to answer the question of whether or not introducing ultrapure dialysate into routine clinical practice represents an efficient use of limited resources in terms of decreasing inflammation and improving outcomes in hemodialysis patients.

POOR NUTRITIONAL STATUS AND INFLAMMATION: Anthropometric and Body Composition Assessment in Dialysis Patients

Anthropometric and body composition assessments provide important information about the nutritional status of dialysis patients. Anthropometric measurements describe body size, fatness, and leanness in dialysis patients and have been collected in the Modification of Diet in Renal Disease (MDRD) and HEMO studies. Dialysis patients present special problems for anthropometry, including decreased functional status and increased comorbidity, that challenge nutrition assessment methodology. Recumbent anthropometric techniques are recommended and stature is estimated from knee height. Measures of weight, stature, calf circumference, arm circumference, and triceps and subscapular skinfolds have recently been reported for dialysis patients, who tend to be shorter, lighter, and have less adipose tissue than healthy persons of the same age. The HEMO study anthropometric data provide a clinical reference for assessing the nutritional status of dialysis patients. The most common body composition methods used with dialysis patients are dual energy X-ray absorptiometry (DEXA), bioelectrical impedance, total body water (TBW), and prediction equations, but they are not recommended for assessment of predialysis patients, as estimates are best obtained postdialysis. The TBW volume used in calculating the dose of dialysis has commonly been predicted from the limited, out-of-date equations of Watson, based on nonrepresentative samples. New prediction equations are available for white, black, and Mexican American children and adults. Watson's data are not representative of the TBW of U.S. men and women. The greater TBW in non-Hispanic black men and women and Mexican American women reflects the greater levels of obesity in the U.S. population.

Dose of dialysis: key lessons from major observational studies and clinical trials

Analyses based on the National Cooperative Dialysis Study (NCDS) provided the impetus for routine quantification of delivered dialysis dose in hemodialysis practice throughout the world, by suggesting minimum targets for small solute (urea) clearance. Morbidity and mortality in dialysis populations remain high despite many technological advances in dialysis delivery. A number of observational studies reported association between higher dose of dialysis as measured by Kt/V urea or urea reduction ratio with lower mortality risk. During the 1990s, a steady increase in dialysis dose and a modest reduction in mortality on dialysis were observed. However, observational studies only reveal associations and are limited by selection bias and confounding. The Kidney Disease Outcomes Quality Initiative guidelines on dialysis adequacy are based on results of observational studies and expert opinion. Since the NCDS, the HEMO Study was the first major randomized clinical trial designed to study the effect of dose of dialysis and dialyzer flux on patient outcomes. Despite adequate separation of dose and flux, however, results of the trial did not prove a beneficial effect of higher dose. The Dialysis Outcomes and Practice Patterns Study (DOPPS), in a major international effort designed to examine the effect of practice patterns on outcomes, has made significant contributions to the topic of dialysis dose. The following review critically examines data from observational studies, including the DOPPS, and from the HEMO Study, emphasizing important lessons from both, and discusses future paradigms for achieving dialysis adequacy to improve patient outcomes.

Effects of Atorvastatin on Lipid Profile and Non-Traditional Cardiovascular Risk Factors in Diabetic Patients on Hemodialysis

BACKGROUND/AIMS

Dyslipidemia and non-traditional cardiovascular (CV) risk factors, such as lipoprotein(a) (Lp(a)), homocysteine, oxidative stress and inflammation, are important determinants in the increased CV risk of hemodialysis (HD) patients. The aim of our study was to evaluate the effects of atorvastatin on these parameters in one of the groups with the highest CV risk: diabetic patients with end-stage renal disease under HD therapy.

METHODS

Twenty maintenance HD diabetic patients (mean age 64 +/- 10 years, mean time on HD 25 +/- 11 months) with low-density lipoprotein cholesterol (LDL-C) >2.59 mmol/l received atorvastatin (10 mg/day) for 4 months. Lipid profile, including total cholesterol (TC), LDL-C, high-density lipoprotein cholesterol (HDL-C), triglycerides (TG), apolipoproteins A1 and B (Apo-A and Apo-B), and the non-traditional risk factors Lp(a), homocysteine, autoantibodies against oxidized LDL-C (anti-LDLox), total antioxidant status (TAS), and high sensitive C-reactive protein (hs-CRP), were measured at baseline and at the end of the study. Safety was assessed by clinical and laboratory (liver and muscle enzymes) monitoring once a month.

RESULTS

Mean percent reductions for TC, LDL-C and TG were 18.5% (p < 0.001), 22% (p < 0.001) and 19% (p < 0.01), respectively. The ratios of TC/HDL-C and LDL-C/HDL-C decreased after treatment (p < 0.05), whereas the ratios of LDL-C/Apo-B (p < 0.01) and Apo-A/Apo-B (p < 0.001) increased. No significant changes were observed in HDL-C. Concerning the non-traditional risk factors, levels of homocysteine, Lp(a), anti-LDLox and TAS did not change significantly. However, hs-CRP decreased from 5.4 (range 0.9-67.8) to 2.3 mg/l (range 0.4-21) (p < 0.01), whereas a concomitant increase in serum albumin was observed (from 38 +/- 2 to 40 +/- 1.7 g/l, p < 0.01). At baseline, hs-CRP was inversely associated with HDL-C and Apo-A, and directly related to Lp(a). The change in hs-CRP was inversely associated with the change of HDL-C, whereas a direct correlation was found with the change of TG.

CONCLUSIONS

Atorvastatin administration to diabetic patients on HD is associated with improvement of lipid profile and reduction of hs-CRP. These effects may be critical for the reduction of CV risk and mortality in HD population.

Outcome of patients with end-stage renal disease admitted to the intensive care unit

OBJECTIVES

To describe the clinical course of patients with end-stage renal disease (ESRD) admitted to the intensive care unit (ICU) and to compare the performance of Acute Physiology and Chronic Health Evaluation (APACHE) III and Sequential Organ Failure Assessment (SOFA) in predicting their outcome.

PATIENTS AND METHODS

This retrospective cohort study consisted of patients with ESRD admitted to 3 ICUs between January 1, 1997, and November 30, 2002. Data on demographics, APACHE III score, SOFA score, development of sepsis and organ failure, use of mechanical ventilation, and mortality were collected.

RESULTS

Of the 476 patients with ESRD who underwent dialysis during the study period, 93 (20%) required admission to the ICU. The most common ICU admission diagnosis was gastrointestinal bleeding. The first day median (Interquartile range) APACHE III score, SOFA score, and APACHE III predicted hospital mortality rate were 64 (47-79), 6 (5-8), and 12.9% (4.2%-30.8%), respectively. The observed ICU, hospital, and 30-day mortality rates were 9%, 16%, and 22%, respectively. Nonrenal organ failure developed in 48 patients (52%) and sepsis in 15 patients (16%). Mechanical ventilation was required In 26 patients (28%). The area under the receiver operating characteristic curve for the first-day APACHE III probability of hospital death in predicting 30-day mortality was 0.78 (95% confidence interval, 0.68-0.86) compared with 0.66 (95% confidence interval, 0.55-0.76) for the SOFA score (P = .16).

CONCLUSIONS

The observed hospital mortality of patients with ESRD admitted to the ICU is relatively low. There is no statistically significant difference in the performance of APACHE III and SOFA prognostic models in discriminating between 30-day survivors and nonsurvivors.

Measurement of dialyzer clearance, dialysis time, and body size: Death risk relationships among patients

BACKGROUND

Urea pharmacokinetic equation systems have contributed to better understanding of treatment dose among hemodialysis patients. The methods are indirect, however, and require the measurement of blood urea nitrogen (BUN) concentration before and after a dialysis session to estimate the total treatment dose that clinicians prescribe [urea clearance x dialysis time (Kt)] indexed to an estimate of body size [the volume of urea distribution in the body (V)] yielding the ratio, Kt/V. New technology permits direct on-line measurement of average small molecule clearance (Kecn) during each dialysis treatment that can be multiplied by time (t) to give a direct measurement of total treatment dose (Kt). This study evaluated the relationship of measured Kt with death risk. It also evaluated the relationship of simple body size measures to risk and also the combination of one such measure [body surface area (BSA)] with Kt to death risk.

METHODS

The data were taken from the Fresenius Medical Care (NA) (FMCNA) clinical database that included patients who had outcome data, height and weight measurements, and at least one average Kecn and t measurement during April 2002. Kecn, t, and the body size measures [body weight, body mass index (BMI), and BSA)] were averaged during the month. Those values were used as predictors of survival during the next 1 year in unadjusted and case mix adjusted proportional hazards (Cox) models.

RESULTS

Increasing values of Kecn, t, Kt and all of the body size measures were associated with lower death risk. The body size measure most closely associated with risk was the BSA that was used in subsequent models. Kt and BSA were independent risk predictors. There was a significant interaction between Kt and BSA in the case mix but not the unadjusted model indicating that the risk burden of lower total dialysis dose, Kt, may be greater among small than large patients.

CONCLUSION

The direct measurement of dialysis dose during each treatment is practical and the values reported by it are clinically relevant. Higher dose was associated with better survival in both small and large patients treated three times weekly. Furthermore, smaller patients may require proportionately greater total dose than larger patients to achieve comparable survival.

Uremic malnutrition is a predictor of death independent of inflammatory status

BACKGROUND

Several studies have pointed out the influence of nutritional parameters and/or indices of inflammation on morbidity and mortality. Often, these conditions coexist, and the relative importance of poor nutritional status and chronic inflammation in terms of predicting clinical outcomes in chronic hemodialysis (CHD) patients has not been clarified.

METHODS

We undertook a prospective cohort study analyzing time-dependent changes in several established nutritional and inflammatory markers, and their influence on mortality in 194 CHD patients (53% male, 36% white, 30% with diabetes mellitus, mean age 55.7 +/- 15.4 years) throughout a 57-month period. Serial measurements of serum concentrations of albumin, prealbumin, creatinine, transferrin, cholesterol, and C-reactive protein (CRP), as well as normalized protein catabolic rate, postdialysis weight, and phase angle and reactance by bioelectrical impedance analysis were performed every 3 months. Clinical outcomes were simultaneously assessed using indicators of mortality.

RESULTS

Serum albumin, serum prealbumin, serum creatinine, and phase angle were significant predictors of all-cause mortality, even after adjustment for serum CRP concentrations. Serum CRP concentrations were not significantly associated with mortality. Serum albumin concentrations and phase angle were also independent predictors of cardiovascular deaths in the multivariate model.

CONCLUSION

The nutritional status of CHD patients predicts mortality independent of concomitant presence or absence of inflammatory response. Prevention of, and timely intervention to treat uremic malnutrition by suitable means are necessary independent of the presence and/or therapy of inflammation in terms of improving clinical outcomes in CHD patients.

Serum parathyroid hormone is associated with increased mortality independent of 25-hydroxy vitamin d status, bone mass, and renal function in the frail and very old: a cohort study

Very frail older people constitute an increasing proportion of the aging population and often have vitamin D deficiency and impaired renal function. Primary hyperparathyroidism has been associated with increased mortality, but it is unclear whether secondary hyperparathyroidism is associated with increased mortality independent of renal function and vitamin D status. This study aimed to examine the effect of vitamin D deficiency and secondary hyperparathyroidism on mortality in frail older people after accounting for renal function and general measures of health. We evaluated 842 subjects (182 men with a mean age of 81.9 yr and 660 women with a mean age of 86.2 yr) living in residential aged care facilities in Sydney, Australia in a prospective, cohort study. Over a mean duration of follow-up of 31 months, 345 subjects died. Baseline serum 25-hydroxy vitamin D, serum PTH, and bone ultrasound attenuation were significantly associated with mortality in univariate and multivariate analyses (for PTH, a hazard ratio of 1.39 for time to death) after correcting for age and gender. In multivariate analyses that corrected for health status, nutritional status, and renal function, PTH remained a significant predictor of mortality but not 25-hydroxy vitamin D or bone ultrasound attenuation. Serum PTH appears to be associated with increased mortality in the frail elderly independent of vitamin D status, renal function, bone mass, and measures of general health. The mechanism of this effect requires further investigation.

Health-related quality of life of hemodialysis patients in Taiwan: a multicenter study

BACKGROUND/AIMS

Health-related quality of life (HRQOL) is an important determinant of treatment effectiveness in dialysis patients. To our knowledge, there are no reports evaluating HRQOL of hemodialysis (HD) in Chinese patients. The purpose of this study is to present our results about HRQOL using the 36-Item Short-Form (SF-36) questionnaire on Taiwanese hemodialysis patients.

METHODS

HRQOL was measured by using the SF-36 questionnaire in 497 HD patients in five hospitals.

RESULTS

The following attributes, male gender, age <50 years old, higher education level (HEL), marriage status, employment status (EPS), less comorbid medical condition (CMC), and non-diabetic patients (NDP) were all predicted on a better Physical Component Scale (PCS). Age <50 years old, body mass index >18.5, HEL, EPS and NDP were all predicted on a higher Mental Component Scale (MCS). Scales contributing to a summary measure of physical health, the PCS score was significantly lower in women (35.0 +/- 12.3) than in men (37.9 +/- 12.3). However, there was no difference in the MCS score between women and men. In multivariate analysis, age, CMC, diabetes, serum creatinine (SCr), and erythropoietin responsiveness were significant independent predictors of PCS. Diabetes, educational level, SCr, and erythropoietin responsiveness were significant independent predictors of MCS. All of the individual scales were lower in Taiwanese HD patients than in both the general Taiwanese and US population. Each of the individual scales and MCS scores were substantially lower in the Taiwan HD group than in the US HD cohort. However, the bodily pain of PCS was significantly higher in the Taiwan HD group, although the mean PCS scores for the Taiwan HD group and the US HD study participants were nearly equal at 36.3 and 36.1, respectively.

CONCLUSION

The physical and mental aspects of quality of life are substantially lower for Taiwanese HD patients, except for higher bodily pain tolerance. A number of demographic and clinical characteristics have a significant impact on HRQOL in Taiwanese HD patients.

Hematocrit was not validated as a surrogate end point for survival among epoetin-treated hemodialysis patients

OBJECTIVE

To evaluate the use of hematocrit as a surrogate end point for survival among end-stage renal disease (ESRD) patients treated with epoetin.

STUDY DESIGN AND SETTING

Using United States Renal Data System (USRDS) data, we conducted an observational prospective study to analyze the relationships among epoetin dose, hematocrit, and survival for 31,301 facility-based hemodialysis patients incident to ESRD therapy in 1998. To address our objective, we used criteria developed by Prentice based on results from a Cox regression model.

RESULTS

Results indicate that hematocrit is inversely associated with epoetin dose. For the same epoetin treatment-related achieved hematocrit levels, there were widely varying treatment-related survival outcomes, thereby challenging a central criterion required to empirically validate a surrogate end point.

CONCLUSION

Our results support earlier clinical trial and epidemiological data suggesting that hematocrit may not be a valid surrogate for survival among the epoetin-treated renal failure population. We hypothesize that hematocrit may not be in the causal pathway or that epoetin may have important mechanisms of action apart from increasing hematocrit. Effective treatment for anemia may therefore not be simply a matter of increasing hematocrit. This study has potential implications for revising the existing treatment guidelines for anemia management and selecting an appropriate treatment regimen.

Projecting the United States ESRD population: Issues regarding treatment of patients with ESRD

In 2001, there were 406,081 patients who received treatment for end-stage renal disease (ESRD), increasing by 4.2% since 2000. The number of patients with ESRD has grown consistently over the past decade, with the greatest rate of growth occurring among patients older than 75 years of age, and patients with comorbidities such as diabetes mellitus and hypertension. Current projections indicate that the population of patients with ESRD may reach more than 2 million by 2030. The overall mortality rate has fallen by 10% since 1988, with the greatest decline among patients incident to dialysis, and an increase among patients receiving dialysis for greater than five years. While the rate of hospitalization for ESRD patients has remained relatively constant, recent improvements in mortality are temporally associated with a greater proportion of patients achieving adequate benchmarks of care in dialytic processes, such as anemia correction and dose of dialysis. The ESRD program consumes 6.4% of the Medicare budget. On a per-patient per month basis, Medicare costs have risen between 1991 and 2001. While payments fell slightly during 1998 and 1999 because of changes in Medicare policies, more recent years have seen an upswing in total expenditures, presumably related to use of injectables not included in the composite rate. Continued growth in the number of new patients reaching ESRD, as well as improved mortality rates of ESRD patients, are both contributing to the current rise and projected epidemic of ESRD over the next 25 years. The current public health strategy of identification of patients with early kidney disease to slow their progression to ESRD, in addition to aggressive treatment strategies to minimize the morbidity and mortality of patients with ESRD, is essential toward affecting the growth and health of this population.

Low water-soluble uremic toxins

The uremic syndrome is the result of the retention of solutes, which under normal conditions are cleared by the healthy kidneys. Uremic retention products are arbitrarily subdivided according to their molecular weight. Low-molecular-weight molecules are characterized by a molecular weight below 500 D. The purpose of the present publication is to review the main water soluble, nonprotein bound uremic retention solutes, together with their main toxic effects. We will consecutively discuss creatinine, glomerulopressin, the guanidines, the methylamines, myo-inositol, oxalate, phenylacetyl-glutamine, phosphate, the polyamines, pseudouridine, the purines, the trihalomethanes, and urea per se.

Effects of high-flux hemodialysis on clinical outcomes: results of the HEMO study

Among the 1846 patients in the HEMO Study, chronic high-flux dialysis did not significantly affect the primary outcome of the all-cause mortality (ACM) rate or the main secondary composite outcomes, including the rates of first cardiac hospitalization or ACM, first infectious hospitalization or ACM, first 15% decrease in serum albumin levels or ACM, or all non-vascular access-related hospitalizations. The high-flux intervention, however, seemed to be associated with reduced risks of specific cardiac-related events. The relative risks (RR) for the high-flux arm, compared with the low-flux arm, were 0.80 [95% confidence interval (CI), 0.65 to 0.99] for cardiac death and 0.87 (95% CI, 0.76 to 1.00) for the composite of first cardiac hospitalization or cardiac death. Also, the effect of high-flux dialysis on ACM seemed to vary, depending on the duration of prior dialysis. This report presents secondary analyses to further explore the relationship between the flux intervention and the duration of dialysis with respect to various outcomes. The patients were stratified into a short-duration group and a long-duration group, on the basis of the mean duration of dialysis of 3.7 yr before randomization. In the subgroup that had been on dialysis for >3.7 yr, randomization to high-flux dialysis was associated with lower risks of ACM (RR, 0.68; 95% CI, 0.53 to 0.86; P = 0.001), the composite of first albumin level decrease or ACM (RR, 0.74; 95% CI, 0.60 to 0.91; P = 0.005), and cardiac deaths (RR, 0.63; 95% CI, 0.43 to 0.92; P = 0.016), compared with low-flux dialysis. No significant differences were observed in outcomes related to infection for either duration subgroup, however, and the trends for beneficial effects of high-flux dialysis on ACM rates were considerably weakened when the years of dialysis during the follow-up phase were combined with the prestudy years of dialysis in the analysis. For the subgroup of patients with <3.7 yr of dialysis before the study, assignment to high-flux dialysis had no significant effect on any of the examined clinical outcomes. These data suggest that high-flux dialysis might have a beneficial effect on cardiac outcomes. Because these results are derived from multiple statistical comparisons, however, they must be interpreted with caution. The subgroup results that demonstrate that patients with different durations of dialysis are affected differently by high-flux dialysis are interesting and require further study for confirmation.

Body size and outcomes on peritoneal dialysis in the United States

BACKGROUND

Being overweight is often cited as a relative contraindication to peritoneal dialysis. Our primary objective was to determine whether actual mortality rates support this opinion.

METHODS

Retrospective cohort study of United States Medicare patients initiating dialysis between 1995 and 2000 (N = 418,021; 11% peritoneal dialysis).

RESULTS

Seven percent were underweight [body mass index (BMI) < 18.5 kg/m2], 27% were overweight (BMI 25.0 to 29.9 kg/m2), and 23% were obese (BMI> 29.9 kg/m2) at dialysis initiation. Compared to those with normal BMI, the adjusted odds of initiating peritoneal dialysis were 0.70 (P < 0.05) in underweight, 1.12 (P < 0.05) in overweight, and 0.87 (P < 0.05) in obese subjects. Among peritoneal dialysis patients, adjusted mortality hazard ratios in the first, second, and third year were 1.45 (P < 0.05), 1.28 (P < 0.05), and 1.17 for the underweight, respectively; 0.84 (P < 0.05), 0.89 (P < 0.05), and 0.98 for the overweight, respectively; and 0.89 (P < 0.05), 0.99, and 1.00 for the obese, respectively. Apart from higher third-year mortality in the obese, associations were similar after censoring at a switch to hemodialysis. For transplantation, the corresponding results were 0.76 (P < 0.05), 0.90 (P < 0.05), and 0.88 for the underweight, respectively; 0.95, 1.06, and 0.93 for the overweight, respectively; and 0.62 (P < 0.05), 0.68, and 0.71 for the obese, respectively. For switching to hemodialysis, hazards ratios were 0.92, 0.97, and 0.80 for the underweight, respectively; 1.07, 1.11 (P < 0.05), and 1.03 for the overweight, respectively; and 1.28 (P < 0.05), 1.29 (P < 0.05), and 1.36 (P < 0.05) for the obese, respectively.

CONCLUSION

Although less likely to initiate peritoneal dialysis, overweight and obese peritoneal dialysis patients have longer survival than those with lower BMI, not adequately explained by lower transplantation and technique survival rates.

Predialysis nephrologic care and a functioning arteriovenous fistula at entry are associated with better survival in incident hemodialysis patients: an observational cohort study

BACKGROUND

Late nephrologist referral may adversely affect outcome in patients initiating maintenance hemodialysis therapy, mostly with temporary catheters that may further increase morbidity and mortality. Our aim was to evaluate the influence of 2 variables on mortality: presentation mode (planned versus unplanned) and type of access (arteriovenous fistula [AVF] versus temporary catheter) at entry.

METHODS

This was a 3-center, 5-year, prospective, observational, cohort study of 538 incident patients. Measurements included presentation mode, type of access, renal function and biochemical test results at entry, and stratification of risk groups. Main outcome measures were mortality and hospitalization.

RESULTS

Of 281 planned patients (52%), 73% initiated therapy with an AVF. Of 257 unplanned patients (48%), 70% initiated therapy with a catheter (P < 0.001). Multivariate Cox analysis showed that unplanned presentation (hazard ratio [HR], 1.73; 95% confidence interval [CI], 1.23 to 2.44) and initiation of therapy with catheter (HR, 1.75; 95% CI, 1.25 to 2.46) were independently associated with greater mortality and similar HRs after adjusting for confounders. At 12 months, the number of deaths was 3 times higher in both the unplanned versus planned groups and catheter versus AVF groups. The joint effect of unplanned dialysis initiation and catheter use had an additive impact on mortality (HR, 2.89; 95% CI, 1.97 to 4.22). Greater hematocrit (HR, 1.04; 95% CI, 1.01 to 1.09) and albumin level (HR, 1.79; 95% CI, 1.37 to 2.33) showed an independent association with survival, underscoring the benefits of predialysis care. Using Poisson regression, all-cause hospitalization (incidence rate ratio, 1.56; 95% CI, 1.36 to 1.79; P < 0.001) and infection-related (incidence rate ratio, 2.62; 95% CI, 1.91 to 3.59; P < 0.001) and vascular access-related (incidence rate ratio, 1.49; 95% CI, 1.15 to 1.94; P < 0.003) admissions were higher in unplanned patients initiating therapy with a catheter than in planned patients initiating therapy with an AVF, after adjusting for confounders.

CONCLUSION

Unplanned dialysis initiation and temporary catheter were independently associated with greater mortality rates in incident patients. The combined influence of both variables was associated with greater morbidity and mortality than either variable alone.

Inflammation, endothelial dysfunction, and platelet activation in patients with chronic kidney disease: the chronic renal impairment in Birmingham (CRIB) study

BACKGROUND

Studies in the general population suggest that low-grade inflammation, endothelial dysfunction, and platelet activation are associated with an increased risk of cardiovascular events.

METHODS

Markers of inflammation, endothelial dysfunction, and platelet activation were measured in 334 patients with chronic kidney disease (serum creatinine >1.47 mg/dL [>130 micromol/L] at screening) and compared with 2 age- and sex-matched control groups, 1 comprising 92 patients with coronary artery disease and the other comprising 96 apparently healthy individuals with no history of cardiovascular or kidney disease.

RESULTS

There was evidence of low-grade inflammation in the chronic renal impairment group compared with healthy controls, with higher concentrations of C-reactive protein (3.70 versus 2.18 mg/L, P < 0.01) and fibrinogen (3.48 versus 2.67 g/L, P < 0.001) and lower serum albumin concentration (41.8 versus 44.0 g/dL [418 versus 440 g/L], P < 0.001). More severe renal impairment was associated with a trend towards higher fibrinogen and lower albumin concentrations (both P < 0.001), although there was no association with higher C-reactive protein level. As compared to healthy controls, plasma von Willebrand factor (142 versus 108 IU/dL, P < 0.001) and soluble P-selectin concentrations (57.0 versus 43.3 ng/mL, P < 0.001) were also higher in the chronic renal impairment group. More severe renal impairment was associated with a trend towards higher levels of von Willebrand factor (P < 0.001) and of soluble P selectin (P < 0.05).

CONCLUSION

This cross-sectional analysis demonstrates that chronic kidney disease is associated with low-grade inflammation, endothelial dysfunction, and platelet activation, even among patients with moderate renal impairment.

Early clinical, quality-of-life, and biochemical changes of "daily hemodialysis" (6 dialyses per week)

BACKGROUND

Advantages associated with an increased frequency of hemodialysis have been reported previously. However, previous studies were either small or not controlled and did not detail early clinical, biochemical, quality-of-life, urea kinetic, and dynamic changes when patients switched from a conventional (3 times/wk) dialysis regimen to "daily" (6 times/wk) dialysis therapy when total weekly dialysis time was unchanged.

METHODS

A prospective sequential study with 21 patients as their own controls was performed. A 4-week period of conventional thrice-weekly dialysis (N = 240 treatments) was followed immediately by a 4-week period of daily (ie, 6 times/wk) dialysis (N = 480 treatments), in which each treatment was half the length of a conventional dialysis treatment session. Clinical parameters and symptoms during and between dialysis treatments were graded, and urea-related parameters, blood chemistry results, and nutritional data were determined.

RESULTS

Within 4 weeks of switching to this daily dialysis regimen, there were improvements in blood pressure, dialysis "unphysiology," intradialytic and interdialytic symptoms, and urea kinetics and dynamics. There were fewer machine alarms and less need for nursing interventions during dialysis. Nutrition and quality of life began to improve. There was no increase in blood access complications and no significant changes in blood chemistry results, hematologic parameters, or use of medications.

CONCLUSION

In this short-term study, daily dialysis appears to be a safe, better, and more physiological method to deliver dialysis care to patients with end-stage renal disease.

Dialysis dose and the effect of gender and body size on outcome in the HEMO Study

BACKGROUND

Gender and body size have been associated with survival in hemodialysis populations. In recent observational studies, overall mortality was similar in men and women and higher in small patients. The effect of dialysis dose in each of these subgroups has not been tested in a clinical trial.

METHODS

The HEMO Study was a controlled trial of dialysis dose and membrane flux in 1846 hemodialysis patients followed up for 6.6 years in 15 centers throughout the United States. We examined the effect of dialysis dose on mortality and on selected secondary outcomes in subgroups of patients.

RESULTS

Adjusting for age only, overall mortality was lower in patients with higher body weight (P < 0.001), higher body mass index (P < 0.001), and higher body water content determined by the Watson formula (Vw) (P < 0.001), but was not associated with gender (P= 0.27). The RR of mortality comparing the high dose with the standard dose group was related to gender (P= 0.014). Women randomized to the high dose had a lower mortality rate than women randomized to the standard dose (RR = 0.81, P= 0.02), while men randomized to the high dose had a nonsignificant trend for a higher mortality rate than men randomized to the standard dose (RR = 1.16, P= 0.16). Analysis of both genders combined showed no overall dose effect (R = 0.96, P= 0.52), as reported previously. Vw was greater than 35 L in 84% of men compared with 17% of women. However, the RR of mortality for the high versus standard dose remained lower in women than in men after adjustment for the interaction of dose with Vw or with other size parameters, including weight and body mass index. Conversely, the dose effect was not significantly related to size parameters after controlling for the relationship of the dose comparison with gender.

CONCLUSION

The data suggest that mortality and morbidity might be reduced by increasing the dialysis dose above the current standard in women but not in men. This effect was not explained by differences between men and women in age, race, or in several indices of body size. Because multiple comparisons were considered in this analysis, the role of gender on the effect of dialysis dose is suggestive and invites further study.

ACE gene polymorphism, left ventricular geometry, and mortality in diabetic patients with end-stage renal disease

The objectives of this study were to determine the association between angiotensin converting enzyme (ACE) gene polymorphism and left ventricular (LV) geometry, and to clarify independent effects of ACE genotype on mortality after commencing dialysis in diabetic patients with end-stage renal disease (ESRD). A total of 106 diabetic patients, 71 men and 35 women, 11 type 1 and 95 type 2 diabetic, 57 +/- 12 (mean +/- standard deviation (S.D.)) years of age, who started dialysis were studied. Patients with cardiac diseases and those treated with ACE inhibitors were excluded because of potential effects on LV performance. Echocardiographic examination was performed within +/-2 months of the start of dialysis. Relation between ACE genotype and LV mass index (LVMI) or relative wall thickness (RWT) at onset of dialysis, and impact of ACE genotype on survival after commencing dialysis were evaluated. There were no significant differences in LVMI or RWT in the three ACE genotype groups at onset of dialysis. However, mortality of patients with the ACE-DD genotype was significantly higher than patients with the DI and II genotypes (hazard ratio, 2.318; P=0.043), based on a survival analysis with a mean follow-up duration of 60 months. The higher mortality in patients with the DD genotype was confirmed to be independent of LV hypertrophy and increases in RWT. In diabetic patients with ESRD, ACE genotype has no association with LV mass or RWT at the start of dialysis, but does have an independent impact on patient survival thereafter.

Overcoming early learning barriers in hemodialysis patients: the use of screening and educational reinforcement to improve treatment outcomes

A dialysis team project to improve patient knowledge resulted in a significant improvement in patient understanding of health-risk behavior related to blood pressure and albumin management in a large hemodialysis clinic. This project demonstrates that brief intervention combined with a well-coordinated renal team can successfully steer the team's time and resources toward improving treatment outcomes, despite the busy feel of the day-to-day dialysis clinic. Analysis of the barriers to successfully educating the ESRD patient is performed and the full intervention is described. The nephrology social worker, the RN and an area manager of 5 outpatient dialysis clinics speak of their experience with the project. A participant (ESRD patient) describes his sense of satisfaction with care.

Supplementation with Alfacalcidol Increases Protein Intake and Serum Albumin Concentration in Patients Undergoing Hemodialysis with Hypoalbuminemia: Possible Role of Tumor Necrosis Factor-α

BACKGROUND

We have reported that vitamin D deficiency may be implicated in the pathogenesis of hypoalbuminemia observed in patients with end-stage renal disease, but the mechanism remains to be clarified. The aim of the present study was to determine whether supplementation with alfacalcidol might increase protein intake in hemodialyzed patients with hypoalbuminemia.

METHODS

Twelve patients with hypoalbuminemia under 3.5 g/dl undergoing maintenance hemodialysis and not taking active forms of vitamin D were orally supplemented with 0.5 microg of alfacalcidol daily for 8 weeks. Normalized protein catabolic rate (nPCR), an index of protein intake, and serum concentrations of albumin, interleukin-6 (IL-6), IL-1beta, and soluble tumor necrosis factor-alpha receptor-II (sTNFR-II), an index of tumor necrosis factor-alpha activity, were determined before and after supplementation with alfacalcidol.

RESULTS

Supplementation with alfacalcidol increased nPCR from 0.96 +/- 0.20 to 1.16 +/- 0.15 g/kg/day (p < 0.005), thereby increasing serum albumin concentration from a baseline of 3.13 +/- 0.35 to 3.32 +/- 0.29 g/dl (p < 0.05). The baseline serum concentrations of sTNFR-II and IL-6 were markedly elevated, whereas those of IL-1beta were under the detection limit. Supplementation with alfacalcidol significantly decreased serum concentration of sTNFR-II from 23.8 +/- 4.38 to 19.7 +/- 3.93 ng/ml (p < 0.001) but did not alter serum IL-6 concentration.

CONCLUSION

Supplementation with alfacalcidol can increase protein intake and serum albumin concentration in hemodialyzed patients with hypoalbuminemia, probably through the suppressed tumor necrosis factor activity.

Good measurement for good improvement work

PURPOSE

To provide guidance on using measurement to support the conduct of local quality improvement projects that will strengthen the evaluation of results and increase their potential for publication.

TARGET GROUP

Individuals leading quality improvement efforts who wish to enhance their use of measurement.

PROCEDURES TO PROMOTE GOOD MEASUREMENT

Eleven procedures are offered to promote intelligent measurement in quality improvement research that may become publishable: 1. Start with an important topic 2. Develop a clear aim statement 3. Turn the aim statement into key questions 4. Develop a theory about causes and effects, process changes and predictable sources of variation 5. Construct a research design and accompanying dummy data displays to answer your primary research questions 6. Develop and use operational definitions for each variable needed to make your dummy data displays 7. Design a data collection plan to gather information on each variable that will enable you to generate reliable, valid, and sensitive measures related to each research question 8. Pilot test the data collection plan, construct preliminary data displays, and revise your methods based on what you learn 9. Stay close to the data collection process as the data plan goes from idea to execution 10. Perform data analysis and display results in a way that answers your key questions. 11. Review and document the strengths and limitations of your measurement work and use this knowledge to guide intelligent interpretation of the observed results.

Optimum dietary protein requirement in nondiabetic maintenance hemodialysis patients

BACKGROUND

There is controversy about whether the dietary protein requirement of 1.2 g/kg/d for hemodialysis (HD) patients, in the nutritional guidelines recommended by the National Kidney Foundation-Kidney Disease Outcomes Quality Initiative (NKF-KDOQI), is reasonable.

METHODS

A cross-sectional study was conducted in 129 stable HD patients without diabetes (84 men, 45 women) to investigate the association between the protein equivalent of nitrogen appearance normalized by ideal body weight (nPNAibw), an index of protein intake, and skeletal muscle mass or other metabolic consequences. Patients were divided into 5 groups according to nPNAibw index. Midthigh muscle area (TMA), midthigh subcutaneous fat area (TSFA), abdominal muscle area (AMA), abdominal subcutaneous fat area (ASFA), and visceral fat area (AVFA) were measured using computed tomography, and various nutritional parameters were compared among these groups.

RESULTS

TMA and AMA values increased with increasing dietary protein intake from less than 0.7 g/kg/d to 0.9-1.1 g/kg/d and showed a plateau at greater than 0.9 to 1.1 g/kg/d of dietary protein intake. Conversely, fat mass, including TSFA, ASFA, and AVFA, and serum potassium concentration increased with graded protein intake, and no plateau was formed. Patients with nPNAibw greater than 1.3 g/kg/d satisfied the criterion of visceral obesity. Although serum prealbumin levels showed a trend similar to that of muscle mass, there was no significant difference in serum albumin levels among the study groups.

CONCLUSION

Optimal dietary protein requirement for patients undergoing maintenance HD in a stable condition appears to be less than the level recommended by the NKF-KDOQI nutritional guidelines.

Prevalence of acidosis and inflammation and their association with low serum albumin in chronic kidney disease

BACKGROUND

Low serum albumin is a strong risk factor for mortality, but its association with low serum bicarbonate and inflammation in the setting of mild to moderately decreased kidney function is uncertain.

METHODS

We analyzed data from 15594 subjects over the age of 20 who participated in the Third National Health and Nutrition Examination Survey (NHANES III). Glomerular filtration rate (GFR) in mL/min/1.73 m2 was estimated by the abbreviated Modification of Diet in Renal Disease (MDRD) equation using appropriately calibrated serum creatinine.

RESULTS

The age-adjusted prevalence of hypoalbuminemia (serum albumin <3.8 g/dL) at a GFR of 90, 60, 30, and 15 mL/min/1.73 m2 was 19%, 21%, 38%, and 59%, respectively, while the age-adjusted prevalence of C-reactive protein (CRP) >or= 0.22 mg/dL was 36%, 44%, 69%, and 81%, respectively, both P trend <0.001. Age, female gender, non-Hispanic black compared with non-Hispanic white race, diabetes, hypertension, hepatitis C, urine albumin: creatinine ratio >1 g/g, dietary protein intake, dietary caloric intake, serum bicarbonate, CRP, and GFR category were all significant predictors of hypoalbuminemia on univariate analysis. On simultaneously adjusting for the above variables, hypertension, diabetes, GFR, and dietary protein and caloric intake were no longer significant independent predictors of hypoalbuminemia. The adjusted odds ratio (OR) of serum bicarbonate (by quartile) for hypoalbuminemia was 1.0 for serum bicarbonate >28 mEq/L (reference), 1.25 for 26-28 mEq/L, 1.51 for 23-25 mEq/L, and 1.54 for <or=22 meq/L. The adjusted OR of CRP for hypoalbuminemia was 1.0 for CRP < 0.22 mg/dL (reference), 2.60 for 0.22-1.0 mg/dL, and 5.56 for >1.0 mg/dL.

CONCLUSION

Elevated CRP and low serum bicarbonate are independently associated with hypoalbuminemia, explaining much of the high prevalence of hypoalbuminemia in chronic kidney disease.

Correction of metabolic acidosis improves thyroid and growth hormone axes in haemodialysis patients

BACKGROUND

Chronic metabolic acidosis (CMA) in normal adults results in complex endocrine and metabolic alterations including growth hormone (GH) insensitivity, hypothyroidism, hyperglucocorticoidism, hypoalbuminaemia and loss of protein stores. Similar alterations occur in chronic renal failure, a prototypical state of CMA. We evaluated whether metabolic acidosis contributes to the endocrine and metabolic alterations characteristic of end-stage renal disease.

METHODS

We treated 14 chronic haemodialysis patients with daily oral Na-citrate for 4 weeks, yielding a steady-state pre-dialytic plasma bicarbonate concentration of 26.7 mmol/l, followed by 4 weeks of equimolar Na-chloride, yielding a steady-state pre-dialytic plasma bicarbonate of 20.2 mmol/l.

RESULTS

Blood pressure, body weight and dialysis adequacy were equivalent in the two protocols. Na-citrate treatment corrected CMA, improved GH insensitivity, increased and normalized plasma free T(3) concentration, and improved plasma albumin. Correction of CMA had no significant effect on measured cytokines (interleukin-1 beta and -6, tumour necrosis factor-alpha) or acute phase reactants (C-reactive protein, serum amyloid A, alpha(2)-macroglobulin).

CONCLUSION

CMA contributes to the derangements of the growth and thyroid hormone axes and to hypoalbuminaemia, but is not a modulator of systemic inflammation in dialysis patients. Correcting CMA may improve nutritional and metabolic parameters and thus lower morbidity and mortality.

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

BACKGROUND

Protein requirements in stable, adequately dialysed haemodialysis patients are not known and recommendations vary. It is not known whether increasing the dialysis dose above the accepted adequate level has a favourable effect on nutrition. The aim of this study was to determine whether prescribing a high protein diet and increasing the dose of dialysis would have a favourable effect on dietary protein intake and nutritional status in stable, adequately dialysed haemodialysis patients. Effects on hyperphosphataemia and acidosis were also studied.

METHODS

Patients were randomized to a high dialysis dose (HDD) group (target Kt/V(eq) of 1.4) or a regular dialysis dose (RDD) group (target Kt/V(eq) of 1.0). All patients were prescribed a high protein (HP) diet [1.3 g/kg of ideal body weight (IBW)/day] and a regular protein (RP) diet (0.9 g/kg/day), each during 40 weeks in a crossover design. In 50 patients, 23 in the HDD and 27 in the RDD group follow-up was > or =10 weeks. These patients, aged 56+/-15 years, were included in the analysis. Nutritional status was assessed by anthropometry, plasma albumin and a nutritional index.

RESULTS

Delivered Kt/V(eq) in the HDD group (1.26+/-0.14) was significantly higher than in the RDD group (1.02+/-0.08). Protein intake estimated from total nitrogen appearance (PNA) measurements and food records (DPI) was significantly higher during the HP diet (PNA(IBW), 1.01+/-0.18 g/kg/day; DPI(IBW), 1.15+/-0.18 g/kg/day) than during the RP diet (PNA(IBW), 0.90+/-0.14 g/kg/day; DPI(IBW), 0.94+/-0.11 g/kg/day). Increasing the dialysis dose did not increase protein intake either during the HP or RP diet. Plasma albumin (41.9+/-3.0 g/l) lean body mass (107+/-15% of normal values) and the nutritional index did not differ between the dialysis dose groups or protein diets and remained stable overtime. Dry body weight (97+/-14%) and total fat mass increased over time in the HDD group, but remained stable in the RDD group suggesting an effect of dialysis dose on energy balance. There was no effect of the protein diets on dry body weight or total fat mass. Plasma phosphate levels and oral bicarbonate supplements were lower in the HDD group, but were comparable between the protein diets.

CONCLUSIONS

Prescribing a HP diet resulted in a modest increase in actual protein intake, but increasing dialysis dose did not have a contributing effect. A HP diet or increasing the dialysis dose did not have a favourable effect on the nutritional status. A dietary protein intake of at least 0.9 g/kg IBW/day appears to be sufficient for adequately dialysed haemodialysis patients without overt malnutrition.

Eating Behavior Disorders in Uremia: A Question of Balance in Appetite Regulation

Eating and appetite disorders are frequent complications of the uremic syndrome which contribute to malnutrition in dialysis patients. The data suggest that uremic anorexia may occur with or without abdominal and visceral fat accumulation despite a lower food intake. This form of obesity (i.e., with low food intake and malnutrition) is more common in dialysis patients than obesity with high food intake. This article reviews the current knowledge regarding mechanisms responsible for appetite regulation in normal conditions and in uremic patients. Anorexia in dialysis patients has been historically considered as a sign of uremic toxicity due to "inadequate" dialysis as judged by uncertain means ("middle molecule" accumulation, Kt/V, "peak-concentration hypothesis," and others). We propose the tryptophan-serotonin hypothesis, based on a uremia-induced disorder in patients' amino acid profile--low concentrations of large neutral and branched-chain amino acids with high tryptophan levels. A high rate of tryptophan transport across the blood-brain barrier increases the synthesis of serotonin, a major appetite inhibitor. Inflammation may also play a role in the genesis of anorexia and malnutrition. For example, silent infection with Helicobacter pylori may be a source of cytokines with cachectic action; its eradication improves appetite and nutrition. The evaluation of appetite should take into account cultural and social aspects. Uremic patients showed a universal trend to carbohydrate preference and red meat refusal compared to healthy people. In contrast, white meat was less problematic. Uremic patients also have a remarkable attraction for citrics and strong flavors in general. Eating preferences or refusals have been related to the predominance of some appetite peptide modulators. High levels of cholecystokinin (CCK) (a powerful anorexigen) are associated with early satiety for carbohydrates and neuropeptide Y (NPY) (an orexigen) with repeated food intake. Obesity and elevated body mass index often falsely suggest a good nutritional status. In uremic patients (a hyperinsulinemia state), disorders in the regulation of fat distribution (insulin, leptin, insulin-like growth factor [IGF]-1, fatty acids, and disorders in receptors for insulin, lipoprotein lipase, mitochondrial uncoupling protein-2, and beta 3 adrenoreceptors) may cause abdominal fat accumulation without an increase in appetite. Finally, appetite regulation in uremia is highly complex. Disorders in adipose tissue, gastrointestinal and neuropeptides, retained or hyperproduced inflammatory end products, and central nervous system changes may all play a role. Uremic anorexia may be explained by a hypothalamic hyperserotoninergic state derived from a high concentration of tryptophan and low branched-chain amino acids.

Effects of dialyzer membrane on serum albumin levels in patients receiving hemodialysis

Biocompatibility of the dialyzer membrane has been thought to affect the nutritional status in patients receiving chronic hemodialysis. In a series of patients treated in an outpatient dialysis unit, serum albumin was measured before and after changing the dialyzer membrane from one of cellulose to one of polysulfone. There were 48 patients (25 men and 23 women) who had been on dialysis for a mean duration of 78.6 months. The follow-up period was at least 6 months for each type of membrane. Delivered dose of dialysis was higher using the polysulfone membrane but serum albumin was not affected by a change to the more biocompatible membrane. Nutritional considerations are not important in choosing a membrane for dialysis.

Protein homeostasis in chronic hemodialysis patients

PURPOSE OF REVIEW

Nutritional status is an important predictor of clinical outcome in chronic hemodialysis patients, as uremic malnutrition is strongly associated with an increased risk of death and hospitalization events. Decreased muscle mass is the most significant predictor of morbidity and mortality in these patients. Several factors that influence protein metabolism predispose chronic hemodialysis patients to increased catabolism and the loss of lean body mass. The purpose of this review is to discuss recent advances in the understanding of abnormalities in protein homeostasis in chronic hemodialysis patients.

RECENT FINDINGS

It has long been suspected that the hemodialysis procedure is a net catabolic event. Recent studies have indeed shown that the hemodialysis procedure induces a net protein catabolic state at the whole-body level as well as in skeletal muscle. There is evidence to suggest that these undesirable effects are caused by decreased protein synthesis and increased proteolysis. The provision of nutrients, either in the form of intradialytic parenteral nutrition or oral feeding during hemodialysis, can adequately compensate the catabolic effects of the hemodialysis procedure. Whereas the mechanisms of these effects have not been studied in detail, changes in extracellular amino acid concentrations and certain anabolic hormones such as insulin are important mediators of these actions.

SUMMARY

There is now indisputable evidence to suggest that the hemodialysis procedure leads to a highly catabolic state. Despite this, chronic hemodialysis patients can still achieve anabolism when given adequate protein supplementation to meet the metabolic requirements of hemodialysis, and when adequate insulin is present.

Prescribing an equilibrated intermittent hemodialysis dose in intensive care unit acute renal failure

BACKGROUND

Prospective, formal, blood-side, urea kinetic modeling (UKM) has yet to be applied in intermittent hemodialysis for acute renal failure (ARF). Methods for prescribing a target, equilibrated Kt/V (eKt/V) are described for this setting.

METHODS

Serial sessions (N= 108) were studied in 28 intensive care unit ARF patients. eKt/V was derived using delayed posthemodialyis urea samples and formal, double-pool UKM (eKt/Vref), and by applying the Daugirdas-Schneditz venous rate equation to pre- and posthemodialysis samples (eKt/Vrate). Individual components of prescribed and delivered dose were compared. Prescribed eKt/V values were determined using in vivo dialyzer clearance estimates and anthropometric (Watson and adjusted Chertow) and modeled urea volumes.

RESULTS

eKt/Vref (mean +/- SD = 0.91 +/- 0.26) was well-approximated by eKt/Vrate (0.92 +/- 0.25), R= 0.92. Modeled V exceeded Watson V by 25%+/- 29% (P < 0.001) and Adjusted Chertow V by 18%+/- 28% (P < 0.001), although the degree of overestimation diminished over time. This difference was influenced by access recirculation (AR) and use of saline flushes. The median % difference between Vdprate and Watson V was reduced to 1% after adjusting for AR for the 22 sessions with < or =1 saline flush. The median coefficients of variation for serial determinations of Adjusted Chertow V, modeled V, urea generation rate, and eKt/Vref were 2.7%, 12.2%, 30.1%, and 16.4%, respectively. Because of comparatively higher modeled urea Vs, delivered eKt/Vref was lower than prescribed eKt/V, based on Watson V or Adjusted Chertow V, by 0.13 and 0.08 Kt/V units. The median absolute errors of prescribed eKt/V vs. delivered therapy (eKt/Vref) were not large and were similar in prescriptions based on the Adjusted Chertow V (0.127) vs. those based on various double-pool modeled urea volumes (approximately 0.127).

CONCLUSION

Equilibrated Kt/V can be derived using formal, double-pool UKM in intensive care unit ARF patients, with the venous rate equation providing a practical alternative. A target eKt/V can be prescribed to within a median absolute error of less than 0.14 Kt/V units using practical prescription algorithms. The causes of the increased apparent volume of urea distribution appear to be multifactorial and deserve further investigation.

Hospitalization in the first year of renal replacement therapy for end-stage renal disease

BACKGROUND

The requirement for hospitalization of patients on dialysis is likely to be a surrogate marker of age and comorbid diseases. It may also reflect the level of care delivered, and substantially increases the cost of this expensive therapy.

AIM

To identify the factors most strongly associated with hospitalization.

DESIGN

Prospective population study.

METHODS

Data were recorded for all patients starting RRT in Scotland over one year, including the reasons for and duration of, each hospital admission during the first year of RRT. Factors most strongly associated with hospitalization were determined by Poisson regression analysis.

RESULTS

Overall, 526 patients were admitted to hospital on 1668 occasions (median 3, IQR 1-4) for 13384 days (median 13, IQR 4-35). Formation of vascular access for haemodialysis (HD) was the most frequent reason for admission, followed by infections. Age, comorbidity, mode of presentation for RRT and primary renal diagnosis were all significantly associated with prolonged hospitalization. Attainment of UK Renal Association standards for urea reduction ratio and serum albumin concentration, and vascular access in the form of arterio-venous fistulae were associated with less hospitalization in patients treated with HD by 90 days.

DISCUSSION

Patients in their first year of RRT have a high requirement for in-patient care, 8.6% of patient treatment days being spent in hospital. Vascular access formation, failure and complications account for a large proportion of this. Age and comorbidity prolong the time spent in hospital. As the RRT population continues to increase, with older patients and those with greater comorbidity, in-patient facilities must also expand.

RENAL RESEARCH INSTITUTE SYMPOSIUM: Efforts to Determine the Role of Oxidant Stress in Dialysis Outcomes

The role of elevated markers of oxidant stress needs to be established in longitudinal studies. Oxidant stress markers such as malonaldehyde (MDA), isoprostanes, and breath hydrocarbons warrant rigorous application to outcomes, if they are to be used as clinical parameters. For example, investigations of C-reactive protein (CRP), parathyroid hormone (PTH), and several other clinical indicators have shown that these markers can be used to predict outcomes such as morbidity and mortality. Long-term followup is needed for intervention studies with antioxidants, since effects with short-term studies may be focused on critically-ill individuals where intervention would not be expected to be effective. Oxidant stress studies in this population especially need a long-term approach to test the hypothesis that antioxidant intervention is beneficial.

ADEMEX and HEMO trials: where are we going?

Doubt has remained as to whether or not the K/DOQI recommended targets for adequacy of dialysis for peritoneal dialysis patients is appropriate (weekly Kt/V 2 + creatinine clearance 50-60 l/1.73 m(2)). The ADEMEX trial can be interpreted as indicating that lower targets might be acceptable. The HEMO trial, not yet published but presented in April 2002, casts doubts on the advantages of achieving higher than recommended small solute clearance targets. Taken together, these trials require that we broaden our concept of adequacy. There is also a risk of complacency with respect to dialysis adequacy because of these trials and this would be unwise.

Long-term study of high-comorbidity ESRD patients converted from conventional to short daily hemodialysis

BACKGROUND

Conventional hemodialysis (CHD) is associated with suboptimal clinical outcomes and high mortality rates. Daily hemodialysis (DHD) has been reported to improve outcomes and quality of life (QOL), predominantly in self-care or home dialysis populations. The effect of short DHD (sDHD) on patients with end-stage renal disease (ESRD) with high comorbidities has not been established.

METHODS

This prospective study compared clinical outcomes and QOL in high-comorbidity patients with ESRD converted from CHD to sDHD while maintaining the same total weekly dialysis time. Study patients had 4.0 +/- 1.7 major comorbid conditions in addition to ESRD. Standard dialysis parameters, antihypertensive and erythropoietin (EPO) requirements, Kidney Disease Quality of Life (KDQOL) measurements, vascular access problems, and hospitalization rates were compared while on sDHD therapy versus the previous 12 months on CHD therapy.

RESULTS

Forty-two patients were studied on sDHD therapy for 793 patient-months during a 72-month period. During sDHD, standard Kt/V increased 31%, hospitalization days decreased significantly by 34%, and vascular access problems did not increase. Cumulative survival was 33% at 6 years. In the 20 patients who remained on sDHD therapy for 12 months, after 1 year, we found significant improvements in KDQOL scores, a 69% reduction in antihypertensive medications with stable blood pressure, and a 45% reduction in EPO requirements with stable hematocrits. We hypothesize that these improvements are the result of the less extreme solute and fluid fluctuations and greater dialysis dose provided by sDHD, even when weekly dialysis time is unchanged.

CONCLUSION

High-comorbidity patients with ESRD converted to sDHD therapy had significantly improved clinical outcomes and QOL and decreased hospitalizations, with no increase in vascular access problems.

End-stage renal disease in Scotland: Outcomes and standards of care

BACKGROUND

The number of patients starting renal replacement therapy (RRT) for end-stage renal disease (ESRD) in the United Kingdom rises annually. Patients are increasingly elderly with a greater prevalence of comorbid illness. Unadjusted survival, from the time of starting RRT, is not improving. The United Kingdom Renal Association has published recommended standards of treatment, which all United Kingdom nephrologists strive to attain. This study was devised to define the impact of attaining recommended treatment standards, adjusting for patient age and comorbid illnesses, upon survival on RRT in the United Kingdom population.

METHODS

A prospective, registry based, observational study of all patients starting RRT in Scotland over a 1-year period, followed for the first 2 years of RRT.

RESULTS

Of the 523 patients who were studied, 217 (41.5%) had died by 2 years of follow-up, 32% excluding deaths within the first 90 days. Age, comorbidity, weight when starting RRT, and attaining the recommended standards for albumin and hemoglobin had a significant impact upon survival.

CONCLUSION

This study has emphasized the very high mortality of patients starting RRT in Scotland. By paying close attention to the attainment of recommended standards of care for patients with ESRD, it may be possible to improve upon current mortality figures. The monitoring of such success is only possible if correction is made for age and comorbidity.

Near-infrared spectroscopic measurement of urea in dialysate samples collected during hemodialysis treatments

Single-beam spectra were collected over the combination region of the near-infrared spectrum for 80 samples collected from 15 people over a two-week period. Partial least-squares (PLS) regression was used to generate an optimized calibration model for urea. PLS calibration models accurately measure urea in the spent dialysate matrix. Prediction errors are on the order of 0.15 mM, which is sufficient for the clinical assessment of the dialysis process. In addition, the feasibility of a global calibration model is demonstrated by generating a calibration model from samples and spectra obtained from 12 people to predict the level of urea in samples collected from 3 different people. In this case, the standard error of prediction is 0.09 mM. Spectra were modified in order to systematically examine the impact of resolution and noise. Little impact is observed by altering the spectral resolution from 4 to 32 cm-1. Spectral noise, however, plays an important role in the accuracy of these calibration models. Increasing the magnitude of the spectral noise increases the prediction errors and increases the width of the spectral range necessary for extracting the analytical information. The utility of the method is demonstrated by analyzing dialysate samples collected during actual dialysis treatments. In addition, the necessary resolution and spectral quality necessary for reliable on-line urea monitoring is identified. These findings indicate that a dedicated, on-line urea spectrometer must posses a resolution of 16 cm-1 coupled with a sample thickness of 1.5 mm and spectral noise levels on the order of 25 micro-absorbance units when measured as the root-mean-square (RMS) noise of 100% lines.

A randomized, controlled study of the consequences of hemodialysis membrane composition on erythropoietic response

BACKGROUND

Membrane biocompatibility has long been thought to be relevant to hemodialysis outcomes and, possibly, renal anemia.

METHODS

We performed a randomized, controlled, single-center study comparing the consequences on renal anemia of 2 dialyzers of equivalent performance, but different composition, during 7 months. Two hundred eleven patients of an unselected dialysis population of 235 patients gave informed consent to undergo random assignment to either group A (SF170E; modified cellulose triacetate/midflux membrane; Nipro, Osaka, Japan) or group B (HF80LS; polysulfone/high-flux membrane; Fresenius, Bad Homburg, Germany). Anemia management was identical in both treatment groups and followed strict clinical protocols managed by computer algorithms. Dialysis adequacy, hemoglobin (Hb) level, ferritin level, percentage of red blood cell hypochromicity, C-reactive protein (CRP) level, and intravenous iron and epoetin doses were monitored monthly.

RESULTS

One hundred seventy-seven patients completed the 7-month study. Equilibrated Kt/V increased in both groups. Hb outcome improved overall, but did not differ between the 2 study groups. Epoetin dose was not significantly different after 7 months compared with baseline in either group. Hb level, epoetin dose, iron status, CRP level, dialysis Kt/V, and residual renal function did not differ between the 2 groups. A slight but significant negative correlation was identified between dialysis Kt/V and Hb level in the population as a whole (Spearman's correlation, -0.16; P = 0.04).

CONCLUSION

No significant epoetin-sparing effect was identified through the use of the high-flux polysulfone HF80LS membrane over the modified cellulose triacetate SF170E membrane. Although not a primary outcome for this study, there was a suggestion of benefit of improved Hb level, without increased need for epoetin, through increasing delivered dialysis dose.

Linkage of hypoalbuminemia, inflammation, and oxidative stress in patients receiving maintenance hemodialysis therapy

BACKGROUND

Hypoalbuminemia is a powerful predictor of cardiovascular mortality in maintenance hemodialysis patients. Increased biomarkers of acute-phase inflammation and oxidative stress are highly prevalent and also correlate with cardiovascular morbidity and mortality. The extent to which hypoalbuminemia, biomarkers of inflammation, and biomarkers of oxidative stress are linked in this patient population is unknown. We hypothesized that a high proportion of hypoalbuminemic hemodialysis patients also would manifest increased levels of biomarkers of inflammation and oxidative stress.

METHODS

We surveyed 600 maintenance hemodialysis patients and identified 18 severely hypoalbuminemic patients (serum albumin level < 3.2 g/dL [32 g/L]) without recent infection or hospitalization. We then identified 18 age-, race-, sex-, and diabetes-matched normoalbuminemic hemodialysis patients, as well as 18 age-, race-, sex-, and diabetes-matched healthy subjects, for cohort comparison. Measurements of plasma interleukin-6 (IL-6) levels, plasma protein reduced thiol content, plasma protein carbonyl content, and plasma free F2-isoprostane levels, as well as serum concentrations of C-reactive protein (CRP) and prealbumin, were performed for study purposes.

RESULTS

Levels of serum CRP, IL-6, plasma protein thiol oxidation, and protein carbonyl formation were significantly elevated in both hypoalbuminemic and normoalbuminemic hemodialysis patients compared with healthy subjects and also were significantly different in hypoalbuminemic maintenance dialysis patients compared with normoalbuminemic hemodialysis patients. Prealbumin levels were significantly lower in hypoalbuminemic hemodialysis patients than in other groups.

CONCLUSION

There is a high prevalence of inflammation and oxidative stress in the maintenance hemodialysis population. Levels of inflammatory and oxidative stress biomarkers are increased further in hypoalbuminemic compared with normoalbuminemic dialysis patients. Hypoalbuminemia, acute-phase inflammation, and oxidative stress may act synergistically to increase cardiovascular morbidity and mortality risk in maintenance hemodialysis patients.

Association between inflammatory mediators and muscle mass in long-term hemodialysis patients

BACKGROUND

Muscle wasting is highly prevalent in long-term hemodialysis (HD) patients. Although inflammatory indices have been associated with malnutrition in these patients, the role of inflammation in muscle wasting has not yet been determined.

METHODS

The relationship between the inflammatory mediators C-reactive protein (CRP) and interleukin-6 (IL-6) and the muscle mass indices thigh muscle area (TMA), measured by computed tomography, and creatinine (Cr) production, estimated by the Cr kinetic model (Cr-CKM), were investigated in 188 HD patients.

RESULTS

Serum IL-6 level (7.3 +/- 7.8 pg/mL) was significantly elevated in HD patients, whereas mean serum CRP level (4.8 +/- 7.5 mg/L) remained within the normal range. Similar to serum albumin, muscle mass indices had significantly negative correlations with both serum IL-6 and CRP levels (TMA/dry weight [DW] versus log IL-6, r = -0.28; P < 0.01; TMA/DW versus log CRP, r = -0.38; P < 0.001; Cr-CKM versus log IL-6, r = -0.31; P < 0.01; Cr-CKM versus log CRP, r = -0.24; P < 0.01). Although muscle mass indices also were associated with both age and sex, a multiple regression analysis confirmed that these inflammatory indices were significantly associated with muscle mass in HD patients.

CONCLUSION

Data indicate that muscle wasting is associated closely with inflammatory indices in long-term HD patients. It may be important to clarify the mechanism for the increasing inflammatory status and suppress the inflammatory response in these patients to improve their malnutrition and recover muscle mass.

Influence of left ventricular mass, uremia and hypertension on vagal tachycardic reserve

BACKGROUND

Left ventricular (LV) hypertrophy, arterial hypertension and end-stage renal disease (ESRD) are associated with deranged cardiac parasympathetic regulation and increased cardiovascular risk. These conditions often co-exist but little is known about the relative contribution of LV mass, arterial blood pressure and ESRD to impaired cardiac vagal tone. We evaluated the vagal tachycardic reserve (VTR) in subjects with normal renal function (age 58.4 +/- 6.6 years, n = 19) and in patients under chronic hemodialysis (HD) (age 62.6 +/- 13.2 years, n = 30) having wide ranges of LV mass and blood pressure.

METHODS

VTR was estimated from the tachycardic response to atropine (15 microg/kg intravenously) administered during a dipyridamole-atropine stress-echo test performed as part of the diagnostic work-up for identification of inducible myocardial ischemia. LV hypertrophy (defined as LV mass index > 125 g/m2 in both genders) was present in 20 HD patients and in nine control patients. Only patients free of inducible myocardial ischemia were included in the study.

RESULTS

The atropine-mediated tachycardia was: (i) significantly smaller in HD patients than in control patients (34.7 +/- 7.6 versus 60.8 +/- 10.5 beats/min, P < 0.01); (ii) independently and inversely related to LV mass (multiple regression; partial coefficients, -0.139 in HD patients and -0.382 in controls, both P < 0.01) and to mean blood pressure (-0.171 in HD patients and -0.268 in controls, both P < 0.01).

CONCLUSIONS

LV mass is the strongest (inverse) determinant of VTR. Blood pressure as well as the patient's renal status are also independent correlates of VTR, and the concomitance of LV hypertrophy and ESRD exacerbates the impairment of VTR.

End-stage renal disease: endocrine aspects of treatment

End-stage renal disease (ESRD) is a deadly disease unless supportive treatment is administered in the form of haemodialysis, peritoneal dialysis or kidney transplantation. Although marked improvements have occurred in the efficiency of dialysis and in overall care, patients with ESRD still have poor long-term survival. The outcome is largely dependent on age, nutritional status, efficiency of dialysis and underlying reason for renal failure. As a consequence of renal failure, these patients experience a number of endocrine and metabolic disorders that may affect their well being and overall outcome. Disturbances in the somatotropic axis have been documented at several different levels, including an end-organ resistance to both growth hormone (GH) and insulin-like growth factor-I (IGF-I). A consequence seen in childhood is reduced growth velocity and short final height that may be overcome by long-term GH treatment, and it is possible that metabolism and nutritional status in adults with ESRD may be influenced by these abnormalities. Although a few small trials of GH treatment in adults with ESRD suggest that nutritional status may improve, long-term trials are needed to demonstrate other benefit of such treatment. This review will give a brief description of endocrine problems in adult patients with ESRD with a focus on the somatotropic axis, and it will review the experience reported in published trials of GH treatment in this patient group.

C-reactive protein, lipoprotein(a), homocysteine, and male sex contribute to carotid atherosclerosis in peritoneal dialysis patients

BACKGROUND

In patients with end-stage renal disease, the morbidity and mortality of cardiovascular disease are substantially greater than in the general population. Advancement in understanding the pathogenesis of atherosclerotic vascular disease suggests a central role of inflammation in atherogenesis. However, clinical data evaluating the role of inflammation in atherogenesis are sparse in peritoneal dialysis (PD) patients.

METHODS

We measured serum C-reactive protein (CRP), intact parathyroid hormone, lipoprotein(a) [Lp(a)], interleukin-1 receptor antagonist (IL-1Ra), tumor necrosis factor soluble receptor (TNF-sR), fibrinogen, and plasma homocysteine (Hcy), as well as intima-media thickness (IMT) and number of atherosclerotic plaques (plaque score [PS]) in the carotid arteries by means of carotid B-mode ultrasonography in 59 PD patients (35 men, 24 women; mean age, 52.4 years; average dialysis period, 36 months). All patients had chronic glomerulonephritis.

RESULTS

Sixty-eight percent of PD patients had at least 1 plaque. Serum CRP level was greater than the upper limit of the normal range in 52.5% of patients. Compared with PD patients with normal CRP levels, concentrations of such proinflammatory cytokines as IL-1Ra and TNF-sR, Lp(a), and Hcy were increased in PD patients with elevated CRP levels. However, no differences in plasma fibrinogen and intact parathyroid hormone levels were found between PD patients with increased and normal CRP levels. In a multiple regression model, age, male sex, CRP level, and Lp(a) level were independent predictors of IMT. Similarly, male sex, CRP level, Lp(a) level, and Hcy level were independent correlates of PS.

CONCLUSION

This study suggests that Lp(a) and Hcy levels and male sex, and especially CRP level, have an important role in carotid atherosclerosis in PD patients.

Is serum albumin a marker of nutritional status in hemodialysis patients without evidence of inflammation?

Hypoalbuminemia, a strong predictor of morbidity and mortality in hemodialysis patients, can be a consequence of a combination of malnutrition and inflammatory reactions. The purpose of this study was to analyze serum albumin as a marker of nutritional status in maintenance hemodialysis patients with no signs of inflammation. In a cross-sectional study, we selected 40 stable hemodialysis patients with normal levels of C-reactive protein (<0.8 mg/dL). The patients were classified as well nourished (65%) or malnourished (35%) according to the subjective global assessment. No significant differences were observed in serum albumin concentrations (immunoturbidimetric method) between well-nourished (4.3 +/- 0.3 g/dL) and malnourished (4.0 +/- 0.5 g/dL) patients, and the mean values were within the normal range in both groups. Albumin was inversely correlated with age (n=40; r=-0.32; P=0.02) and directly with energy intake (n=28; r=0.43; P=0.04). In this study, serum albumin did not discriminate well-nourished and malnourished hemodialysis patients without evidence of inflammation.

Survival of patients undergoing hemodialysis with paricalcitol or calcitriol therapy

BACKGROUND

Elevated calcium and phosphorus levels after therapy with injectable vitamin D for secondary hyperparathyroidism may accelerate vascular disease and hasten death in patients undergoing long-term hemodialysis. Paricalcitol, a new vitamin D analogue, appears to lessen the elevations in serum calcium and phosphorus levels, as compared with calcitriol, the standard form of injectable vitamin D.

METHODS

We conducted a historical cohort study to compare the 36-month survival rate among patients undergoing long-term hemodialysis who started to receive treatment with paricalcitol (29,021 patients) or calcitriol (38,378 patients) between 1999 and 2001. Crude and adjusted survival rates were calculated and stratified analyses were performed. A subgroup of 16,483 patients who switched regimens was also evaluated.

RESULTS

The mortality rate among patients receiving paricalcitol was 3417 per 19,031 person-years (0.180 per person-year), as compared with 6805 per 30,471 person-years (0.223 per person-year) among those receiving calcitriol (P<0.001). The difference in survival was significant at 12 months and increased with time (P<0.001). In the adjusted analysis, the mortality rate was 16 percent lower (95 percent confidence interval, 10 to 21 percent) among paricalcitol-treated patients than among calcitriol-treated patients. A significant survival benefit was evident in 28 of 42 strata examined, and in no stratum was calcitriol favored. At 12 months, calcium and phosphorus levels had increased by 6.7 and 11.9 percent, respectively, in the paricalcitol group, as compared with 8.2 and 13.9 percent, respectively, in the calcitriol group (P<0.001). The two-year survival rate among patients who switched from calcitriol to paricalcitol was 73 percent, as compared with 64 percent among those who switched from paricalcitol to calcitriol (P=0.04).

CONCLUSIONS

Patients who receive paricalcitol while undergoing long-term hemodialysis appear to have a significant survival advantage over those who receive calcitriol. A prospective, randomized study is critical to confirm these findings.