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

Extracorporeal treatment strategy in acute renal failure

The mortality of acute renal failure remains high (around 50-70%) despite manifold improvements in terms of techniques and equipment for renal replacement therapies as well as patient monitoring and intensive care support. At present, it is not clear if the method chosen for renal replacement therapy, i.e. intermittent hemodialysis or continuous hemofiltration, might impact on the outcome of these patients. Whilst earlier retrospective studies suggested that CVVH might result in better survival and renal recovery in acute patients, recent prospective studies indicated that this may not be the case or, conversely, outcomes may be better with IHD. These studies were, however, not evenly randomised in terms of illness severity or were too small to produce conclusive results. In addition, a meta-analysis of 9 published prospective studies in 692 pts. indicated a similar mortality with CVVH vs. IHD. Some of the studies enrolled for this meta-analysis, however, suffered from methodological and/or randomisation problems, thus this important question remains to date unanswered. Typically, CVVH is chosen for treating patients with hemodynamic instability and volume overload. In such cases, however, CVVH should be performed with a filtrate volume of at least 35 ml/kg body weight per hour as this was shown to be associated with better survival as compared to smaller filtrate volumes. A second controversy exists to date whether the choice of the dialyzer membrane might be of relevance for the outcome of patients with acute renal failure. Earlier studies indicated that the use of biocompatible membranes in these patients may result in improved patient survival and renal recovery. More recently, however, similar studies could not confirm these results. Another meta-analysis of controlled prospective trials (671 patients in 7 separate studies) calculated a relative mortality risk of 1.01 for cuprophan vs. biocompatible membranes. Thus, the choice of the dialyzer membrane should be based on individual assessment rather than treatment bias.

Critical care issues in the patient with chronic renal failure

The metabolic abnormalities associated with chronic renal failure and complications of the dialysis procedure present unique challenges in critical care medicine. Understanding how renal failure impacts the development and management of cardiovascular disease, bleeding tendencies, infection, and malnutrition is necessary to provide optimal care for these patients. The recognition of ESRD as a state of chronic inflammation and increased oxidative stress ultimately should lead to more effective treatment approaches for several of the comorbid conditions common in this patient population.

Comparison of mortality and intermediate outcomes between medicare dialysis patients in HMO and fee for service

End-stage renal disease (ESRD) is the only disease entitlement for Medicare; therefore, most patients with ESRD have Medicare coverage. Patients with ESRD are prohibited by law from enrolling in health maintenance organizations (HMOs), the only group prohibited within Medicare. However, they may remain in an HMO if they enrolled in such a plan before their kidneys failed. Thus, it is possible to compare patients with ESRD in HMOs with those in fee-for-service (FFS) plans. To determine whether mortality, transplantation rates, and intermediate outcomes differed between Medicare ESRD beneficiaries enrolled in HMO versus FFS providers, a retrospective cohort analysis was performed of patients with ESRD from three Health Care Financing Administration data sets containing administrative and outcome information for Medicare ESRD beneficiaries from 1990 to 1998. On December 31, 1998, a total of 278,510 prevalent patients with ESRD were in FFS plans, and 18,332 patients were in HMOs. HMO patients were older and more likely to be white and male and have diabetes mellitus and comorbid cardiovascular conditions than FFS patients. Unadjusted 2-year survival rates were 48.4% and 49.3% for FFS and HMO patients, respectively. In a multivariate model, HMO status had no significant effect on mortality, which was greater with older age, male sex, and white race. In 1998, unadjusted renal transplantation rates were 23.5% and 15.5% for FFS and HMO patients, respectively; age adjustment abrogated the apparent difference. For FFS and HMO patients, adequate hemodialysis was delivered to 72% and 82%, and 56% and 62% had hematocrits greater than the benchmark, respectively. There was no statistical difference in these outcomes in multivariate comparison. In conclusion, care by HMO for patients with an expensive chronic illness can achieve outcomes similar to those for FFS patients. Claims of poorer care and worse outcomes for patients with ESRD enrolled onto an HMO, an argument used to justify continued prohibition against widespread participation by patients with ESRD, are not supported.

Dialysis dose and body mass index are strongly associated with survival in hemodialysis patients

Low dose of hemodialysis (HD) and small body size are independent risk factors for mortality. Recent changes in clinical practice, toward higher HD doses and use of more high-flux dialyzers, suggest the need to redetermine the dose level above which no benefit from higher dose can be observed. Data were analyzed from 45,967 HD patients starting end-stage renal disease (ESRD) therapy during April 1, 1997, through December 31, 1998. Data from Health Care Financing Administration (HCFA) billing records during months 10 to 15 of ESRD were used to classify each patient into one of five categories of HD dose by urea reduction ratio (URR) ranging from <60% to >75%. Cox regression models were used to calculate relative risk (RR) of mortality after adjustment for demographics, body mass index (BMI), and 18 comorbid conditions. Of the three body-size groups, the lowest BMI group had a 42% higher mortality risk than the highest BMI tertile. In each of three body-size groups by BMI, the RR was 17%, 17%, and 19% lower per 5% higher URR category among groups with small, medium, and large BMI, respectively (P < 0.0001 for each group). Patients treated with URR >75% had a substantially lower RR than patients treated with URR 70 to 75% (P < 0.005 each, for medium and small BMI groups). It is concluded that a higher dialysis dose, substantially above the Dialysis Outcomes Quality Initiative guidelines (URR >65%), is a strong predictor of lower patient mortality for patients in all body-size groups. Further reductions in mortality might be possible with increased HD dose.

Infrainguinal endovascular and bypass surgery for critical leg ischemia in patients on long-term dialysis

Lower limb revascularization has been shown to be worthwhile for treatment of critical leg ischemia in uremic patients, but poor results are expected in patients on long-term dialysis. We have retrospectively evaluated the results of a series of 21 consecutive patients on long-term dialysis who underwent 20 infrainguinal bypass graft and 5 endovascular procedures for critical leg ischemia to identify factors contraindicating any infrainguinal revascularization attempt in this patient population. At 2-year follow-up, the patency rate was 74%, leg salvage rate was 85%, and survival rate was 23%, whereas 23% of patients were alive with salvaged leg. Patients on hemodialysis achieved better survival outcome than patients on peritoneal dialysis (p = 0.02). Multivariate analysis showed that low serum level of albumin (p = 0.009; p = 0.005) and coronary artery disease (p = 0.0002; p = 0.001) had an adverse effect on the survival rate and on the rate of patients alive with salvaged leg, respectively. Patients without coronary artery disease achieved an alive-with-salvaged-leg rate at 1- and 2-year follow-up of 68% and 41%, respectively, whereas 12% of patients with coronary artery disease survived with salvaged leg after 1 year, but none of them survived with salvaged leg at 2-year follow-up (p = 0.003). In conclusion, infrainguinal revascularization for lower extremity ischemia in dialysis patients is hardly indicated in the presence of coronary artery disease and severe hypoalbuminemia.

Impact of years of dialysis therapy on mortality risk and the characteristics of longer term dialysis survivors

With improving survival and a decreasing probability of receiving a transplant, patients with end-stage renal disease (ESRD) are more likely to remain on hemodialysis therapy for more years than in the past. This study evaluates the effect of years on dialysis (vintage) on relative risk (RR) for death with and without adjustment for comorbidities and treatment factors. It also compares characteristics of patients on hemodialysis therapy for 7 years or longer with those on hemodialysis therapy for 1 to 7 years. Data were combined from two special US Renal Data System studies, the Case Mix Adequacy Study and Waves 1, 3, and 4 of the Dialysis Mortality and Morbidity Study. Excluding the first year of dialysis, 12,687 patients were studied during a 2-year follow-up, censoring at transplantation or loss to follow-up. Unadjusted analysis (vintage 1 to < 2 years as referent) showed that the risk for death remained nearly the same until the end of year 7 of dialysis therapy, after which the risk decreased significantly. However, with adjustment for demographics, comorbidities, and treatment factors, vintage was significantly associated with increased mortality risk during years 2 to less than 8 (RR = 1.12 to 1.30; P < 0.05). Vintage was independently associated with increased adjusted mortality among patients with and without diabetes until approximately 6 to less than 8 years of dialysis therapy. Patients on dialysis therapy for 7 years or longer were significantly (P < 0.05) more likely to be women, younger, and have lower phosphorus levels, higher hematocrits, and higher delivered dialysis doses. We conclude that adjusted mortality risk does not decrease with years on dialysis therapy, and modifiable factors deserve greater attention to improve survival among patients with ESRD with and without diabetes treated by hemodialysis.

Urea kinetics during sustained low-efficiency dialysis in critically ill patients requiring renal replacement therapy

Continuous renal replacement therapies have practical and theoretical advantages compared with conventional intermittent hemodialysis in hemodynamically unstable or severely catabolic patients with acute renal failure (ARF). Sustained low-efficiency dialysis (SLED) is a hybrid modality introduced July 1998 at the University of Arkansas for Medical Sciences that involves the application of a conventional hemodialysis machine with reduced dialysate and blood flow rates for 12-hour nocturnal treatments. Nine critically ill patients with ARF were studied during a single SLED treatment to determine delivered dialysis dose and the most appropriate model for the description of urea kinetics during treatment. Five patients were men, mean Acute Physiology and Chronic Health Evaluation (APACHE) II score was 28.9 and mean weight was 92.5 kg. Kt/V was determined by the reference method of direct dialysate quantification (DDQ) combined with an equilibrated postdialysis plasma water urea nitrogen (PUN) concentration and four other methods that were either blood or dialysate based, single or double pool, or model independent (whole-body kinetic method). Solute removal indices (SRIs) were determined from net urea removal and urea distribution volume supplied from DDQ (reference method) and by mass balance using variables supplied from blood-based formal variable-volume single-pool (VVSP) urea kinetic modeling. Equivalent renal urea clearances (EKRs) were calculated from urea generation rates and time-averaged concentrations for PUN based on weekly mass balance with kinetic variables supplied by either DDQ (reference method) or formal blood-based VVSP modeling. Mean Kt/V determined by the reference method was 1.40 and not significantly different when determined by formal VVSP modeling, DDQ using an immediate postdialysis PUN, or the whole-body kinetic method. Correction of single-pool Kt/V by a Daugirdas rate equation did not yield plausible results. Mean SRI and EKR by the reference methods were 0.61 and 24.8 mL/min, respectively, and not significantly different when determined by blood-based methods. A single-pool urea kinetic model adequately described intradialytic PUN profiles, indicating that SLED was associated with minimal urea disequilibrium. This was supported by the parity between hemodialyzer and whole-body urea clearances, and the mean postdialytic urea rebound of 4.1% (P = 0.13 versus zero). Additional prospective studies are needed in this setting to define the optimal method for dialysis quantification, targets for azotemic control, and optimal modality of renal replacement therapy. In conclusion, SLED delivers a high dose of dialysis with minimal associated urea disequilibrium and can be quantified by Kt/V, SRI, and EKR from blood-based methods using single-pool urea kinetic models.

Peritoneal and hemodialysis: II. Mortality risk associated with initial patient characteristics

BACKGROUND

Patients initiating with peritoneal dialysis (PD) have favorable clinical conditions compared with hemodialysis (HD) patients, which may contribute to the varying results found in studies of mortality across the two therapies.

METHODS

National incidence data of end-stage renal disease patients from 1995 to 1997 were used, excluding the first 90 days of treatment and including all patients who were on either PD or HD on day 91. Patients were then followed for a one-year period. A Cox proportional hazards regression analysis was used, separating diabetics and non-diabetics, and two statistical models were applied. Model 1 included race, gender, age, initial modality, and incidence year as explanatory variables. Model 2 added body mass index (BMI), initial levels of serum albumin, creatinine, and blood urea nitrogen.

RESULTS

Age was most highly associated with mortality, followed by biochemical variables, BMI, gender, and dialysis modality. In diabetics, the hazard ratio (HR) from Model 1 indicated no difference [1.046, 95% confidence limits (CL) 0.989-1.105; P> 0.1, HD was the reference] in mortality between PD and HD, while Model 2 demonstrated that PD patients had a 13.4% (1.134, CL 1.072-1.100, P < 0.0001) higher chance of death. In non-diabetics, hazard ratios (HRs) from Models 1 and 2 indicated that PD patients had a 23.5% (0.765, 0.722-0.812, P < 0.0001) and 11.9% (0.881, 0.30-0.935, P < 0.0001), respectively, lower likelihood of death than HD patients.

CONCLUSION

Our study indicates that the results changed depending on the analytical methods used. We recommend that, due to the unequally distributed clinical conditions of patients at initiation, comparisons of mortality outcomes between dialysis modalities should be made with caution.

Peritoneal and hemodialysis: I. Differences in patient characteristics at initiation

BACKGROUND

Comparisons of mortality outcomes between peritoneal dialysis (PD) and hemodialysis (HD) patients have shown varying results, which may be caused by the unequally distributed clinical conditions of patients at initiation. To address this issue, we evaluated the clinical characteristics of 105,954 patients at the initiation of PD and HD, using the U.S. national incidence data on treated end-stage renal disease from the Medical Evidence Form, 1995 to 1997.

METHODS

A general linear model was used to analyze differences of age, albumin, creatinine, blood urea nitrogen (BUN), and hematocrit; categorical data analysis to evaluate body mass index (BMI), grouped into four categories: < 19, 19-25 (< 25), 25-30 (< 30), and 30+; and logistic regression to assess the likelihood of initiating PD versus HD. Diabetics (DM) were analyzed separately from non-diabetics (NDM). Explanatory variables in the logistic regression included incidence year, race, gender, age, BMI, albumin, creatinine, BUN, and hematocrit. Race included white and black. Age was categorized into four groups: 20-44, 45-64, 65-74, and 75+.

RESULTS

At the initiation of dialysis PD patients were approximately 6 years younger (P < 0.0001) than HD patients. PD patients also had higher (P < 0.0001) albumin (+0.35 g/dL for DM and +0.23 g/dL for NDM) and hematocrit (+1.64% for DM and +1.71% for NDM) levels, and lower (P < 0.04) BUN (-8.75 mg/dL for DM and -5.24 mg/dL for NDM) and creatinine (-0.51 mg/dL for DM and -0.23 mg/dL for NDM) levels than HD patients. Whites had a higher (P < 0.0001) likelihood of starting PD than blacks, and patients with BMI <19 had a lower (P < 0.0001) chance of beginning on PD.

CONCLUSION

PD patients had favorable clinical conditions at the initiation of dialysis, which should be taken into consideration when comparing dialysis outcomes between the two modalities.

Predicting 30-minute postdialysis blood urea concentrations using the stop dialysate flow method

The stop dialysate flow (SDF) method has been the recommended method of postdialysis urea sampling by the Scottish Renal Association since November 1998. However, this method does not lend itself to calculation of Kt/V using currently favored formulas, which require either a 30-minute postdialysis sample or a 20-second "slow flow" sample. We, therefore, derived a formula that uses a 5-minute postdialysis urea sample using the SDF method to estimate the urea concentration at 30 minutes. Blood samples were obtained from 70 hemodialysis patients immediately before dialysis and at 0, 5, and 30 minutes postdialysis. Half of the patients from each unit were randomly selected to form the linear regression equation: Estimated 30-minute urea concentration = 1.06 x (5-minute urea concentration) + 0.22. This equation was validated using the data from the remaining 35 patients. This showed a very close correlation between measured and estimated urea concentration at 30 minutes (R2 = 0.97), and a Bland-Altman plot confirmed this close relationship. The sensitivity, specificity, positive, and negative predictive values of this equation were high when used to estimate 30-minute urea reduction ratio (URR) greater than 65% (100%, 85.7%, 97%, and 100%, respectively) and 30-minute Kt/V greater than 1. 2 (96.7%, 100%, 100%, and 80%, respectively). The coupling of the SDF method with the above formula combines the advantages of simple and reproducible postdialysis blood sampling with an accurate estimation of the 30-minute postdialysis blood urea concentration, URR, and Kt/V. This method should be a useful tool for comparative audit of hemodialysis adequacy.

Changes of serum albumin and C-reactive protein are related to changes of interleukin-6 release by peripheral blood mononuclear cells in hemodialysis patients treated with different membranes

Protein malnutrition, a condition associated with an albumin concentration less than 3.5 g/dL, has been shown to be a major risk factor for increased mortality in hemodialysis patients. The aim of this cross-over study was to evaluate the relationship between the type of membrane adopted and serum albumin changes by measuring peripheral blood mononuclear cells (PBMC) interleukin-6 (IL-6) release, serum albumin, and plasma concentrations of C-reactive protein (CRP) in 18 patients dialyzed with different membranes. During the study, all patients were dialyzed with cuprophan (CU), synthetically modified cellulosic (SMC) membrane (a new cellulosic membrane with lesser complement activation), and cellulose diacetate (CD) membrane, and have served as their own controls. IL-6 spontaneous release by PBMC resulted after 3 months of SMC (436.2 +/- 47.4 pg/mL) significantly (P < 0.05) reduced as compared with CU (569.3 +/- 24.5 pg/mL). This effect was more evident after 6 months of dialysis with SMC (220 +/- 35.3 pg/mL, P < 0.01 versus CU and versus 3 months of SMC). The passage to CD membrane was followed by a progressive new increase in the IL-6 PBMC release (332.3 +/- 30.7 after 3 months, and 351.2 +/- 35.8 pg/mL after 6 months, respectively) that, however, remained significantly (P < 0.05) lower than CU. The behavior of CRP plasma levels resembled that of IL-6 PBMC release (23.3 +/- 4.7 in CU, 11.0 +/- 2.1 after 3 months in SMC, and 7.9 +/- 1.5 after 6 months in SMC, respectively). IL-6 release values were positively correlated with circulating levels of CRP (r = 0.3264, P < 0.002). Serum albumin increased after 6 months of dialysis with SMC membranes (3.25 +/- 0.09 g/dL in CU and 3.64 +/- 0.07 g/dL in SMC, P < 0.05). When the patients were switched to CD, serum albumin showed a slight, though not statistically significant, decrease. Serum albumin concentrations negatively correlated with both IL-6 release values (r = -0.247, P < 0.05) and CRP plasma levels (r = -0.433, P < 0.001). In conclusion, our data clearly show that a significant relationship exists between biocompatibility of the membranes and serum albumin changes; serum albumin levels, in fact, are negatively correlated with the PBMC spontaneous IL-6 release values and CRP circulating levels.

Hypoalbuminemia and risk of death in pediatric patients with end-stage renal disease

BACKGROUND

Although serum albumin is a marker for malnutrition and associated with a higher mortality in adult patients with end-stage renal disease (ESRD), the risk of death associated with serum albumin is unknown in pediatric patients with ESRD. We evaluated the association between serum albumin and death among pediatric patients initiating dialysis.

METHODS

Data from the United States Renal Data System (USRDS) were used to identify all patients under the age of 18 who initiated dialysis between January 1, 1995 and December 31, 1998. Using the Cox proportional hazards models, the association between serum albumin obtained 45 days prior to dialysis initiation and death was estimated, controlling for demographic factors, dialysis modality, and anthropometric measures.

RESULTS

Of 1723 patients included in the analysis, there were 93 deaths over 2953 patient-years of observation. The multivariate analysis demonstrated that each -1 g/dL difference in serum albumin between patients was associated with a 54% higher risk of death [adjusted relative risk (aRR), 1.54; 95% confidence interval (CI), 1.15 to 1.85; P=0.002]. This was independent of glomerular causes for their ESRD and other potential confounding variables.

CONCLUSIONS

Pediatric patients initiating dialysis with hypoalbuminemia are at a higher risk for death. This finding persists after adjusting for glomerular causes for ESRD and other potential confounding variables. Low serum albumin at dialysis initiation is an important marker of mortality risk in pediatric ESRD patients.

Nutritional status in the HEMO Study cohort at baseline. Hemodialysis

The nutritional status of the first 1,000 patients randomized into the Hemodialysis (HEMO) Study was analyzed at baseline when they received their typical dialysis dose (equilibrated Kt/V = 1.30 +/- 0.22) and dialysis membrane. This is the largest study to date of the nutritional status of chronic hemodialysis patients. The mean (+/- SD) values for these parameters included a serum albumin level of 3.65 +/- 0.38 g/dL, a dietary energy intake of 22.9 +/- 8.4 kcal/kg/day, a dietary protein intake of 0.93 +/- 0.36 g/kg/day, and a double pool normalized protein catabolic rate (enPCR) of 1.00 +/- 0.25 g/kg/day. The percentage of patients below HEMO Study nutritional standards of care included 29% of patients with a serum albumin level less than 3.5 g/dL, 76% of patients with a dietary energy intake less than 28 kcal/kg/day, 61% of patients with a dietary protein intake less than 1.0 g/kg/day, and 52% of patients with an enPCR of less than 1.0 g/kg/day. There was a strong correlation between dietary protein intake and dietary energy intake (r = 0.74, P < 0.0001). Significant correlations were also evident between serum albumin and double pool PCR and between dietary protein intake and double-pool PCR. Kt/V and membrane flux were not predictive of baseline dietary protein intake, dietary energy intake, or serum albumin level. Thus, a majority of patients in the HEMO Study had protein and energy intake levels and enPCR levels that were below National Kidney Foundation Kidney Dialysis Outcome Quality Improvement (NKF-K/DOQI) guidelines.

Comorbidity and other factors associated with modality selection in incident dialysis patients: the CHOICE Study. Choices for Healthy Outcomes in Caring for End-Stage Renal Disease

Case-mix factors influence both the selection of dialysis modality and outcomes in end-stage renal disease (ESRD). A detailed characterization of the case-mix differences between peritoneal dialysis (PD) and hemodialysis (HD) patients at the onset of dialysis therapy has not been performed, despite the importance of accounting for baseline differences in future comparisons of outcomes across modality groups. We compared baseline characteristics of 279 PD and 759 HD patients enrolled in the Choices for Healthy Outcomes in Caring for End-Stage Renal Disease (CHOICE) Cohort Study, a prospective study of incident dialysis patients. Comorbidity was assessed using the Index of Coexistent Diseases (ICED), consisting of a medical record review of 19 medical conditions and an observer-based assessment of 11 physical functions. ICED scores range from 0 to 3, with higher levels reflecting more severe comorbidity. Comorbidity was less severe in PD patients than in HD patients: the proportions of patients with ICED 0-1, ICED 2, and ICED 3 were 52%, 26%, and 22%, respectively, among the PD patients and 30%, 39%, and 31%, respectively, among the HD patients (P < 0.001). After controlling for all other factors, the differences in comorbidity remained significant. As compared with patients with ICED 0-1, the odds of being treated with PD for patients with ICED 2 and ICED 3 were less (odds ratio [OR] and 95% confidence intervals) 0.31 (0.17 to 0.56) and 0.50 (0.28 to 0.90), respectively. The number and severity of comorbid conditions at the onset of ESRD is significantly lower in patients choosing PD, independent of other factors influencing modality selection. The increased survival of PD patients reported in recent studies may simply reflect the self- or physician-directed selection of healthier patients to PD. Adjustment for case-mix differences in patients treated with PD versus HD is essential to the assessment of the independent effect of the dialysis modality on outcomes.

Body mass index as a predictor of continued survival in older chronic dialysis patients

OBJECTIVE

To investigate the contribution of body mass index (BMI) to mortality over 11 years of follow-up in a prevalent sample of dialysis patients aged 60+.

DESIGN

Multivariate Cox proportional hazards regression analysis.

SETTING

Multicenter stratified random sample of black and white older chronic dialysis patients in a southeastern state.

SUBJECTS

316 patients on hemodialysis (HD) and peritoneal dialysis (PD).

MAIN OUTCOME MEASURE

Continued survival from baseline interview in 1988 to June 1999.

RESULTS

Adjusting for age, primary diagnosis of diabetes, cardiovascular comorbidity, HD/PD therapy, and patient-reported functional impairment, the interaction of baseline BMI with race and gender was associated with older patients' risk of mortality. Black females, black males, and white males with higher BMI had a reduced risk of mortality, while no protective effect of higher BMI was found for white females. Patients with cardiovascular comorbidity and greater functional impairment at baseline had increased mortality risk. BMI was not significantly correlated with serum albumin or functional impairment.

CONCLUSION

BMI, a simple anthropometric measure that provides a marker of nutritional status, interacts with race and gender to predict long-term survival in older dialysis patients. The association of survival with dialysis adequacy, nutritional indicators, and cardiovascular status in black and white dialysis patients is an important area of study.

Survival Comparison between Hemodialysis and Peritoneal Dialysis Based on Matched Doses of Delivered Therapy

ABSTRACT. Several studies have recently confirmed that hemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD) survival is highly associated with delivered therapy Kt/Vurea. A direct comparison of equivalently dosed CAPD and HD has not previously been performed. A total of 968 incident HD patients at the Regional Kidney Disease Program from 1987 to June 1995 were studied, and these results were compared with those of the Canadian-United States prospective trial (CANUSA) consisting of 680 incident CAPD patients from September 1990 to December 31, 1992, with follow-up through December 31, 1993. All patients had quantitation of urea nitrogen for a total delivered dialysis session. On HD, in vivo, 2-pool, pre- and post-blood urea nitrogen kinetic modeling was performed with residual renal function determined every 6 mo. Patients were characterized by age, gender, race, renal diagnosis, and comorbid conditions. A Cox proportional hazards model was used to evaluate the effect of the individual comorbid conditions and the effect of dialysis therapy in the time-dependent method. The mean total Kt/V, both residual renal function and dialytic therapy in the HD patients, was 1.59. The CANUSA-delivered weekly Kt/V was 2.38 at the beginning of the baseline period and 1.99 after 24 mo of follow-up. When the peak concentration hypothesis was used, a Kt/V of 1.59 on HD was equivalent to a weekly CAPD dose of 2.1 to 2.2. A 1-unit increase in Kt/V was associated with 7% lower risk of death on HD and with a similar 8% lower risk of death while on CAPD. Patients with diabetes aged 46 to 60 yr had virtually identical 2-yr survival estimates on HD (83 to 90%), compared with CAPD (83 to 89%), with Kt/V ranges from 0.84 to 1.70 in HD and from 1.6 to 2.2 weekly Kt/V on peritoneal dialysis. Comparisons between HD and CAPD in older patients with diabetes yielded comparable results. Patient survival is highly influenced by delivered dialysis in both HD and peritoneal dialysis. Carefully matching of the therapies with delivered Kt/V demonstrates little differences in the survival outcome of HD and peritoneal dialysis patients, in contrast to some previous reports.

An introduction to epidemiology and biostatistics and issues in interpretation of studies

Epidemiology is the basic medical science that focuses on the distribution and determinants of disease frequency in human populations. An understanding of the tools of epidemiology is helpful in defining the limitations of medical research and evaluating the conclusions of studies. This is the first in a series of three articles whose objective will be to present the basic concepts of epidemiology and biostatistics. Examples of each of the tools and limitations discussed from studies of patients with end-stage renal disease (ESRD) will be presented to provide the reader with a practical application of the concepts. This series of articles will help the reader to weigh methods and study designs to understand the appropriate conclusions that may be drawn from any data.

Inflammation, Malnutrition, and Cardiac Disease as Predictors of Mortality in Hemodialysis Patients

ABSTRACT. Various studies suggest a strong association between nutrition and clinical outcome in hemodialysis (HD) patients. Several morbidity factors that per se increase the risk of a poor outcome, such as cardiovascular disease (CVD) and inflammation, may also cause malnutrition. Among laboratory parameters used to assess nutritional status, serum albumin appears to be a particularly strong predictor of morbidity and mortality. This study assessed the importance of nutritional status and inflammation and other comorbidity factors as predictors of mortality in HD patients. Nutritional status was evaluated in 128 HD patients by subjective global nutritional assessment (SGNA) and by measuring several anthropometric markers (actual body weight, percentage of actual body weight to desirable body weight, midarm muscle circumferences, triceps skinfold thickness), and serum albumin, plasma insulin such as insulin growth factor-1 and as a marker of inflammation, serum C-reactive protein (s-CRP) levels. The mortality during the next 36 mo was analyzed in relation to age, gender, CVD, SGNA, serum albumin, CRP, and several other factors by Kaplan-Meier analysis multivariate. Cox proportional hazard analysis was used to identify independent predictors of mortality. After 36 mo, 58 patients were still on HD treatment, 57 patients (45%) had died while receiving treatment, and 13 had received a kidney transplant. The main cause of death was CVD (58%), followed by infection (18%); malnutrition/cachexia was a rare direct cause of death (5%). Kaplan-Meier analysis showed that age, female gender, CVD, diabetes, SGNA, all anthropometric parameters, serum albumin, plasma insulinlike growth factor-1, and s-CRP were significant predictors of mortality. Analysis by the Cox model showed that age, gender, CVD, nutritional status (SGNA), and CRP were independent predictors of mortality at 36 mo. A low albumin level was not an independent predictor, although it was strongly associated with a reduced survival rate in the Kaplan-Meier analysis. Inflammation, malnutrition, and CVD appeared to contribute to increased mortality in a stepwise manner. The mortality at 36 mo was 0% when none of these complications was present, whereas the mortality was 75% in those patients with all three risk factors present at baseline. It is concluded that in addition to malnutrition and comorbidities (CVD, diabetes mellitus), inflammation (elevated s-CRP) is a significant independent risk factor for mortality in HD patients. Inflammation, malnutrition, and CVD appear to be interrelated, each additionally contributing to the high mortality in these patients.

Role of soluble receptors for tumor necrosis factor alpha in the development of hypoalbuminemia in hemodialysis patients

BACKGROUND

Hypoalbuminemia is a significant predictor of mortality in patients on hemodialysis (HD). The cause of hypoalbuminemia in HD patients, however, remains to be clarified. Recent studies have demonstrated that high blood concentrations of soluble receptors for tumor necrosis factor (sTNFRs) are associated with malnutrition in a variety of diseases and that the blood sTNFRs concentrations are elevated in HD patients.

METHODS

The serum concentrations of tumor necrosis factor alpha, sTNFR (p55 and p80), and interleukin (IL) 6 were measured in 21 HD patients with low (equal to or less than 3.6 g/dl) and in 19 HD patients with normal (equal to or more than 4.0 g/dl) concentrations of serum albumin who were free from acute infection, malignancy, collagen diseases, liver diseases, or surgery. The correlation between these parameters and the degree of hypoalbuminemia was examined.

RESULTS

The serum concentrations of sTNFR p80 and IL-6 were significantly higher in patients with hypoalbuminemia as compared with those with normoalbuminemia (sTNFR p80: 47.4 +/- 4.7 vs. 35.3 +/- 2.1 ng/ml, p < 0.05; IL-6: 10.8 +/- 2.0 vs. 6.3 +/- 0.5 pg/ml, p < 0.05). In contrast, there was no difference in the serum concentrations of tumor necrosis factor alpha and sTNFR p55 between the two groups. Multivariate regression analysis showed that sTNFR p80 but not IL-6 significantly influenced the serum albumin concentrations. There were no significant differences in body mass index, serum total cholesterol, and normalized protein catabolic rate between the two groups.

CONCLUSIONS

Our results suggest the development of hypoalbuminemia in some HD patients who do not have any obvious cause of hypoalbuminemia and that high concentrations of sTNFR p80 might contribute to the development of hypoalbuminemia in patients on long-term HD.

Dialysis and nutrition practices in Korean hemodialysis centers

OBJECTIVE

Survey the dialysis practices and nutritional status-related patient characteristics.

DESIGN

Cross-sectional survey.

SETTING

Twenty-eight randomly selected Korean hemodialysis facilities.

METHODS

Medical record review of 140 randomly selected patients in 28 Korean dialysis facilities. The Student t test and chi-square tests were used to compare facility types and locations.

RESULTS

The mean number of dialysis treatments per week was 2.7 +/- 0.4. Mean dialysis treatment length was 253 +/- 27.5 minutes. Rural dialysis centers reported fewer treatments per week and shorter dialysis treatment times than did urban centers but, otherwise, there were few differences by either location (urban v rural) or by facility type (hospital affiliated v freestanding facility). The mean age of the patients surveyed by record review was 51 +/- 14 years, and 59% of the patients were men. The primary causes of end-stage renal disease were chronic glomerulonephritis, hypertension, and diabetes. Average vintage of dialysis was 53 +/- 46 months. Adequacy of dialysis was usually assessed by using clinical judgment; urea kinetic modeling and urea reduction ratios were used less frequently. Patients' mean body mass index was 20.7 +/- 2.3, which was at the lower end of the healthy range of 18.5 to 25, and most (93%) of their weights had been stable over the previous 6 months. Their mean serum albumin level was 4.0 +/- 0.4 g/dL. Forty-two percent of patients used iron supplements and 68% of them received erythropoietin treatment. However, their mean hematocrit levels were only 25.9% +/- 4.2%, suggesting that iron supplements were underused or erythropoietin doses were lower than optimal. Virtually all patients (94%) had received initial diet instruction but few (6%) received follow-up nutrition counseling.

CONCLUSION

Greater attention to dialysis adequacy, hematocrit levels, nutrition assessment, weight monitoring, and diet therapy are recommended.

Pulmonary infectious mortality among patients with end-stage renal disease

BACKGROUND

Infection is the second-leading cause of death among patients with end-stage renal disease (ESRD). This is due in part to advanced age, comorbid conditions, and immune dysfunction observed in uremic states. Although one may hypothesize that pulmonary infectious mortality is higher among patients with ESRD compared with the general population (GP), no such data are currently available.

METHODS

We compared annual pulmonary infectious mortality rates among patients with ESRD to those in the GP. The data were abstracted from the United States Renal Data System and the National Center for Health Statistics, respectively, and were stratified by age, gender, race, and presence or absence of diabetes mellitus (DM). In the GP, primary and multiple cause-of-death analyses were performed to account for potential limitations of the data sources.

RESULTS

Overall, pulmonary infectious mortality rate was 14-fold to 16-fold higher in dialysis patients and approximately twofold higher in renal transplant recipients compared with the GP. After stratification for age, differences between groups decreased but retained their magnitude.

CONCLUSION

Patients with ESRD treated with dialysis have higher pulmonary infectious mortality rates compared with the GP, even after stratification for age, race, and DM. Consequently, this patient population must be considered at high risk for the development of lethal pulmonary infections.

A malnutrition-inflammation score is correlated with morbidity and mortality in maintenance hemodialysis patients

Malnutrition inflammation complex syndrome (MICS) occurs commonly in maintenance hemodialysis (MHD) patients and may correlate with increased morbidity and mortality. An optimal, comprehensive, quantitative system that assesses MICS could be a useful measure of clinical status and may be a predictor of outcome in MHD patients. We therefore attempted to develop and validate such an instrument, comparing it with conventional measures of nutrition and inflammation, as well as prospective hospitalization and mortality. Using components of the conventional Subjective Global Assessment (SGA), a semiquantitative scale with three severity levels, the Dialysis Malnutrition Score (DMS), a fully quantitative scoring system consisting of 7 SGA components, with total score ranging between 7 (normal) and 35 (severely malnourished), was recently developed. To improve the DMS, we added three new elements to the 7 DMS components: body mass index, serum albumin level, and total iron-binding capacity to represent serum transferrin level. This new comprehensive Malnutrition-Inflammation Score (MIS) has 10 components, each with four levels of severity, from 0 (normal) to 3 (very severe). The sum of all 10 MIS components ranges from 0 to 30, denoting increasing degree of severity. These scores were compared with anthropometric measurements, near-infrared-measured body fat percentage, laboratory measures that included serum C-reactive protein (CRP), and 12-month prospective hospitalization and mortality rates. Eighty-three outpatients (44 men, 39 women; age, 59 +/- 15 years) on MHD therapy for at least 3 months (43 +/- 33 months) were evaluated at the beginning of this study and followed up for 1 year. The SGA, DMS, and MIS were assessed simultaneously on all patients by a trained physician. Case-mix-adjusted correlation coefficients for the MIS were significant for hospitalization days (r = 0.45; P < 0.001) and frequency of hospitalization (r = 0.46; P < 0.001). Compared with the SGA and DMS, most pertinent correlation coefficients were stronger with the MIS. The MIS, but not the SGA or DMS, correlated significantly with creatinine level, hematocrit, and CRP level. During the 12-month follow-up, 9 patients died and 6 patients left the cohort. The Cox proportional hazard-calculated relative risk for death for each 10-unit increase in the MIS was 10.43 (95% confidence interval, 2.28 to 47.64; P = 0.002). The MIS was superior to its components or different subversions for predicting mortality. The MIS appears to be a comprehensive scoring system with significant associations with prospective hospitalization and mortality, as well as measures of nutrition, inflammation, and anemia in MHD patients. The MIS may be superior to the conventional SGA and the DMS, as well as to individual laboratory values, as a predictor of dialysis outcome and an indicator of MICS.

Association between renal insufficiency and malnutrition in older adults: results from the NHANES III

BACKGROUND

The extent to which relevant confounding variables influence the recognized association between renal insufficiency and malnutrition is not known. This study examined whether renal insufficiency was associated with malnutrition, independent of relevant demographic, social, and medical conditions in noninstitutionalized adults 60 years of age and older.

METHODS

Participants (5248) in the United States Third National Health and Nutrition Examination Survey (NHANES III, 1988 to 1994), a cross-sectional study, were examined in a multivariate logistic regression model. Participants were stratified into three groups of glomerular filtration rate (GFR) by serum creatinine. Dietary and nutritional factors were estimated from 24-hour dietary recall, biochemistry measurements, anthropometry, and bioelectrical impedance. Participants were malnourished if they demonstrated at least three of the following five criteria: (1) serum albumin < or =37 g/L, (2) male weight < or =63.9 kg, female weight < or =51.8 kg, (3) serum cholesterol <4.1 mmol/L, (4) energy intake <15 kcal/kg/day, and (5) protein intake <0.5 g/kg/day.

RESULTS

A GFR <30 mL/min/1.73 m(2) was present in 2.3% of men and 2.6% of women; these participants demonstrated low energy and protein intake and higher serum markers of inflammation. Thirty-one percent of individuals with malnutrition demonstrated a GFR <60 mL/min/1.73 m(2). In multivariate analysis, a GFR <30 mL/min/1.73 m(2) was independently associated with malnutrition [odds ratio 3.6 (2.0 to 6.6)] after adjustment for relevant demographic, social and medical conditions.

CONCLUSIONS

It is probable that renal insufficiency is an important independent risk factor for malnutrition in older adults. Malnutrition should be considered, prevented, and treated as possible in persons with clinically important renal insufficiency. These results should be confirmed in a prospective longitudinal cohort study.

Optimizing medical management of patients with pre-end-stage renal disease

Patients with end-stage renal disease have reduced quality of life, high levels of morbidity, and an annual mortality of about 22%. Because the high morbidity and mortality of dialysis patients might be reduced substantially if patients were healthier at the time of initiating renal replacement therapy, this article will present treatment recommendations designed to retard the progression of chronic renal disease, to optimize the medical management of comorbid medical conditions, such as cardiovascular disease, diabetes, and lipid disorders, and to reduce the complications of renal insufficiency, including hypertension, anemia, hyperparathyroidism, and malnutrition. Given the lack of prospective clinical studies in this area, these recommendations are derived from consensus standards for managing dialysis patients or patients with cardiovascular disease, hypertension, diabetes, and lipid disorders, and from expert opinion derived from laboratory investigations of pathophysiology and relevant experimental disease models.

Improving survival of octogenarian patients selected for haemodialysis

BACKGROUND

The incidence of end-stage renal disease (ESRD) among patients over the age of 80 has nearly tripled in the last decade, making the 'old-old' the fastest growing ESRD demographic group. Despite this, very little information is available on the characteristics and survival of patients who initiate haemodialysis (HD) after reaching this age.

METHODS

We performed a retrospective study on all patients who entered an outpatient HD programme after the age of 80, from January 1988 to September 1998. A total of 106 charts were reviewed from a single nephrology practice group. Eleven patients were excluded due to incomplete data. The survival probability was calculated using the Kaplan-Meier method.

RESULTS

The characteristics of 95 patients were as follows: mean age at initiation of dialysis, 83.7 years; female, 50.5%; Caucasian, 40.0%, African-American, 30.0%; Hispanic, 10.0%; Asian, 4.3%; polytetrafluorethylene grafts, 80.0%; primary fistulas, 5.6%; tunnelled catheters, 5.6%; mean established Kt/V, 1.68; urea reduction ratio (URR), 0.74; estimated dry weight (EDW), 60.3 kg. ESRD was attributed to hypertension in 37%, diabetes in 22% and analgesic use in 8%. The 1-, 2- and 5-year survival probability of the entire group was 82.6+/-4.0%, 64.0+/-5.6%, and 19.6+/-6.0%, respectively. The median survival was 29 months. When comparing survival probability of patients who were in the highest quartiles of URR and EDW to those in the lowest quartile there was no discernible difference. However, the 2-year survival probability of patients initiated after January 1, 1995 (76.9+/-8.4) was significantly better than those initiated from 1988-1994 (47.8+/-6.5; P<0.05).

CONCLUSIONS

From analysis of this cohort, we conclude that: (i) elderly patients selected for outpatient HD programmes have substantially better survival than previously reported; (ii) Kt/V does not correlate with survival in this demographic group; and (iii) contemporary dialysis practice is associated with better likelihood of survival of elderly patients in outpatient HD programmes.

Association between prevalent care process measures and facility-specific mortality rates

BACKGROUND

Medical communities often develop practice guidelines recommending certain care processes intended to promote better clinical outcome among patients. Conformance with those guidelines by facilities is then monitored to evaluate care quality, presuming that the process is associated with and can be used reliably to predict clinical outcome. Outcome is often monitored as a facility-specific mortality rate (SMR) standardized to the mix of patients treated, also presuming that inferior outcome implies a suboptimal process. The U.S. Health Care Financing Administration monitors three practice guidelines, called Core Indicators, in dialysis facilities to assist management of its end-stage renal disease program: (1) patients' hematocrit values should exceed 30 vol%, (2) the urea reduction ratio (URR) during dialysis should equal or exceed 65%, and (3) patients' serum albumin concentrations should equal or exceed 3.5 g/dL.

METHODS

The associations of a facility-specific SMR were evaluated with the fractions of hemodialysis patients not conforming to (that is, at variance with) the Core Indicators during three successive years (1993 to 1995) in large numbers of facilities (394, 450, and 498) using one-variable and multivariable statistical models. Three related strategies were used. First, the association of the SMR with the fraction of patients not meeting the guideline was evaluated. Second, each facility was classified by whether its SMR exceeded the 80% confidence interval above 1.0 (worse than 1.0, Group 3), was less than the interval below 1.0 (better than 1.0, Group 1), or was within the interval (Group 2). The fraction of those patients who did not meet the Indicator guidelines was then evaluated in each group. Third, the ability of variance from Indicator guidelines to predict into which of the three SMR groups a facility would be categorized was evaluated.

RESULTS

SMR was directly correlated with variance from the Indicator guidelines, but the strengths of the associations were weak particularly for the hematocrit (R(2) = 2.2%, 5.6, and 2.2 for each of the 3 years) and URR Indicators (R(2) = 2.6, 0.6, 3.3). It was stronger for the albumin Indicator (R(2) = 11.6, 20.4, 21.8). The fractions of patients falling outside of the Indicator guidelines tended to be higher in the highest SMR group. The groups were not well separated, however, particularly for the hematocrit and URR Indicators, and there was substantial overlap between them. Finally, although the likelihood that a facility would be a member of the high or low SMR group was associated with fractional variance from Core Indicator guidelines, the strengths of association were weak, and the probability that a facility would be a member of the high or low group could not be easily distinguished from the probability that it would be a member of the middle group.

CONCLUSIONS

While there were statistical associations between SMR and the fraction of patients in facilities who were at variance with these guidelines, they were weak and variances from the guidelines could not be used reliably to predict high or low SMR. Such findings do not imply that measures reflecting anemia, dialysis dose, or medical processes that influence serum albumin concentration are irrelevant to the quality of care. They do suggest, however, that more attention needs be paid to these and other associates and causes of mortality among dialysis patients when developing care process indicator guidelines.

Anorexia in end-stage renal disease: pathophysiology and treatment

Anorexia is a frequent complication of uraemic syndrome, which contributes to malnutrition in dialysis patients. Uraemic anorexia has been associated with many factors. This paper reviews the current knowledge about mechanisms responsible for uraemic anorexia, the treatments and new drugs used to control the loss of appetite. Traditionally, anorexia in dialysis patients has been considered as a sign of uraemic toxicity, therefore, two hypotheses have been proposed, the 'middle molecule' and 'peak-concentration' hypotheses, both of which are still unproved. Recently, our group proposed the tryptophan-serotonin hypothesis, which is based on a disorder in the amino acid profile acquired in the uraemic status. This is characterised by low concentrations of large neutral and branched chain amino acids (LNAA/BCAA) in the cerebrospinal fluid. This situation permits a high level of tryptophan transport across the blood-brain barrier, causing an increase in the synthesis of serotonin (responsible for appetite inhibition). There are two main treatment targets for anorexia in dialysis patients. The first is to decrease the free plasma tryptophan concentration and transport across the blood brain barrier to the cerebrospinal fluid, thus decreasing the intracerebral serotonin levels. Nutritional formulae enriched with LNAA and BCAA have this effect. Secondly, plasma levels of cytokines with cachectin effect (TNF-alpha), should be decreased. This also induces a decrease in LNAA and BCAA levels. In this group are megestrol acetate, anti-TNF-alpha antibodies, thalidomide, pentoxifyilline, n-3 fatty acids and possibly nandrolone decanoate. Additionally, other targets should be explored including antagonists of cholecystokinin (a potent anorexigen retained by renal failure), analogues of neuropeptide Y (the most potent orexigen), cannabinoids, cyproheptadine, hydrazine sulfate. In conclusion, uraemic anorexia is a complex complication associated with malnutrition, high morbidity and mortality. The pharmacological treatment should address key points in the pathogenesis of uraemic anorexia, reducing intra-cerebral concentration of serotonin with LNAA/BCAA oral diet formulae and the plasma levels of pro-inflammatory molecules. Others forms of treatment should also be explored.

Differential effects of growth hormone therapy in malnourished hemodialysis patients

BACKGROUND

Malnutrition is common in chronic hemodialysis patients and is associated with increased morbidity and mortality. Several factors such as metabolic acidosis, hyperparathyroidism, and insulin as well as growth hormone (GH) resistance may lead to enhanced protein catabolism. Recombinant human growth hormone (rhGH) has been proposed as treatment of malnutrition because of its anabolic effects.

METHODS

In the present placebo-controlled, double blind study, the effects of three months of rhGH therapy on nutritional and anthropometric parameters, on bone metabolism and bone mineral density (BMD), as well as on polymorphonuclear leukocyte (PMNL) function and quality of life (QoL) were evaluated in 19 malnourished hemodialysis patients (10 females and 9 males) with a mean age of 59.3 +/- 13.4 years. RhGH (0.125 IU/kg) was given three times a week during the first four weeks and 0.25 IU/kg thereafter three times a week after each dialysis session.

RESULTS

Insulin-like growth factor I (IGF-I) concentration rose significantly from 169.2 +/- 95.6 ng/mL to 262.9 +/- 144.4 ng/mL (p< 0.01) in the group receiving rhGH. Albumin, prealbumin, transferrin, cholesterol, high-density lipoprotein (HDL) cholesterol, cholinesterase, predialytic creatinine, and blood urea nitrogen showed no significant changes during the three months in both groups. Total body fat (%TBF) was slightly reduced after three months (P = NS) in the patients receiving GH, whereas lean body mass (LBM) remained stable during therapy. Procollagen I carboxy terminal peptide (PICP), a marker of bone formation, increased significantly after three months from 250.1 +/- 112.6 to 478.5 +/- 235.2 microg/L (P < 0.01) in the GH-treated patients, whereas parameters of bone resorption like telopeptide ICTP showed only a slight increase (50.3 +/- 18.5 vs. 70.0 +/- 39.5 microg/L, P = NS). BMD at the lumbar spine decreased significantly after three months in the treatment group (0.8 +/- 0.17 vs. 0.77 +/- 0.16 g/cm2, P < 0.01), whereas BMD at the femoral neck remained stable in both groups. Phagocytic activity of PMNLs increased significantly after three months of therapy with rhGH, whereas other parameters of PMNL function were not affected by GH. QoL was slightly improved in the GH treated group, but decreased markedly in the placebo group.

CONCLUSIONS

Three months of treatment with rhGH in malnourished patients on chronic hemodialysis causes a significant increase in IGF-I levels without significant changes in nutritional and anthropometric parameters. In contrast, bone turnover was enhanced with an initial decrease in BMD at the lumbar spine, and phagocytic activity of PMNLs was increased.

Comorbidity assessment using the Index of Coexistent Diseases in a multicenter clinical trial

BACKGROUND

The Hemodialysis (HEMO) Study is a multicenter trial designed to determine whether hemodialysis dose and membrane flux affect survival. Comorbid conditions are also important determinants of survival, and thus, an accurate and reliable method to assess comorbidity was required. Comorbidity was being assessed at baseline and annually in the HEMO Study using the Index of Coexistent Disease (ICED). We describe the instrument, its implementation in the HEMO Study, and the results of comorbidity assessment in the first 1000 randomized patients in the trial.

METHODS

The ICED aggregated the presence and severity of 19 medical conditions and 11 physical impairments within two scales: the Index of Disease Severity (IDS) and the Index of Physical Impairment (IPI). The final ICED score was determined by an algorithm combining the peak scores for the IDS and IPI. The range of the ICED was from 0 to 3, reflecting increasing severity.

RESULTS

Study personnel at 15 clinical centers were trained to update and abstract data from the dialysis medical records. Availability of data, measures of construct validity, and measures of reliability were adequate; 99.8% and 60.6% of patients had comorbid conditions in at least one IDS or IPI category, respectively. The distribution of patients by ICED level was 0 (0.2%), 1 (34.9%), 2 (31.2%), and 3 (33.7%). In multivariable analysis, the following factors were significantly associated with more severe comorbidity: older age, diabetes and other causes of renal disease, a lower level of education, employment status (unemployed and retired), longer duration of dialysis, and lower serum creatinine. There was a significant variation in the severity of comorbidity among clinical centers after adjustment for other factors. The R2 of the model was 25.3%, indicating that a substantial proportion of the variation in the ICED was not explained by these factors.

CONCLUSIONS

We conclude that comorbidity assessment using the ICED is feasible in multicenter clinical trials of dialysis patients. There is a large burden of comorbidity in dialysis patients, which is not well explained by the cause of renal disease, demographic, and socioeconomic factors and common clinical and laboratory measurements. These variables should not be considered substitutes for comorbid conditions in case-mix adjustment. Comorbidity assessment is useful to describe the sample population, to improve the precision of the treatment effect, and to use possibly as an outcome measurement.

Association of elevated serum PO(4), Ca x PO(4) product, and parathyroid hormone with cardiac mortality risk in chronic hemodialysis patients

Hyperphosphatemia is highly prevalent among patients with end-stage renal disease (ESRD) and is associated with increased mortality risk in hemodialysis (HD) patients. The mechanism through which this mortality risk is mediated is unclear. Data from two national random samples of HD patients (n = 12,833) was used to test the hypothesis that elevated serum PO(4) contributes mainly to cardiac causes of death. During a 2-yr follow-up, the cause-specific relative risk (RR) of death for patients was analyzed separately for several categories of cause of death, including coronary artery disease (CAD), sudden death, and other cardiac causes, cerebrovascular and infection. Cox regression models were fit for each of the eight cause of death categories, adjusting for patient demographics and non-cardiovascular comorbid conditions. Time at risk for each cause-specific model was censored at death that resulted from any of the other causes. Higher mortality risk was seen for patients in the high PO(4) group (>6.5mg/dl) compared with the lower PO(4) group (< or =6.5mg/dl) for death resulting from CAD (RR 1.41; P < 0.0005), sudden death (RR 1.20; P < 0.01), infection (RR 1.20; P < 0.05), and unknown causes (RR 1.25; P < 0.05). Patients in the high PO(4) group also had non-significantly increased RR of death from other cardiac and cerebrovascular causes of death. The RR of sudden death was also strongly associated with elevated Ca x PO(4) product (RR 1.07 per 10 mg(2)/dl(2); P < 0.005) and serum parathyroid hormone levels greater than 495 pg/ml (RR 1.25; P < 0.05). This study identifies strong relationships between elevated serum PO(4), Ca x PO(4) product, and parathyroid hormone and cardiac causes of death in HD patients, especially deaths resulting from CAD and sudden death. More vigorous measures to reduce the prevalence of these factors in HD patients may result in improved survival.

Duration of dialysis and its relationship to dialysis adequacy, anemia management, and serum albumin level

An analysis of the relationship between intermediate outcomes and duration of dialysis therapy in hemodialysis patients was performed by linking Health Care Financing Administration (HCFA) Core Indicators data with data obtained from HCFA form 2728 at the initiation of dialysis therapy. Patients who recently initiated hemodialysis therapy were less likely to meet Dialysis Outcomes Quality Initiative guidelines than patients with a longer duration of dialysis therapy. For both urea reduction ratio and Kt/V, odds ratios for adequate dialysis were approximately 0.20 for a duration of dialysis therapy less than 0.5 years and 0.42 to 0.63 for a duration of dialysis therapy of 0.5 to 1.0 years compared with a duration of dialysis therapy of 2.0 years or greater. For patients with a duration of dialysis therapy less than 0.5 years (compared with >/=2.0 years), the odds ratio for a hematocrit less than 28% was approximately 3.0, that for a hematocrit 33% or greater was approximately 0.6, and that for a serum albumin level of 3.5 g/dL or greater (bromcresol green method) or 3.2 g/dL or greater (bromcresol purple method) was approximately 0.4. There was a direct relationship between glomerular filtration rate at the initiation of dialysis therapy and both serum albumin and hematocrit values. Patients administered recombinant human erythropoietin (rHuEPO) predialysis were more likely to have greater hematocrits. There also was a direct relationship between hematocrit and serum albumin level. Therefore, several actionable items in regard to attentive overall medical care can result in an improvement in the percentage of patients newly started on hemodialysis therapy who meet intermediate outcomes, including the administration of rHuEPO predialysis, correction of iron deficiency, and timely placement of a permanent dialysis access.

Assessment of the length of each hemodialysis session by on-line dialysate urea monitoring

Hemodialysis (HD) prescription is usually based on the periodical measurement of the Kt/V achieved in a midweek dialysis session. The purpose of the study was to assess the duration of each HD session to achieve a target dose of dialysis. This allowed to determine whether a given dialysis session may be considered representative of the other HD sessions. Seventy-two HD sessions were studied in 4 stable patients, who were randomly dialyzed during 3 consecutive periods, each lasting 2 weeks, using a different blood flow rate (Qb) in each period: 400, 300 or 200 ml/min. All HD were prolonged to achieve an on-line dialysate urea monitor (UM) Kt/V of 1.2. The UM Kt/V was compared with the Kt/V calculated using pre-HD, post-HD and rebound (45 min post-HD) plasma water urea concentrations. Comparison of the duration of the second midweek dialysis session with the length of the other HD showed 95% concordance intervals (+/-2 SD) of +/-21.08 min for Qb 400, +/-26.88 min for Qb 300 and +/-37.02 min for Qb 200 ml/min. The 95% concordance intervals for whole body urea clearance were +/-32.0, +/-20.36 and +/-15.62 ml/min for Qb 400, 300 and 200 ml/min, respectively. No differences were observed between UM Kt/V and blood-based double-pool Kt/V obtained by the second-generation Daugirdas (1.18 +/- 0.08) and Garred (1.19 +/- 0.08) Kt/V formulas. In conclusion, a great variability was observed between different HD sessions with regard to the whole body urea clearance and the time required to attain a target Kt/V even when the HD characteristics remained constant. The length of every HD required to achieve a target dose of dialysis can be assessed by on-line dialysate urea monitoring.

Effects of ultrapure dialysis fluid on nutritional status and inflammatory parameters

BACKGROUND

Malnutrition and chronic systemic inflammatory response syndrome not only coexist in uraemia, but may also have a bi-directional cause-and-effect relationship. To evaluate the role of dialysate-related cytokine induction in inflammatory response and nutritional status, we conducted a prospective comparison of two dialysis fluids differing in their microbiological quality.

METHODS

Forty-eight early haemodialysis patients were assigned to either treatment with conventional (potentially microbiologically contaminated) or on-line produced ultrapure dialysis fluid. Study parameters were bacterial growth, markers of systemic inflammation (C-reactive protein (CRP) and interleukin 6), and parameters of nutritional status (estimated dry weight, upper mid-arm muscle circumference, serum albumin concentration, insulin-like growth factor 1, leptin, and protein catabolic rate). Patients were followed for 12 months.

RESULTS

There were no statistically significant differences in demographic and treatment characteristics, degree of bacterial contamination of the dialysate, markers of systemic inflammation, or parameters of nutritional status among the two treatment groups at recruitment. Changing from conventional to ultrapure dialysis fluid reduced significantly the levels of IL-6 (19+/-3 pg/ml to 13+/-3 pg/ml) and CRP (1.0+/- 0.4 mg/dl to 0.5+/-0.2 mg/dl), and resulted in significant increases in estimated dry body weight, mid-arm muscle circumference, serum albumin concentration, levels of the humoral factors, and in protein catabolic rate after 12 months. Continuous use of conventional dialysis fluid (median 40-60 c.f.u./ml) was not associated with significant alterations in markers of inflammation (IL-6 21+/-4 pg/ml vs 24+/-6 pg/ml, CRP 0.9+/-0.3 mg/dl vs 1.1+/-0.4 mg/dl) or of nutritional status at any time of the study. All differences in systemic inflammation and nutritional parameters observed during the study period (from recruitment to month 12) were significant between the two patient groups.

CONCLUSIONS

Cytokine induction by microbiologically contaminated dialysis fluid has a negative impact on nutritional parameters of early haemodialysis patients. The microbiological quality of the dialysis fluid represents an independent determinant of the nutritional status in addition to known factors, such as dose of dialysis and biocompatibility of the dialyser membrane. Ultrapure dialysis fluid adds to the cost of the dialytic treatment, but may improve the nutritional status in long-term haemodialysis patients.

Family history of end-stage renal disease does not predict dialytic survival

Familial aggregation of end-stage renal disease (ESRD) is frequently observed in the common causes of kidney failure. It is unknown whether the clinical course of nephropathy differs based on an individual's family history of ESRD. The ESRD Network 6 Family History of ESRD database was analyzed to compare dialytic survival among patients with first- or second-degree relatives on dialysis therapy (positive family history) with those lacking relatives with ESRD (negative family history). Study participants included 3,442 adult, black or white, incident patients with ESRD who initiated dialysis therapy in ESRD Network 6 facilities in 1995 and participated in the Network-sponsored Family History of ESRD study. All deaths were reported to the Network and used to calculate mortality rates. The relative risk for death was used to compare rates between levels of patient characteristics. Multivariate analyses used proportional hazards regression. Overall, 730 patients (21.2%) had a positive family history of ESRD. Black patients, those who were younger at the onset of ESRD, patients with greater degrees of functional status, and women were more likely to have a positive family history. During 9,000 patient-years of follow-up, 1,599 patients died (17.8 deaths/100 dialysis-years). Univariate analyses showed that patients with a positive family history of ESRD had 20% lower mortality than those with a negative family history of ESRD (relative risk, 0.80; 95% confidence interval, 0.7 to 0.9; P = 0.001). Older age, white race, diabetic nephropathy, lower functional status, lower serum albumin level, congestive heart failure, and ischemic heart disease also were associated with greater mortality rates. Multivariate analyses showed that only older age at onset of ESRD, white race, low functional status, ESRD caused by diabetes, and congestive heart failure were associated with increased mortality. A family history of ESRD in either first- or second-degree relatives was no longer a significant determinant of survival. We conclude that familial clustering of ESRD does not significantly impact on dialytic survival after controlling for the competing effects of patient race, age of ESRD onset, and the presence of diabetes mellitus.

Conversion between bromcresol green- and bromcresol purple-measured albumin in renal disease

BACKGROUND

Albumin measured by a bromcresol purple dye-binding assay (Alb(BCP)) agrees more closely with the gold standard of immunonephelometry than does bromcresol green (Alb(BCG)) measurement. Both tests are in current clinical use. A method for converting between the two would be useful.

METHODS

We measured albumin by bromcresol green and bromcresol purple in 535 patients, 155 of whom had renal disease. We randomly divided data from the patients with renal disease into two equal-sized sets, and used one set to derive, and the remaining set to validate, a regression equation relating the two values.

RESULTS

The relationship Alb(BCG)=5.5+Alb(BCP) performed very well in both the renal patient validation set and in the data from 380 unselected in-patients and out-patients. Intraclass correlations for agreement between measured Alb(BCG) and predicted Alb(BCG) was 0.98 in both analyses.

CONCLUSIONS

The ability to convert between these measurements will be of use in clinical situations where the absolute value of the serum albumin is important, when data from laboratories using different methodologies must be combined, and in the application of the Modification of Diet in Renal Disease formula to estimate glomerular filtration rate in patients whose albumin has been measured by bromcresol purple.

Hyperhomocysteinemia in chronic renal failure patients: relation to nutritional status and cardiovascular disease

A moderate increase in plasma total homocysteine (tHcy) is considered to be an independent risk factor for cardiovascular disease (CVD) in the general population. Almost all chronic renal failure (CRF) patients have plasma concentration of tHcy that is elevated 3 to 4 times above normal. The prevalence of CVD, diabetes mellitus, malnutrition and hypoalbuminemia is high in CRF patients. Previous investigations have focused on the role of vitamin status on plasma tHcy in CRF patients, but little information exists on the influence of nutritional status and hypoalbuminemia on plasma tHcy in CRF, although a substantial fraction of tHcy (>70%) is protein-bound, mainly to albumin. Our study in patients with end-stage renal disease showed that more than 90% of the patients had elevated plasma tHcy levels, which were higher in patients with normal nutritional status than in malnourished patients. Moreover, plasma tHcy was inversely correlated with subjective global nutritional assessment (high values denote malnutrition) and positively correlated with serum albumin and protein intake. Hence, it seems likely that serum-albumin is a strong determinant of plasma tHcy in CRF patients and this may contribute to the lower tHcy levels in malnourished patients. Patients with diabetes mellitus had lower serum-albumin and plasma tHcy than non-diabetic patients, irrespective whether they were malnourished or not. Patients with CVD had lower (although still elevated) plasma tHcy levels than those without CVD. An explanation may be that the prevalence of diabetes mellitus, malnutrition and hypoalbuminema, i.e. factors that decrease tHcy, was higher in patients with CVD, which may explain why they had less elevated values. Assuming that hyperhomocysteinemia carries an independent risk of CVD, this implies that almost all CRF patients are exposed to this risk. CRF patients with CVD had a higher prevalence of malnutrition, hypoalbuminemia and diabetes mellitus, which was associated with a lower plasma Hcy level. This may explain why plasma tHcy was lower (although still abnormally high) in patients with CVD than in patients without CVD. The lower tHcy levels in CVD patients do not contradict the assumption that hyperhomocysteinemia is a risk factor for CVD since almost all patients are exposed to this risk, and other factors might be present that confound the relationship between the absolute tHcy levels and CVD. Our findings imply that nutritional status and serum albumin, as well as the presence of diabetes mellitus, should be taken into consideration when evaluating tHcy as a risk factor for CVD in CRF patients.

Residual renal function and mortality risk in hemodialysis patients

Residual renal function, defined as the urinary clearance of urea and creatinine, is minimal in many patients treated with hemodialysis (HD) and tends to be ignored in most outcome studies involving HD patients. Recent studies showed that residual renal function, even at a low level, is influential in preventing mortality in the minority of patients with end-stage renal disease treated with peritoneal dialysis. This issue generally has not been examined in patients treated with HD. This prospective observational study of all 114 patients at a single community-based freestanding HD center is designed to examine the impact of residual renal function (defined as renal urea clearance and renal creatinine clearance derived from 24-hour urinary volumes) on mortality over a 2-year period. During that period, 50 deaths occurred in 114 patients. The presence of residual renal function was protective against mortality (odds ratio for death, 0.44; 95% confidence interval, 0.24 to 0.81; P = 0.008), even after adjustment for duration of dialysis treatment, age, smoking, presence of diabetes, presence of cardiovascular disease, serum albumin level, and urea reduction rate. In conclusion, the presence of residual renal function, even at a low level, is associated with a lower mortality risk in HD patients.

Renal function and renal disease in the elderly: Part II

In all industrialized countries, life expectancy has risen in the past 100 years. The incidence of elderly patients reaching end-stage renal disease (ESRD) and requiring renal replacement therapy has also increased. During the past few decades, the pattern of ESRD has changed significantly with the emerging predominance of elderly patients. The causes of this phenomenon are manifold and include an increasing number of chronic diseases typical of the 'third age', such as type 2 diabetes mellitus and vascular disease. In many species, a consequence of aging includes deterioration of renal function, partly due to structural alterations, and partly as the result of a diminishing blood flow. In humans, the aging kidney is characterized by modifications resulting from organic and functional disturbances. In particular, type 2 diabetes mellitus has emerged as an important condition, the microvascular and macrovascular complications of which are a common cause of morbidity and mortality in older patients. In Part II of this review, the specific aspects of renal replacement therapy in the elderly will be discussed.

NUTRITIONALMANAGEMENT OFMAINTENANCEDIALYSISPATIENTS: Why Aren't We Doing Better?

About 40% of patients undergoing maintenance dialysis suffer from varying degrees of protein-energy malnutrition. This is a problem of substantial importance because many measures of nutritional status correlate with the risk of morbidity and mortality. There are many causes of protein-energy malnutrition in maintenance dialysis patients. Evidence indicates that nutritional decline begins even when the reduction in glomerular filtration rate is modest, and it is likely that the observed decrease in dietary protein and energy intake plays an important role. The nutrient intake of patients receiving maintenance dialysis also is often inadequate, and several lines of evidence suggest that toxins that accumulate with renal failure suppress appetite and contribute to nutritional decline once patients are on maintenance dialysis. Recent epidemiologic studies have suggested that both increased serum levels of leptin and inflammation may reduce nutrient intake and contribute to the development of protein-energy malnutrition. It is likely that associated illnesses, which are highly prevalent, contribute to malnutrition in maintenance dialysis patients. Recent data from the United States Renal Data System registry suggest that in the United States, the mortality rate of dialysis patients is improving. However, it remains high. We offer suggestions for predialysis and dialysis care of these patients that can result in improvement in their nutritional status. Whether this improvement will result in a decrease in patient morbidity and mortality is unknown.

Explaining counter-intuitive clinical outcomes predicted by Kt/V

Population-based studies of maintenance hemodialysis patients have demonstrated a reproducible relationship between the dose of hemodialysis and mortality and morbidity outcomes. In these analyses, which have aggregated hemodialysis patient subgroups, improved outcomes are associated with greater doses of hemodialysis. However, remarkable counterintuitive findings are observed if patients are analyzed by subgroups based on their race, gender, and anthropometric and blood-based biomarkers of nutritional state. For example, blacks generally receive lower doses of hemodialysis than whites, but enjoy relatively improved survival; patients who receive the highest doses of hemodialysis have an increased death risk; and the dose response curve between hemodialysis and survival is altered based on the patients' body mass index. These seemingly paradoxical relationships between hemodialysis dose and patient survival can be explained because of the use of mathematical urea kinetic constructs as clinical outcome predictors; they integrate a measure of solute removal (K x t) with an anthropometric surrogate of nutrition, the urea distribution volume (V). Both these measures have an independent influence on patient survival and in some clinical circumstances are of unequal power as clinical outcome predictors. These complex interactions must be kept in perspective as clinical care is delivered in the context of hemodialysis dose.

Serial prealbumin levels as predictors of outcomes in a retrospective cohort of peritoneal and hemodialysis patients

OBJECTIVE

Although earlier research has suggested that baseline prealbumin level is an independent predictor of outcome among dialysis patients, the prognostic importance of serial prealbumin levels is less clear. The present study had 3 objectives: first, to determine if prealbumin (a marker of visceral protein stores with a relatively short half-life) predicts subsequent albumin levels taken at least 1 month later; second, to examine the association between serial prealbumin levels and clinical outcome; and third, to examine the association between changes in prealbumin level and outcome.

DESIGN

The prognostic value of serial prealbumin levels was examined by linear regression analysis and Cox hazard models in an observational cohort study using a repeated measures design and time-dependent covariates.

SETTING

Patients were followed by a tertiary care center, receiving hemodialysis (HD; at either an in-center dialysis unit or one of several satellite units operated by the hospital) or home peritoneal dialysis (PD).

PATIENTS

A retrospective cohort was identified consisting of 268 incident and prevalent chronic HD and PD patients receiving dialysis from June 1998 to September 1999.

MAIN OUTCOME

The study examined the association between serial prealbumin measurements and future laboratory and clinical outcomes (albumin, hospitalization, and death).

RESULTS

Serial prealbumin values were independent predictors of future albumin levels among HD patients (P =.04), but not PD patients. Independent predictors of hospitalization included diabetes for PD patients (P =.0012) and advanced age for HD patients (P =.0008). Advanced age and diabetes were independent predictors of death for both HD (P =.0001 and P =.0368) and PD patients (P =.0014 and P =.0164). Serial prealbumin values, measured as time-dependent covariates, did not predict hospitalization or death. Further analyses examined the prognostic value of changes in prealbumin and albumin values as time-dependent covariates. The final multivariate analysis identified low baseline albumin level as an independent predictor of hospitalization among HD patients (P =.0282), whereas low baseline prealbumin was an independent predictor of death for HD patients (P =.0001). Interestingly, negative changes in serial prealbumin measurements were also independent predictors of death among HD patients (P =.0025).

CONCLUSION

Serial prealbumin measurements predict subsequent albumin values among HD patients. As well, low baseline prealbumin level is an independent predictor of adverse outcome among HD patients. Although repeated prealbumin measurements in and of themselves were of no added prognostic value, falling prealbumin values identified by repeated measurements were additional independent predictors of death. These results support the clinical utility of regular prealbumin monitoring among HD patients.

Comparison of the effects of two early intervention strategies on the health outcomes of malnourished hemodialysis patients

OBJECTIVE

To determine the efficacy and cost-effectiveness of providing oral supplementation early in the course of malnutrition for hemodialysis (HD) patients.

DESIGN

The study design consisted of 3 groups: an experimental group, a control group of patients with mild hypoalbuminemia (HA) (serum albumin [SA] = 3.5 to 3.7 g/dL), and a comparison group of patients with moderate to severe HA (SA = 2.5 to 3.4 g/dL).

SETTING

Ten outpatient hemodialysis centers in southeast lower Michigan.

PATIENTS

Treatment and control groups consisted of 32 HD patients with mild HA. Fourteen HD patients with moderate to severe HA comprised the comparison group.

INTERVENTION

The experimental group received diet counseling and oral supplementation, and the control group received diet counseling only. The comparison group received physician-prescribed oral supplements and dietary counseling to permit comparison of the experimental treatment with current supplementation practices.

MAIN OUTCOME MEASURES

Differences between groups in the number of patients reaching nutritional repletion, change in SA levels at the end of the study, and follow-up periods, were tested using chi-square analysis. Analysis of variance was used to compare group differences in treatment duration to repletion and number of hospitalization days.

RESULTS

During the study period, significantly more patients reached nutritional repletion in the experimental group and control group (50% and 57%, respectively) than in the comparison group (7%). Overall, repletion occurred more quickly in the experimental group (3.2 +/- 1.7 months) than in the control group (3.5 +/- 1.2 months), with a larger number of patients in the experimental group repleted by month 2 of the study phase. During follow-up, patients in the experimental group were far more likely to maintain nutritional repletion or continue to improve (61%) than patients in the control group (14%). Although too few patients were hospitalized to show statistical significance, there was a trend toward greater numbers of hospital days in more malnourished patients (208 days for the comparison group), followed by those with mild HA who did not receive oral supplements (107 days), and the experimental group (71 days).

CONCLUSION

Although the sample size for this study was too small for the results to be conclusive, it appears that use of nutritional supplements early in the course of malnutrition may provide benefits such as, attaining nutritional repletion more quickly, which results in less product usage. It is also more likely that good nutritional status will be maintained after supplementation is discontinued.

Using artificial intelligence to predict the equilibrated postdialysis blood urea concentration

Total dialysis dose (Kt/V) is considered to be a major determinant of morbidity and mortality in hemodialyzed patients. The continuous growth of the blood urea concentration over the 30- to 60-min period following dialysis, a phenomenon known as urea rebound, is a critical factor in determining the true dose of hemodialysis. The misestimation of the equilibrated (true) postdialysis blood urea or equilibrated Kt/V results in an inadequate hemodialysis prescription, with predictably poor clinical outcomes for the patients. The estimation of the equilibrated postdialysis blood urea (eqU) is therefore crucial in order to estimate the equilibrated (true) Kt/V. In this work we propose a supervised neural network to predict the eqU at 60 min after the end of hemodialysis. The use of this model is new in this field and is shown to be better than the currently accepted methods (Smye for eqU and Daugirdas for eqKt/V). With this approach we achieve a mean difference error of 0.22 +/- 7.71 mg/ml (mean % error: 1.88 +/- 13.46) on the eqU prediction and a mean difference error for eqKt/V of -0.01 +/- 0.15 (mean % error: -0.95 +/- 14.73). The equilibrated Kt/V estimated with the eqU calculated using the Smye formula is not appropriate because it showed a great dispersion. The Daugirdas double-pool Kt/V estimation formula appeared to be accurate and in agreement with the results of the HEMO study.

Children with hypoalbuminemia on continuous peritoneal dialysis are at risk for technique failure

BACKGROUND

Few data are available on the clinical significance of hypoalbuminemia [serum albumin (SA) <35 g/L] in children with end-stage renal disease (ESRD) on continuous peritoneal dialysis (CPD). This study was conducted to analyze the prevalence of hypoalbuminemia, its predictive factors, and its clinical impact in these children.

METHODS

A retrospective analysis was done of 180 patients on CPD over the last 22 years. Patients were excluded from the study if they were on CPD for less than four months or had nephrotic syndrome. Demographic, clinical, and biochemical variables were studied. Children continued on CPD until they received a transplant or were transferred to an adult unit or to hemodialysis as a result of technique failure. The subjects were divided into two groups based on SA levels at last follow-up.

RESULTS

A total of 135 children was included. After a mean duration of CPD of 573 +/- 437 (120 to 2960) days, 54 children (40%) were observed to have hypoalbuminemia. Four patients (2.9%) died, 7 (5.2%) continued on continuous cyclic peritoneal dialysis, and 13 (9.6%) were transferred to an adult unit for continuation of CPD. Ninety-five (70.3%) were transplanted, and 16 (11.8%) were transferred to hemodialysis because of technique failure. Children in group I (N = 54, SA <35 g/L), compared with group II (N = 81, SA > or =35 g/L), were younger at initiation of PD, more likely to have hypoalbuminemia at one month and six months after initiation of PD, and have more episodes of peritonitis. No differences were seen between the groups in gender, modality of CPD, body surface area, initial body mass index, and presence of hypertension or acidosis. The only factors predictive of hypoalbuminemia on follow-up were low SA at one month after PD and recurrent peritonitis using multiple logistic regression analysis. Evaluating the clinical impact of hypoalbuminemia, we observed a higher incidence of failed PD in children who had hypoalbuminemia.

CONCLUSION

Low SA at one month after PD and recurrent peritonitis are predictive of hypoalbuminemia in children on CPD, which is associated with an increased incidence of CPD failure.