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

Nutritional status in hemodialysis patients and bioimpedance vector analysis

The goal of our study was to evaluate the nutritional status of a hemodialysis population through bioimpedance vector analysis (BIVA) and compare the obtained results with conventional clinical laboratory indexes, the validity of which are still a subject of controversy. Eighty adult white hemodialysis patients were enrolled in the study. Their nutritional status was estimated through their body mass index, the percentage deviation of the real body weight to ideal body weight (DeltaP%), Kt/V, normalized protein catabolic rate (nPCR), serum albumin, and BIVA. The incidence of malnutrition was different according to the parameter considered. The logistic regression analysis between the BIVA score and the other nutritional parameters showed that albumin and nPCR can be considered as independent factors able to influence BIVA, with statistical significance. This affects patients with normal values of other nutritional indexes, but fades out when considering patients with low nutritional values. Therefore, nPCR and albumin influence the BIVA determination of the examined population, but this influence affects patients with normal nutritional indexes and disappears when we consider undernourished patients. In conclusion, our results show that hypoalbuminemia, inadequate protein intake, a low Kt/V, a high DeltaP%, or a low body mass index cannot be considered as reliable markers for malnutrition.

Is a single time point C-reactive protein predictive of outcome in peritoneal dialysis patients?

C-reactive protein is the prototype marker of inflammation and has been shown to predict mortality in hemodialysis patients. However, it remains uncertain as to whether a single C-reactive protein level has similar prognostic significance in peritoneal dialysis patients. A single high-sensitivity C-reactive protein (hs-CRP) level was measured in 246 continuous ambulatory peritoneal dialysis patients without active infections at study baseline together with indices of dialysis adequacy, echocardiographic parameters (left ventricular mass index, left ventricular dimensions, and ejection fraction), nutrition markers (serum albumin, dietary intake, and subjective global assessment) and biochemical parameters (hemoglobin, lipids, calcium, and phosphate). The cohort was then followed-up prospectively for a median of 24 mo (range, 2 to 34 mo), and outcomes were studied in relation to these parameters. Fifty-nine patients died (36 from cardiovascular causes) during the follow-up period. The median hs-CRP level was 2.84 mg/L (range, 0.20 to 94.24 mg/L). Patients were stratified into tertiles according to baseline hs-CRP, namely those with hs-CRP < or = 1.26 mg/L, 1.27 to 5.54 mg/L, and > or = 5.55 mg/L. Those with higher hs-CRP were significantly older (P < 0.001), had greater body mass index (P < 0.001), higher prevalence of coronary artery disease (P = 0.003), and greater left ventricular mass index (P < 0.001). One-year overall mortality was 3.9% (lower) versus 8.8% (middle) versus 21.3% (upper tertile) (P < 0.0001). Cardiovascular death rate was 2.7% (lower) versus 5.2% (middle) versus 16.2% (upper tertile) (P < 0.0001). Multivariable Cox regression analysis showed that every 1 mg/L increase in hs-CRP was independently predictive of higher all-cause mortality (hazard ratio [HR], 1.02; 95% CI, 1.01 to 1.04; P = 0.002) and cardiovascular mortality (HR, 1.03; 95% CI, 1.01 to 1.05; P = 0.001) in peritoneal dialysis patients. Other significant predictors for all-cause mortality included age (HR, 1.07; 95% CI, 1.04 to 1.10), gender (HR, 0.49; 95% CI, 0.27 to 0.90), atherosclerotic vascular disease (HR, 2.65; 95% CI, 1.46 to 4.80), left ventricular mass index (HR, 1.01; 95% CI, 1.00 to 1.01) and residual GFR (HR, 0.53; 95% CI, 0.38 to 0.75). Age (HR, 1.06; 95% CI, 1.02 to 1.10), history of heart failure (HR, 3.31; 95% CI, 1.36 to 8.08), atherosclerotic vascular disease (HR, 3.20; 95% CI, 1.43 to 7.13), and residual GFR (HR, 0.57; 95% CI, 0.38 to 0.86) were also independently predictive of cardiovascular mortality. In conclusion, a single, random hs-CRP level has significant and independent prognostic value in PD patients.

Health-related quality of life as a predictor of mortality and hospitalization: the Dialysis Outcomes and Practice Patterns Study (DOPPS)

BACKGROUND

We investigated whether indicators of health-related quality of life (HRQOL) may predict the risk of death and hospitalization among hemodialysis patients treated in seven countries, taking into account serum albumin concentration and several other risk factors for death and hospitalization. We also compared HRQOL measures with serum albumin regarding their power to predict outcomes.

METHODS

We analyzed data from the Dialysis Outcomes and Practice Patterns Study (DOPPS), an international, prospective, observational study of randomly selected hemodialysis patients in the United States (148 facilities), five European countries (101 facilities), and Japan (65 facilities). The total sample size was composed of 17,236 patients. Using the Kidney Disease Quality of Life Short Form (KDQOL-SFTM), we determined scores for three components of HRQOL: (1) physical component summary (PCS), (2) mental component summary (MCS), and (3) kidney disease component summary (KDCS). Complete responses on HRQOL measures were obtained from 10,030 patients. Cox models were used to assess associations between HRQOL and the risk of death and hospitalization, adjusted for multiple sociodemographic variables, comorbidities, and laboratory factors.

RESULTS

For patients in the lowest quintile of PCS, the adjusted risk (RR) of death was 93% higher (RR = 1.93, P < 0.001) and the risk of hospitalization was 56% higher (RR = 1.56, P < 0.001) than it was for patients in the highest quintile level. The adjusted relative risk values of mortality per 10-point lower HRQOL score were 1.13 for MCS, 1.25 for PCS, and 1.11 for KDCS. The corresponding adjusted values for RR for first hospitalization were 1.06 for MCS, 1.15 for PCS, and 1.07 for KDCS. Each RR differed significantly from 1 (P < 0.001). For 1 g/dL lower serum albumin concentration, the RR of death adjusted for PCS, MCS, and KDCS and the other covariates was 1.17 (P < 0.01). Albumin was not significantly associated with hospitalization (RR = 1.03, P> 0.5).

CONCLUSION

Lower scores for the three major components of HRQOL were strongly associated with higher risk of death and hospitalization in hemodialysis patients, independent of a series of demographic and comorbid factors. A 10-point lower PCS score was associated with higher elevation in the adjusted mortality risk, as was a 1 g/dL lower serum albumin level. More research is needed to assess whether interventions to improve quality of life lower these risks among hemodialysis patients.

Initial body mass indexes have contrary effects on change in body weight and mortality of patients on maintenance hemodialysis treatment

Malnutrition is a relevant risk factor for mortality for patients on maintenance hemodialysis treatment. In a retrospective study including 377 patients who began hemodialysis treatment between 1986 and 2001, we assessed the prevalence of different statuses of nutrition and the impact of the initial status of nutrition on the change in body weight and patient survival. We found an inverse relationship between body mass index (BMI, kg/m2) and the gain in body weight and BMI within 12 months of hemodialysis treatment. Underweight and normal weight patients had a substantial increase in these parameters, greatest in underweight subjects, whereas overweight and obese patients showed only a moderate increase or none (P =.0019, P =.00036). Adjusted mortality rates showed an inverse correlation with the initial BMI (P <.0001). There was a statistically significant difference in the mortality between patients with normal weight and overweight or obesity, respectively, showing a more favorable prognosis in overweight and obese patients (P =.0007; P =.022; log-rank, normal versus overweight, P =.012). Weight loss was the greatest independent risk factor for mortality in general. Adjusted hazard ratio of death was highest in underweight patients (3.999; CI, 2.708 to 5.905; P <.0001) and decreased to 2.251 (CI, 1.795 to 2.822; P <.0001) in normal weight, 1.927 (CI, 1.390 to 2.670; P <.0001) in overweight, and 1.651 (CI, 0.841 to 3.236; P =.1439) in obese subjects when patients with weight loss were compared with patients who preserved their initial weight or gained weight. Overall, the initial BMI has an influence on the change in body weight as well as on patient survival in general and in the case of weight loss in particular.

Dialysate-side urea kinetics. Neural network predicts dialysis dose during dialysis

Determination of the adequacy of dialysis is a routine but crucial procedure in patient evaluation. The total dialysis dose, expressed as Kt/V, has been widely recognised to be a major determinant of morbidity and mortality in haemodialysed patients. Many different factors influence the correct determination of Kt/V, such as urea sequestration in different body compartments, access and cardiopulmonary recirculation. These factors are responsible for urea rebound after the end of the haemodialysis session, causing poor Kt/V estimation. There are many techniques that try to overcome this problem. Some of them use analysis of blood-side urea samples, and, in recent years, on-line urea monitors have become available to calculate haemodialysis dose from dialysate-side urea kinetics. All these methods require waiting until the end of the session to calculate the Kt/V dose. In this work, a neural network (NN) method is presented for early prediction of the Kt/V dose. Two different portions of the dialysate urea concentration-time profile (provided by an on-line urea monitor) were analysed: the entire curve A and the first half B, using an NN to predict the Kt/V and compare this with that provided by the monitor. The NN was able to predict Kt/V is the middle of the 4h session (B data) without a significant increase in the percentage error (B data: 6.69% +/- 2.46%; A data: 5.58% +/- 8.77%, mean +/- SD) compared with the monitor Kt/V.

Effects of growth hormone in patients with chronic renal failure: experience in children and adults

Recombinant human growth hormone (GH) has proven effective in promoting growth in short children with chronic renal failure before and after renal transplantation. The action of GH and its mediator insulin-like growth factor 1 on body composition, protein, glucose and bone metabolism offers additional therapeutic options. One might be the improvement of the catabolic state in adults with end-stage renal failure. In few pilot studies and two placebo-controlled studies of 6 months duration, GH treatment in adults on dialysis showed clear anabolic effects resulting in a significant increase in lean body mass.

Ankle-brachial blood pressure index predicts all-cause and cardiovascular mortality in hemodialysis patients

A reduction in ankle-brachial BP index (ABPI) is associated with generalized atherosclerotic diseases and predicts cardiovascular mortality and morbidity in several patient populations. However, a large-scale analysis of ABPI is lacking for hemodialysis (HD) patients, and its use in this population is not fully validated. A cohort of 1010 Japanese patients undergoing chronic hemodialysis was studied between November 1999 and May 2002. Mean age at entry was 60.6 +/- 12.5 yr, and duration of follow-up was 22.3 +/- 5.6 mo. Patients were stratified into five groups (< 0.9, > or = 0.9 to < 1.0, > or = 1.0 to < 1.1, > or = 1.1 to < 1.3, and > or = 1.3) by ABPI measured at entry by an oscillometric method. The frequency distribution of ABPI was 16.5% of patients < 0.9, 8.6% of patients > or = 0.9 to < 1.0, 16.9% of patients 1.0 > or = to < 1.1, and 47.0% of patients > or 1.1 to < 1.3, whereas 10.9% of patients had an abnormally high ABPI (> or = 1.3). The relative risk of a history of diabetes mellitus (DM), cardiovascular, and cerebrovascular disease was significantly higher in patients with lower ABPI than those with ABPI > or = 1.1 to <1.3. During the study period, 77 cardiovascular and 41 noncardiovascular fatal events occurred. On the basis of Cox proportional hazards regression analysis, ABPI emerged as a strong independent predictor of all-cause and cardiovascular mortality. After adjustment for confounding variables, the hazard ratio (HR) for ABPI < 0.9 was 4.04 (95% confidence interval, 2.38 to 6.95) for all-cause mortality and 5.90 (2.83 to 12.29) for cardiovascular mortality. Even those with modest reductions in the ABPI (> or = 0.9 to <1.1) appeared to be at increased risk. Patients having abnormally high ABPI (> or = 1.3) also had poor prognosis (HR, 2.33 [1.11 to 4.89] and 3.04 [1.14 to 8.12] for all-cause and cardiovascular mortality, respectively). Thus, the present findings validate ABPI as a powerful and independent predictor for all-cause and cardiovascular mortality among hemodialysis patients.

One-year growth hormone therapy improves granulocyte function without major effects on nutritional and anthropometric parameters in malnourished hemodialysis patients

BACKGROUND/AIMS

Growth hormone (GH) resistance leads to enhanced protein catabolism and contributes to the malnutrition of patients with chronic renal failure (CRF). In short-term trials anabolic effects of rhGH therapy have been demonstrated in patients on chronic hemodialysis.

METHODS

This study was initiated to determine the effects of 12 months of rhGH therapy on polymorphonuclear leukocyte (PMNL) function as well as on nutritional and anthropometric parameters. 0.125 IU/kg rhGH was given 3 times a week during the first 4 weeks and 0.25 IU/kg thereafter to 19 malnourished hemodialysis patients with a mean age of 59.3 +/- 13.4 years.

RESULTS

Insulin-like growth factor I (IGF-I) concentrations rose significantly from 169.2 +/- 95.6 to 262.9 +/- 144.4 ng/ml (p < 0.01) in the first 3 months, but declined thereafter. Phagocytic activity of PMNLs also increased significantly in response to rhGH therapy and this activation remained stable over the whole 12-month period. Other parameters of PMNL function were not influenced by rhGH therapy. In addition, nutritional parameters such as albumin, prealbumin, transferrin, cholesterol, HDL-cholesterol, cholinesterase, predialytic creatinine and blood urea nitrogen were not affected by rhGH therapy. A decline of total body fat (TBF) was observed after 3 and 9 months of rhGH therapy (17.5 +/- 10 vs. 16.7 +/- 10% after 3 months, p < 0.017 and 16.8 +/- 8.7% after 9 months, p < 0.049), whereas lean body mass remained stable.

CONCLUSIONS

Twelve months of rhGH therapy caused a significant increase in IGF-I levels, stimulated phagocytic activity of PMNLs and induced a decline of TBF. Other anthropometric and nutritional parameters were not affected, which might be related to the persistence of GH resistance.

Determinants of survival among HIV-infected chronic dialysis patients

Over 100 HIV-infected patients have initiated chronic dialysis at San Francisco General Hospital (SFGH) since 1985. This study employed retrospective analysis to identify determinants of and trends in survival among HIV-infected patients who have initiated chronic dialysis at SFGH from January 1, 1985 to November 1, 2002 (n = 115). Cohort patient survival was compared with survival after an AIDS-opportunistic illness in all HIV-infected patients in San Francisco during the study period. Higher CD4 count (hazard ratio [HR], 0.86 per 50 cells/mm(3) increase; 95% confidence interval [CI], 0.80 to 0.93) and serum albumin (HR, 0.53 per 1 g/dl increase; CI, 0.36 to 0.78) at initiation of dialysis were strongly associated with lower mortality. Survival for those initiating dialysis during the era of highly active antiretroviral therapy (HAART) was 16.1 mo versus 9.4 mo for those initiating dialysis before this time, but this difference was not statistically significant. In adjusted analysis, only a non-statistically significant trend toward improved survival during the HAART era was noted (HR, 0.59; CI, 0.34 to 1.04). By comparison, survival for all HIV-infected patients after an AIDS-opportunistic illness in San Francisco increased from 16 mo in 1994 to 81 mo in 1996. The dramatic improvement in survival that has occurred since the mid-1990s for patients with HIV appears to be greatly attenuated in the sub-group undergoing dialysis. Although this may partly reflect confounding by race, injection drug use and HCV co-infection, future attempts to improve survival among HIV-infected dialysis patients should focus on barriers to the effective use of HAART in this group.

Association of depression with malnutrition in chronic hemodialysis patients

BACKGROUND

Depression is the most common psychological complication and may increase mortality in chronic hemodialysis patients. Because depression could be associated with poor oral intake and activation of proinflammatory cytokines that could further increase mortality by malnutrition, we investigated the relation between depression and nutritional status in chronic hemodialysis patients.

METHODS

Sixty-two Korean patients completed the Beck Depression Inventory (BDI) questionnaire, and the diagnosis of depression was confirmed by Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria for major depressive disorder. Nutritional status was evaluated using serum albumin level, normalized protein catabolic rate, subjective global assessment (SGA), and anthropometric measurement.

RESULTS

Mean BDI score was 22.7 +/- 11.4, and 35 patients (56.5%) had a BDI score greater than 21, which is the suggested cutoff score for the diagnosis of depression for the Korean population. Of 40 patients who had a score higher than 18 on the BDI, 34 patients met DSM-IV criteria for major depressive disorder. BDI score correlated negatively with a variety of nutritional parameters: serum albumin level (r = -0.47; P < 0.001), normalized protein catabolic rate (r = -0.32; P < 0.05), SGA (r = -0.47; P < 0.01), triceps skinfold thickness (r = -0.40; P < 0.05), midarm muscle circumference (r = -0.57; P < 0.01), and body mass index (r = -0.28; P < 0.05). Multiple regression analysis also identified BDI score as an independent determinant for all kinds of nutritional parameters.

CONCLUSION

In patients on chronic hemodialysis therapy, depression is related closely to nutritional status and could be an independent risk factor for malnutrition.

New insights in uremic toxins

The retention in the body of compounds, which normally are secreted into the urine results in a clinical picture, called the uremic syndrome. The retention compounds responsible for the uremic syndrome are called uremic toxins. Only a few of the uremic retention solutes fully conform to a true definition of uremic toxins. Uremic patients develop atheromatotic vascular disease more frequently and earlier than the general population. The classical risk factors seem to be less important. Other factors have been suggested to be at play, and among those uremic toxins are mentioned as potential culprits. The identification, classification and characterization of the solutes responsible for vascular problems seems of utmost importance but is far from complete due to a lack of standardization and organization. The European Uremic Toxin Work Group (EUTox) has as a primary aim to discuss, analyze and offer guidelines in matters related to the identification, characterization, analytical determination and evaluation of biological activity of uremic retention solutes. The final aim remains the development of new strategies to reduce the concentration of the most active uremic solutes. These activities will at first be concentrated on reducing factors influencing cardiovascular morbidity and mortality.

On-line monitoring of solutes in dialysate using wavelength-dependent absorption of ultraviolet radiation

The aim of the study was to assess the wavelength dependence of the UV absorbance during monitoring of different compounds in the dialysate. UV absorbance was determined by using a double-beam spectrophotometer on dialysate samples taken at pre-determined times during dialysis, over a wavelength range of 180-380 nm. Concentrations of several removed substances, such as urea, creatinine, uric acid, phosphate and beta2-microglobulin, were determined in the blood and in the spent dialysate samples using standard laboratory techniques. Millimolar extinction coefficients, for urea, creatinine, monosodium phosphate and uric acid were determined during laboratory bench experiments. The correlation between UV absorbance and substances both in the dialysate and in the blood was calculated at all wavelengths. A time-dependent UV absorbance was determined on the collected dialysate samples from a single dialysis session over a wavelength range of 200-330 nm. The highest contribution from observed compounds relative to the mean value of the absorbance was found around 300 nm and was approximately 70%. The main contribution to the total absorbance from uric acid was confirmed at this wavelength. The highest correlation for uric acid, creatinine and urea was obtained at wavelengths from 280 nm to 320 nm, both in the spent dialysate and in the blood. The wavelength region with the highest correlation for phosphate and beta2-microglobulin, with a suitable UV-absorbance dynamic range, was from 300 to 330 nm. In the wavelength range of 220-270 nm the highest absorbance sensitivity for the observed substances was obtained. A suitable wavelength range for instrumental design seems to be around 290-330 nm. The relatively high correlation between UV absorbance and the substances in the spent dialysate and in the blood indicates that the UV-absorbance technique can estimate the removal of several retained solutes known to accumulate in dialysis patients.

A comparison of dual dialyzers in parallel and series to improve urea clearance in large hemodialysis patients

BACKGROUND

Dialysis adequacy targets frequently are difficult to achieve in large hemodialysis patients. Dual dialyzers can be used to improve clearance. It is unknown whether series or parallel configurations are superior.

METHODS

Eighteen large hemodialysis patients (mean weight, 92.4 kg) were enrolled in a randomized, crossover trial to directly compare dual dialyzers in parallel and series configurations. Treatment times, blood flow rates, and dialysate flow rates were kept constant.

RESULTS

Compared with a single dialyzer, parallel dual dialyzers increased the single-pool Kt/V (spKt/V) from 1.25 +/- 0.22 to 1.43 +/- 0.29 (P < 0.003). Series dual dialyzers improved urea clearance measured by spKt/V (spKt/V(urea)) to 1.46 +/- 0.26 (P < 0.0003 compared with a single dialyzer). Kt/V and urea reduction ratio of dual dialyzers in parallel were not significantly different from those of dual dialyzers in series. Half the subjects failed to meet the National Kidney Foundation-Kidney Disease Outcomes Quality Initiative recommended adequacy target for spKt/V(urea) of 1.2 or less using a single dialyzer. With the use of dual dialyzers, 83% of subjects achieved this adequacy target. Serum levels of a middle molecule, beta2-microglobulin, were reduced 34% after 2 months of dual-dialyzer therapy. Cost analysis estimates annual net savings of 1,260 dollars with dual-dialyzer therapy, primarily from projected savings in inpatient expenses.

CONCLUSION

In large hemodialysis patients, our study shows that dual dialyzers in parallel and series are equally effective at improving urea clearance without prolonging dialysis treatment times.

Correlates of urea kinetic modeling during hemodialysis in patients with acute renal failure

The current guidelines on dialysis adequacy in acute renal failure (ARF) are loosely defined and have been extrapolated from patients with end-stage renal disease. The objectives of this study were (1) to compare three methods of urea kinetic modeling measurement in patients with ARF receiving intermittent hemodialysis, (2) to compare prescribed to delivered dose of dialysis, and (3) to explore the factors that are associated with dialysis delivery. 'Single-pool' urea kinetic modeling was assessed by the Ureakin) software and the second-generation equation which uses a logarithmic estimate of spKt/V. 'Equilibrated' Kt/V (eKt/V) was calculated using the rate adjustment equation. The prescribed dose was derived using the manufacturer's specifications of the dialyzer clearance, prescribed time, actual delivered blood and dialysate flow, and estimates of volume of urea distribution. A total of 78 consecutive spKt/V measurements were obtained in 24 patients. The mean urea reduction ratio was 51 +/- 1%. The delivered spKt/V was significantly lower than that prescribed (0.87 +/- 0.03 or 0.83 +/- 0.03 vs. 1.28 +/- 0.05; p = 0.0001). The equilibrated Kt/V was markedly lower than the delivered spKt/V (0.73 +/- 0.03 vs. 0.83 +/- 0.03; p = 0.0001). Univariate analyses demonstrated that female gender, low body mass index, low predialysis weight, use of cellulose acetate dialyzers, and increased prescribed time were associated with increased odds of prescribed spKt/V > or =1.2. Similarly, old age, increased delivered time, and high cytokine production were associated with increased odds of delivered spKt/V > or =1.2. In summary, while the impact of delivered intermittent hemodialysis on the survival of patients with ARF remains to be determined, these results indicate that dialysis delivery is suboptimal in ARF, and empiric dosing should strongly consider factors related to lean body mass, including age and gender.

Nutrition in hemodialysis patients previously on a supplemented very low protein diet

BACKGROUND

Nutritional safety of protein-restricted diets in patients with chronic renal failure is controversial. In the present study, we have assessed the evolution of nutritional status after initiation of hemodialysis in patients previously treated by a supplemented very low protein diet (SVLPD).

METHODS

Nutritional data were prospectively collected during the first year of hemodialysis from 15 consecutive patients treated with a SVLPD (0.3 g protein/kg/day supplemented with essential amino acids, calcium, iron, and vitamins) and compared to 15 age- and gender-matched end-stage renal disease (ESRD) patients previously on a less-restricted diet (0.90 +/- 0.21 g protein/kg/day) who started hemodialysis during the same period. Dual-energy x-ray absorptiometry (DEXA) was used to assess body composition at 0, 6, and 12 months. Hemodialysis prescriptions, biologic data and 3-day food records were collected every 3 months.

RESULTS

Protein intake was higher than 1.2 g/kg/day in both groups as soon as 3 months after the start of hemodialysis. Albumin and prealbumin increased significantly during the first 6 months in all patients. Body mass index (BMI) increased in all patients (+0.97 +/- 1.31 kg/m2; P < 0.001) reflecting a gain in fat mass in the overall population (+2.36 +/- 2.94 kg/m2; P < 0.001) while lean body mass remained stable overall.

CONCLUSION

Once on hemodialysis, SVLPD patients rapidly increased protein intake. Nutritional status improved in all patients, with a gain in fat mass in all, and a gain in lean body mass in SVLPD men only. These data indicate that treatment with a SVLPD prior to hemodialysis initiation is nutritionally safe.

On-line monitoring of solutes in dialysate using absorption of ultraviolet radiation: technique description

PURPOSE

The aim of this work was to describe a new optical method for monitoring solutes in a spent dialysate using absorption of UV radiation.

METHOD

The method utilises UV-absorbance determined in the spent dialysate using a spectrophotometrical set-up. Measurements were performed both on collected dialysate samples and on-line. During on-line monitoring, a spectrophotometer was connected to the fluid outlet of the dialysis machine, with all spent dialysate passing through a specially-designed cuvette for optical single-wavelength measurements. The concentrations of several substances of various molecular sizes, electrical charge, transport mechanism, etc. were determined in the dialysate and in the blood using standard laboratory techniques. The correlation coefficient between UV-absorbance of the spent dialysate and concentration of the substances in the spent dialysate and in the blood was calculated from data based on the collected samples.

RESULTS

The obtained on-line UV-absorbance curve demonstrates the possibility to follow a single hemodialysis session continuously and to monitor deviations in the dialysator performance using UV-absorbance. The experimental results indicate a very good correlation between UV-absorbance and several small waste solutes removed such as urea, creatinine and uric acid in the spent dialysate and in the blood for every individual treatment at a fixed wavelength of 285 nm. Moreover, a good correlation between the UV-absorbance and substances like potassium, phosphate and beta2-microglobulin was obtained. The lowest correlation was achieved for sodium, calcium, glucose, vitamin B12 and albumin.

CONCLUSIONS

A technique for on-line monitoring of solutes in the spent dialysate utilising the UV-absorbance was developed. On-line monitoring during a single hemodialysis session exploiting UV-absorbance represents a possibility to follow a single hemodialysis session continuously and monitor deviations in dialysis efficiency (e.g. changes in blood flow and clearance). The UV-absorbance correlates well to the concentration of several solutes known to accumulate in dialysis patients indicating that the technique can be used to estimate the removal of retained substances.

Hyperhomocysteinemia and its relationship to cardiovascular disease in ESRD: influence of hypoalbuminemia, malnutrition, inflammation, and diabetes mellitus

BACKGROUND

In the general population, a mildly elevated plasma total homocysteine (tHcy) level is an independent and graded risk factor for cardiovascular disease (CVD). In patients with end-stage renal disease (ESRD), CVD is highly prevalent and a major cause of premature mortality, and plasma tHcy levels are as much as three to four times greater than in the general population. Several other risk factors, such as diabetes mellitus (DM), inflammation, and malnutrition, also are prevalent and contribute to CVD in patients with ESRD, and there are strong associations between inflammation, malnutrition, and hypoalbuminemia in these patients. Several investigations in patients with ESRD have shown the important role of vitamin status for plasma tHcy, but little attention has been given to the influence of nutritional status. However, it is obvious that hypoalbuminemia is of interest because a substantial fraction of tHcy (>70%) is protein bound, mainly to albumin.

RESULTS

In studies of patients with ESRD in whom the prevalence of hyperhomocysteinemia was very high (>90%), tHcy level was strongly related to serum albumin level, and patients with malnutrition had lower levels of both tHcy and serum albumin than those with normal nutritional status. Furthermore, inflammation, DM, and CVD are associated with hypoalbuminemia and therefore a lower degree of hyperhomocysteinemia. In our studies, in different groups of patients with ESRD, we showed that greater tHcy levels were associated with lower CVD mortality. However, this apparently paradoxical association between lower CVD mortality and lower plasma tHcy levels (although still abnormally high) does not refute the concept that hyperhomocysteinemia is a risk factor for CVD because almost all patients may have had long-standing elevated plasma tHcy levels within a range that makes them prone to develop atherosclerosis. Instead, a potentially detrimental effect of hyperhomocysteinemia on CVD in patients with ESRD may be obscured by the influence of hypoalbuminemia, whatever the cause, because hypoalbuminemia and its causes are strong predictors of mortality.

CONCLUSION

Our findings imply that nutritional status and serum albumin level, as well as the presence of inflammation and DM, should be taken into consideration when evaluating tHcy as a risk factor for CVD in patients with ESRD.

Hypoalbuminemia in acute illness: is there a rationale for intervention? A meta-analysis of cohort studies and controlled trials

OBJECTIVE

To determine whether hypoalbuminemia is an independent risk factor for poor outcome in the acutely ill, and to assess the potential of exogenous albumin administration for improving outcomes in hypoalbuminemic patients.

SUMMARY BACKGROUND DATA

Hypoalbuminemia is associated with poor outcomes in acutely ill patients, but whether this association is causal has remained unclear. Trials investigating albumin therapy to correct hypoalbuminemia have proven inconclusive.

METHODS

A meta-analysis was conducted of 90 cohort studies with 291,433 total patients evaluating hypoalbuminemia as an outcome predictor by multivariate analysis and, separately, of nine prospective controlled trials with 535 total patients on correcting hypoalbuminemia.

RESULTS

Hypoalbuminemia was a potent, dose-dependent independent predictor of poor outcome. Each 10-g/L decline in serum albumin concentration significantly raised the odds of mortality by 137%, morbidity by 89%, prolonged intensive care unit and hospital stay respectively by 28% and 71%, and increased resource utilization by 66%. The association between hypoalbuminemia and poor outcome appeared to be independent of both nutritional status and inflammation. Analysis of dose-dependency in controlled trials of albumin therapy suggested that complication rates may be reduced when the serum albumin level attained during albumin administration exceeds 30 g/L.

CONCLUSIONS

Hypoalbuminemia is strongly associated with poor clinical outcomes. Further well-designed trials are needed to characterize the effects of albumin therapy in hypoalbuminemic patients. In the interim, there is no compelling basis to withhold albumin therapy if it is judged clinically appropriate.

Acute renal failure in the ICU: assessing the utility of continuous renal replacement

Acute renal failure (ARF) in the ICU patient still remains a common problem and is associated with increased morbidity, mortality, and cost. Potential advantages of continuous renal replacement (CRRT), compared with intermittent hemodialysis (IHD) include enhanced hemodynamic stability, increased solute removal, and greater ultrafiltration. Although it was hoped that CRRT would lead to improvement in patient outcomes, there are few prospective, randomized clinical studies comparing this modality with conventional hemodialysis in the treatment of patients with ARF. The difficulties associated with designing such prospective studies are the complex status of the medical patients and the ethical dilemma of randomizing patients to a certain dialysis modality. At this time, there is no evidence to support the assertion that CRRT improves clinical outcomes compared with IHD.

Survival of hemodialysis patients and uremic toxin removal

Uremic toxin removal based on diffusion and/or convection allows eliminating solutes with negative metabolic impact. Uremic solutes can be classified as small and water-soluble compounds, larger "middle" molecules, or protein bound solutes. The question arises whether more removal of each of these solute classes affects patient survival. Kt/V of urea is currently used as a surrogate for small water-soluble solute removal. There is ample evidence that Kt/V and survival are correlated, but the threshold Kt/V remains a matter of debate. Probably, the actually proposed threshold of 1.2 is too low. This impact of Kt/V is in contradiction with the low toxicity of urea and points to a role for other water-soluble solutes, e.g., potassium. More removal of middle molecules results in a lower morbidity and also in a lower mortality. In addition, a relationship has been demonstrated between the use of membranes with large pore size and a decrease of inflammatory status, by itself an important factor related to mortality. One of the problems is that large pore membranes are at the same time more biocompatible and reflect more dialysate impurities, compared to many small pore membranes, whereas they also reflect more dialysate impurities. It remains uncertain which one of these factors, if any, has a predominant effect. Recent studies point to a separate effect of pore size but await confirmation. Protein bound toxins inhibit several biochemical functions. Their removal pattern is totally different from that of classical markers such as urea. In analogy with drugs, it is essentially the free unbound fraction that exerts biological action; this free fraction is inversely related to serum albumin, another inflammatory marker related to survival. In a final section of this presentation, attention will be drawn to the relationship in uremic patients between inflammation, malnutrition, cardiovascular disease, and mortality, and some of the potential culprits are discussed. Virtually all of these molecules have a high molecular weight or are protein bound. It is concluded that both small and middle molecule removal have an impact on survival, so that more than urea removal alone should be pursued.

Prescribing hemodialysis: the role of gender

Mortality rates remain high in the United States for people who depend on artificial kidney replacement for their existence, and the mortality rates are similar in men and women. However, women differ from men in many respects; some of these ways may have an impact on the response to dialysis through mechanisms that need to be further explored. Observational studies have shown that women respond more readily to a higher dose of dialysis, and recent data from the HEMO clinical trial suggest that women respond to an increase in clearance of low-molecular-weight uremic toxins, whereas men do not. If the findings of these studies prove to be accurate, then we may conclude not only that women require a higher dose of dialysis as currently measured, but we might also expect women to require dialysis sooner during the course of a progressive decline in renal function. The reason for this gender-dependent difference in susceptibility escapes definition at the present time, but size is an obvious confound that can be explored by using current data and in future studies. More detailed analyses of the HEMO data are forthcoming and may shed further light on this question.

Nutritional status assessed from anthropometric measures in the HEMO study

OBJECTIVE

Anthropometric methods are screening techniques for assessing nutritional stores of fat and lean tissues among persons with renal disease. This report presents cross-sectional baseline data on anthropometric indicators of nutritional status from a group of hemodialysis patients in a multicenter clinical trial, the Hemodialysis (HEMO) Study.

DESIGN

The HEMO Study is a prospective, multicenter, randomized, 2 x 2 factorial clinical trial to evaluate the efficacy of the delivered dose of dialysis, defined by Kt/V, and membrane flux in reducing morbidity and mortality in (maintenance) hemodialysis patients. Standardized measures of weight, stature, body mass index (BMI), arm and calf circumference, and triceps and subscapular skinfolds were taken immediately after dialysis. The analytic methods consisted of univariate statistics, including means, standard deviations, and selected percentiles presented as tables of descriptive statistics. Study findings were compared with corresponding national reference data from the Second National Health and Nutrition Examination Survey (NHANES II).

PATIENTS

Eligible patients between 18 and 80 years of age on chronic hemodialysis for at least 3 months, receiving hemodialysis 3 times per week and with a residual renal clearance of < 1.5 mL/min were examined. Patients also had to be able to attain an eKt/V of > or = 1.45 in 4.5 hours or an anthropometric volume < 45 to 50 L thus excluding persons with body weights over about 85 kg. The study sample consisted of the first 1,000 randomized patients, 464 men and 536 women; 642 blacks, 318 whites; and 40 of other racial backgrounds out of 1,847 randomized.

RESULTS

Differences in nutritional status by sex, race, duration of dialysis, and comorbid disease were found among these patients enrolled in the HEMO Study. In comparison with NHANES II, these hemodialysis patients were, on average, lighter with less adipose and muscle tissue than healthy persons of the same ages. These findings can be indicators of persons with chronic disease. Those with diabetes were overweight based on their BMI values.

CONCLUSION

These HEMO Study data provide a clinical reference for the use of these anthropometric indicators in assessing the nutritional status of contemporary hemodialysis patients weighing < 85 kg.

Neuropeptide-Y and atrial natriuretic peptide as prognostic markers in patients on hemodialysis

We conducted a study of the influence of the vasoactive peptides atrial natriuretic peptide (ANP) and neuropeptide Y (NPY) on survival of patients on hemodialysis and their association and relative importance with cardiac and clinical variables. Thirty-three hemodialysis patients were characterized by age, sex, diagnosis, blood pressure, serum (S)-albumin, serum (S)-urea, hemoglobin, dialysis dose, weight gain, duration of dialysis, cardiac hypertrophy, volume, failure, and ischemia and plasma levels of ANP and NPY. The outcomes were analyzed for early deaths (< 1 year) and for all deaths. The association of the variables to early deaths and all deaths, respectively, was studied in Cox proportional hazard analyses. The variables were also studied in three hierarchical steps: clinical variables only, clinical and cardiac variables, and all variables. For all deaths, the independent variables were plasma NPY (pmol/L) (hazard ratio [HR] = 1.035, p = 0.004), heart volume (ml/m2) (HR = 1.009, p = 0.001), and S-albumin (g/L) (HR = 0.750, p = 0.034). For early deaths, the independent variables were predialysis ANP (pmol/L) (HR = 1.008, p = 0.034) and NPY (pmol/L) (HR = 1.031, p = 0.026). In the hierarchical study, excluding the vasoactive peptides, heart volume, heart failure and S-albumin were independently associated with all deaths, and mean arterial blood pressure was associated with early death. When also excluding the cardiac parameters, S-albumin was associated with all deaths and mean arterial blood pressure with early death. In conclusion, plasma levels of the vasoactive peptides ANP and NPY are the most important group in a hierarchy of variables that predict imminent death in hemodialysis patients, and NPY is associated with late death. ANP and NPY apparently sum up the detrimental influence of many factors in hemodialysis patients.

Normalized protein nitrogen appearance is correlated with hospitalization and mortality in hemodialysis patients with Kt/V greater than 1.20

OBJECTIVES

Normalized protein nitrogen appearance (nPNA), also known as protein catabolic rate (nPCR), reflects the daily protein intake in maintenance hemodialysis (MHD) patients. Several studies indicate that nPNA and Kt/V correlate with clinical outcome and also with each other. Thus, the relationship between low nPNA and poor outcome could be due to uremia, low Kt/V or due to reported mathematical coupling between nPNA and Kt/V. We therefore investigated whether nPNA is associated with outcome in patients who have adequate or high Kt/V.

DESIGN

Prospective cohort.

SETTINGS

Outpatient dialysis unit affiliated with a tertiary-care community medical center.

PATIENTS

From a pool of 135 MHD outpatients in one dialysis unit, 122 patients with a delivered, Kt/V(sp)>1.20, independent of their residual renal function, were evaluated. Patients (61 women, 61 men), aged from 23 to 89 years (53.4+/-14.0 years)(+/-SD), had been undergoing MHD for one month to 17 years.

INTERVENTION

Review of laboratory values and clinical outcome.

MAIN OUTCOME MEASURES

Twelve-month mortality and hospitalization.

RESULTS

Delivered Kt/V(sp) ranged from 1.23 to 2.71 (1.77+/-0.34), nPNA from 0.5 to 2.15 (1.13+/-0.29 g/kg/day), and serum albumin, from 1.9 to 4.6 (3.76+/-0.37 g/dL). During the 12-month follow-up, 55 patients were hospitalized overnight at least once; 12 patients died; 5 patients underwent renal transplantation, and 6 patients left the study. The nPNA and Kt/V(sp) did not correlate significantly (r=.09) except when analysis was limited to Kt/V values < 1.5 (r=.54). Serum nPNA and albumin were the only variables with statistically significant correlations with both mortality and 3 measures of hospitalization (H): total days of H (H(D)), total number of H (H(F)), and time to first H (H(T)). The case-mix adjusted correlations for serum albumin and nPNA versus total days (r(HD)) and frequency of H (r(HF)) were significant, and Cox analysis based on H(T) and time to death resulted in significant odds ratios for each standard deviation decrement for both serum albumin and nPNA. Serum total iron binding capacity (TIBC) and creatinine concentrations also correlated with some but not all outcome measures: lower serum concentrations of these values were each significantly associated with poor clinical outcomes.

CONCLUSIONS

Both nPNA and serum albumin predict prospective hospitalization and mortality in MHD patients with Kt/V > 1.20. Serum TIBC and creatinine concentrations appear to have association with some outcome measures as well. These data are consistent with the possibility that protein intake affects the clinical course even in the setting of an adequate to high hemodialysis dose. Studies based on randomized assignments to different protein intakes would be helpful to confirm these conclusions.

Effects of high-flux hemodialysis on oxidant stress

BACKGROUND

Neutrophil oxygen radical production is increased in end-stage renal disease (ESRD) patients and it is further enhanced during dialysis with low-flux cellulosic membranes. This increased oxygen radical production may contribute to the protein and lipid oxidation observed in ESRD patients. We tested the hypothesis that high-flux hemodialysis does not increase oxygen radical production and that it is not associated with protein oxidation.

METHODS

Neutrophil oxygen radical production was measured during dialysis with high-flux dialyzers containing polysulfone and cellulose triacetate membranes. Free sulfhydryl and carbonyl groups and advanced oxidation protein products were measured to assess plasma protein oxidation.

RESULTS

Pre-dialysis, neutrophil oxygen radical production was significantly greater than normal and increased significantly as blood passed through the dialyzer in the first 30 minutes of dialysis. Post-dialysis, however, neutrophil oxygen radical production had decreased and was not different from normal. Pre-dialysis, significant plasma protein oxidation was evident from reduced free sulfhydryl groups, increased carbonyl groups, and increased advanced oxidation protein products. Post-dialysis, plasma protein free sulfhydryl groups had increased to normal levels, while plasma protein carbonyl groups increased slightly, and advanced oxidation protein products remained unchanged.

CONCLUSIONS

The results of this study show that neutrophil oxygen radical production normalizes during high-flux dialysis, despite a transient increase early in dialysis. This decrease in oxygen radical production is associated with an improvement in some, but not all, measures of protein oxidation.

Effect of dialysis dose and membrane flux in maintenance hemodialysis

BACKGROUND

The effects of the dose of dialysis and the level of flux of the dialyzer membrane on mortality and morbidity among patients undergoing maintenance hemodialysis are uncertain.

METHODS

We undertook a randomized clinical trial in 1846 patients undergoing thrice-weekly dialysis, using a two-by-two factorial design to assign patients randomly to a standard or high dose of dialysis and to a low-flux or high-flux dialyzer.

RESULTS

In the standard-dose group, the mean (+/-SD) urea-reduction ratio was 66.3+/-2.5 percent, the single-pool Kt/V was 1.32+/-0.09, and the equilibrated Kt/V was 1.16+/-0.08; in the high-dose group, the values were 75.2+/-2.5 percent, 1.71+/-0.11, and 1.53+/-0.09, respectively. Flux, estimated on the basis of beta2-microglobulin clearance, was 3+/-7 ml per minute in the low-flux group and 34+/-11 ml per minute in the high-flux group. The primary outcome, death from any cause, was not significantly influenced by the dose or flux assignment: the relative risk of death in the high-dose group as compared with the standard-dose group was 0.96 (95 percent confidence interval, 0.84 to 1.10; P=0.53), and the relative risk of death in the high-flux group as compared with the low-flux group was 0.92 (95 percent confidence interval, 0.81 to 1.05; P=0.23). The main secondary outcomes (first hospitalization for cardiac causes or death from any cause, first hospitalization for infection or death from any cause, first 15 percent decrease in the serum albumin level or death from any cause, and all hospitalizations not related to vascular access) also did not differ significantly between either the dose groups or the flux groups. Possible benefits of the dose or flux interventions were suggested in two of seven prespecified subgroups of patients.

CONCLUSIONS

Patients undergoing hemodialysis thrice weekly appear to have no major benefit from a higher dialysis dose than that recommended by current U.S. guidelines or from the use of a high-flux membrane.

Mortality risk in hemodialysis patients and changes in nutritional indicators: DOPPS

BACKGROUND

Nutritional status is strongly associated with outcomes among hemodialysis patients. We analyzed the independent predictive value of several readily measured nutritional indicators, including a modified subjective global assessment (mSGA), body mass index (BMI), serum albumin, serum creatinine, normalized protein catabolic rate (nPCR), serum bicarbonate, lymphocyte count, and neutrophil count, using baseline and six-month follow-up measurements.

METHODS

The study sample consisted of 7719 U.S. adult hemodialysis patients enrolled in the international Dialysis Outcomes and Practice Patterns Study (DOPPS), a prospective observational study that includes a random sample of hemodialysis patients from 145 dialysis facilities in the United States. Cox regression was used to estimate the relative risk of mortality associated with differences in measurements at baseline and six months later. Each analysis was adjusted for age, race, sex, and 15 summary comorbid conditions.

RESULTS

Lower baseline measurements of mSGA, BMI, serum albumin, serum creatinine, and lymphocyte count were independently associated with significantly higher risk of mortality. During six-month follow-up, decreases in BMI, serum albumin, and serum creatinine were also associated with significantly higher mortality risk. The risk of mortality increased with higher baseline and six-month increases in neutrophil count.

CONCLUSIONS

This study confirms that several readily-measured nutritional indicators predict mortality among hemodialysis patients and that changes in indicator values over six months provide additional important prognostic information. Interventions that modify these indicators of nutritional status may have an important impact on the survival of hemodialysis patients.

Anemia treatment in the pre-ESRD period and associated mortality in elderly patients

BACKGROUND

Anemia is a common complication of advancing chronic kidney disease, yet little is known about the consistency of anemia treatment before end-stage renal disease (ESRD) and mortality on dialysis therapy.

METHODS

We studied 89,193 incident Medicare patients with ESRD in 1995 to 1997 aged 67 plus years with claims 2 years before their dialysis therapy initiation. Patients were classified as follows: no epoetin, 25% or less (least consistent), greater than 25% to 50%, greater than 50% to 75%, and greater than 75% (most consistent) epoetin treatment in the available months from the first pre-ESRD epoetin dose to the first ESRD service date. Cox regression modeled the risk for 1-year death in the post-ESRD period, adjusting for age, sex, race, diabetic status, albumin level, and incidence year.

RESULTS

Sixty percent of patients had hematocrits less than 30% at ESRD initiation, yet only 15.6% (N = 13,877) had epoetin claims before ESRD. The most consistent epoetin treatment group had hematocrits increase from 27.5% to 30.8% (P < 0.0001) by month 4 of treatment. Patients with the most consistent epoetin treatment had a greater mean hematocrit (29.2% +/- 0.11%; P < 0.0001) and albumin level (3.31 +/- 0.01 g/dL [33.1 g/L]) at initiation than those with the least consistent treatment (28.1% +/- 0.10% and 3.21 +/- 0.01 g/dL [32.1 g/L], respectively). The relative risk for death in patients with the least consistent versus the most consistent (the reference) epoetin treatment was 1.460 (95% CI, 1.245 to 1.713; P < 0.0001) 1 year after the first ESRD service date.

CONCLUSION

Elderly patients with consistent pre-ESRD epoetin treatment had lower risks for death in the first year of dialysis therapy after ESRD initiation.

The relative predictive ability of four different measures of hemodialysis dose

BACKGROUND

The amount of hemodialysis that patients receive is an independent predictor of mortality. However, the relative predictive ability of four common measures of dialysis dose (urea reduction ratio, single-pool Kt/V, double-pool Kt/V, and urea index) is unclear.

METHODS

Using The Renal Network Data System, we identified 14,810 incident hemodialysis patients in Indiana, Kentucky, Ohio, and Illinois from 1997 to 2000. We calculated each measure of hemodialysis dose during the first 6 months of treatment, then prospectively followed up patients for an additional 6 months. For each measure of dialysis dose, we developed a logistic regression model to examine the relationship between dose and patient mortality after adjustment for age, race, sex, cause of renal failure, comorbid conditions, and albumin level. We compared the predictive ability of the four models using the c statistic, a measure of how frequently survivors have a lower predicted probability of death compared with nonsurvivors. C statistics can vary from 0.50 (no predictive ability) to 1.00 (perfect predictive ability).

RESULTS

Of all patients, 11.3% died during follow-up. Mortality was independently associated with low dialysis dose, advanced age, white race, female sex, specific comorbid conditions, and low albumin level. All four predictive models had virtually identical c statistics (range, 0.69 to 0.70).

CONCLUSION

Models including hemodialysis dose and patient characteristics have a modest ability to predict mortality. Moreover, all four measures of dialysis dose have an equivalent predictive ability. Decisions to use a specific measure should be based on other considerations, such as ease of use, need to troubleshoot inadequate dialysis delivery, or research on urea kinetics or nutritional factors.

Association of serum albumin and atherosclerosis in chronic hemodialysis patients

BACKGROUND

Because cardiovascular disease is the leading cause of death and hypoalbuminemia predicts mortality, hypoalbuminemia may be associated with atherosclerosis.

METHODS

In 1,411 patients enrolled in the HEMO study, associations of albumin with the presence of coronary artery disease (CAD), cerebrovascular disease (CVD), peripheral vascular disease (PVD), and any one of the three conditions at baseline were examined using multivariable logistic regression models.

RESULTS

In the two-slope model, when albumin level was 3.6 g/dL (36 g/L) or greater, with each 1-g/dL (10-g/L) increase in albumin level the odds for CAD (odds ratio [OR], 0.32; 95% confidence interval [CI], 0.17 to 0.59), PVD (OR, 0.39; 95% CI, 0.18 to 0.80), CVD (OR, 0.33; 95% CI, 0.15 to 0.73), and any one of the three conditions (OR, 0.23; 95% CI, 0.12 to 0.44) decreased. When albumin level was less than 3.6 g/dL (36 g/L), none of the conditions was statistically significantly associated with each 1-g/dL (10-g/L) increase in albumin level. When normal- and low-albumin groups were compared with each other, patients with albumin levels less than 3.6 g/dL (36 g/L) had a higher association with CAD (OR, 1.32; 95% CI, 1.03 to 1.70) and for any one of the three conditions (OR, 1.38; 95% CI, 1.07 to 1.78).

CONCLUSION

The odds for atherosclerosis linearly decreased as albumin level increased in the normal-albumin group, and a plateau was seen in the low-albumin group; however, the low-albumin group had significantly greater CAD. The nonlinearity of association of albumin level with prevalence of atherosclerosis might be due to the cross-sectional nature of the study of higher mortality with hypoalbuminemia.

New empiric expressions to calculate single pool Kt/V and equilibriated Kt/V

Most formulae used for Kt/V computations are cumbersome and require variables that are not always available. Even the simplest models involve urea distribution volume or patient postdialysis weight. Calculating urea reduction ratio (URR) is easier and does not require additional variables, but it fails to account for residual renal function or for the removal of urea when urea levels do not change, e.g., during ultrafiltration. The goal of this study was to derive new expressions to calculate Kt/V based on URR using bivariate and multivariate linear and nonlinear models, with the URR adjusted for ultrafiltration volume and time on dialysis. Models were derived from a database of 598 dialysis records with a mean spKt/V of 1.6 (range 0.74-2.8). Models were validated on the same dataset that they were derived from and a separate dataset consisting of 17,190 dialysis records. The validation was made by comparing the empirically derived models with the Gotch and Daugirdas formulae. Among our empirically derived expressions, the closest approximation of the "gold standard," Kt/V, is the multivariate linear model of URR adjusted for ultrafiltration volume. When information about ultrafiltration is not available, the bivariate exponential formula can be successfully used to estimate Kt/V.

The other side of the coin: impact of toxin generation and nutrition on the uremic syndrome

Both the morbidity of the uremic syndrome and the generation of uremic toxins are attributed to malnutrition. If protein intake and catabolism result in the generation of solutes, then nutritional intake should be related directly to toxicity. On the other hand, inadequate nutrition has been linked to inflammation and mortality. It remains difficult to reconcile these two lines of thought. Several possibilities exist that might account for this apparent paradox: 1) not all nutritional and protein degradation products are toxic; 2) toxins generated from increased protein intake are removed if protein intake is linked to dialysis dose; 3) albumin acts as a buffer for toxicity-hypoalbuminemia favors liberation of protein-bound toxins from their binding sites, enhancing their toxicity; 4) solutes generated from tissue breakdown are more toxic than those generated by nutritional protein; 5) both high and low concentrations of solutes have a negative impact; 6) toxic compounds unrelated to protein breakdown are specific causes of malnutrition and inflammation; 7) and/or residual renal function plays a key role in the elimination of compounds discussed under possibility 6. Thus the uremic syndrome should be considered as a potentially fatal interaction among inflammation, malnutrition, low levels of albumin in the plasma, accumulated protein-bound solutes and generation of nonnutritionally related toxins. Not only optimal dialysis, but also optimal nutritional intake and optimal utilization of these nutrients should help neutralize this chain of events.

Comparing mortality of elderly patients on hemodialysis versus peritoneal dialysis: a propensity score approach

The objective of this study was to evaluate differences in mortality over the first year of renal replacement therapy (RRT) between elderly patients starting treatment on hemodialysis (HD) versus peritoneal dialysis (PD). For the period of 1991 to mid-1996, this study defined an inception cohort of all patients aged >65 yr with new-onset chronic RRT who were New Jersey Medicare and/or Medicaid beneficiaries in the year before RRT and who had been diagnosed with renal disease more than 1 yr before RRT. Propensity scores were calculated for first treatment assignment from a large number of baseline covariates. Mortality was then compared among patients initially assigned to HD versus PD using multivariate 90-d interval Cox models controlled for propensity scores and center stratification. Peritoneal dialysis starters had a 16% higher rate of death during the first 90 d of RRT compared with HD patients (hazard ratio [HR], 1.16; 95% confidence interval [CI], 0.96 to 1.42)]. Mortality did not differ between day 91 and 180 (HR, 1.03; 95% CI, 0.71 to 1.51). Thereafter, PD starters again died at a higher rate (HR, 1.45; 95% CI, 1.07 to 1.98). These findings were more pronounced among patients with diabetes. Sensitivity analyses using more stringent criteria to ensure that first treatment choice reflected long-term treatment choice confirmed the presence of an association between PD and mortality. In conclusion, compared with HD, peritoneal dialysis appears to be associated with higher mortality among older patients, particularly among those with diabetes, even after controlling for a large number of risk factors for mortality, propensity scores to control for nonrandom treatment assignment, and center stratification.

Fructosamine assay using albumin extracted from serum

Albumin extracted from serum by a simple technique using trichloroacetic acid and ethanol has been applied to a fructosamine assay using nitroblue tetrazolium. A fructosamine assay using extracted albumin sample was carried out without interference from low molecular weight substances with reducing activities and other proteins with varying concentrations, half-lives and reducing activities. 1-Deoxy-1-p-toluidino-D-fructose (DTF) was selected as a calibrator for the assay because it is a stable Amadori reaction product with a constant glycation rate. Albumin fructosamine value was calculated using the calibration curve of DTF. The corrected albumin fructosamine value was expressed as the amount of albumin fructosamine per gram of extracted albumin taking into consideration the variation in albumin concentrations in sera from patients. The corrected albumin fructosamine values correlated more closely with the fasting blood glucose levels (r=0.735) than the serum fructosamine values corrected for albumin concentrations (r=0.514) (p<0.05).

Therapeutic effects of oral nutritional supplementation during hemodialysis

BACKGROUND

Protein-calorie malnutrition is common in chronic hemodialysis (CHD) patients and correlates with morbidity and mortality in these patients. There are limited trials evaluating the efficacy of oral nutritional supplementation in malnourished CHD patients.

METHODS

Eighty-five CHD patients with evidence of malnutrition were included in this prospective study. Patients were followed for a 3-month baseline period during which they received conventional nutrition counseling. This was followed by an intervention period, during which an oral nutritional supplement specifically formulated for CHD patients was given over a period of 6 months. An important element of this study was that the nutritional supplement was provided during dialysis to ensure compliance. Serial measurements of nutritional parameters including concentrations of serum albumin, prealbumin, transferrin as well as body mass index (BMI) and subjective global assessment (SGA) were obtained during the 9-month period.

RESULTS

The nutritional parameters did not change during the 3-month baseline period. Following administration of oral supplementation during hemodialysis, there were significant increases in concentrations of serum albumin (from 3.33 +/- 0.32 g/dL at baseline, to 3.65 +/- 0.26 g/dL at month 6, P < 0.0001) and serum prealbumin (from 26.1 +/- 8.6 mg/dL at baseline, to 30.7 +/- 7.4 mg/dL at month 6, P = 0.002). Mean SGA score increased 14% by the end of the study (P = 0.023). Although BMI and estimated dry weight increased also, these changes were not statistically significant. Serum transferrin did not change during the study period.

CONCLUSION

Oral nutritional supplementation given during hemodialysis improves nutritional markers in malnourished CHD patients.

Measuring the efficacy of a quality improvement program in dialysis adequacy with changes in center effects

End-stage renal disease (ESRD) patients treated with hemodialysis have a high mortality rate, which is largely due to inadequate dialysis. Dialysis adequacy, measured by the urea reduction ratio (URR), tends to be correlated within dialysis facilities with wide variations in average center adequacy. These are characteristics of a center effect, which can have an important impact on dialysis adequacy. This study measured the center effect observed in an ESRD Network before and after a successful quality improvement project (QIP). URR values were recorded on patients sampled from 196 facilities in ESRD Network 6 before (pre-QIP, n = 5309) and after (post-QIP, n = 5753). These data was used to determine the within center correlation (rho) of individual URR values and between center variation in aggregate URR values in both samples. The overall mean URR improved from the pre- to post-QIP sample (mean URR 64.7 +/- 0.1 versus 69.8 +/- 0.1, respectively; P = 0.001). There was a high degree of within center correlation in dialysis adequacy across the facilities, which significantly diminished post-QIP (rho, 0.15 [95% CI, 0.12 to 0.18] versus rho, 0.06 [95% CI, 0.04 to 0.08]). The between center variation in mean URR also declined from the pre-QIP to the post-QIP sample (SD, 3.6 versus 2.8). In conclusion, there is a center effect on dialysis adequacy measurable in an ESRD Network, which diminishes after a successful QIP; therefore, when implementing a QIP to improve dialysis adequacy, changes in the center effect should be considered a potential indicator of the efficacy of the intervention.

Effects of hemodialysis dose on anemia, hypertension, and nutrition

There is good evidence that by improving dialysis adequacy, morbidity, and mortality of hemodialysis (HD) patients decrease. Dialysis adequacy has also been related to the better control of arterial blood pressure (BP), anemia and improvement of patients' nutritional status. This is a self-control study of 34 HD patients, (23 males, 11 females), aged 52.6 +/- 15.5 years, HD duration 55.9 +/- 61.2 months, referring to the effect of increasing delivered dialysis dose, over a two-year period, on their clinical and laboratory parameters. Delivered HD dose increased statistically significantly: Urea reduction ratio (URR) increased from 52 +/- 8 to 71 +/- 7% and Kt/V from 0.93 +/- 0.19 to 1.55 +/- 0.29 (p < 0.001). Hb increased statistically significantly from 10.4 +/- 1.7 to 11.0 +/- 1.3 g/dL (p < 0.05) while no difference has been noticed in weekly EPO dose. Both systolic and diastolic BP decreased statistically significantly (from 147 +/- 24 to 133 +/- 25mmHg and from 73 +/- 12 to 66 +/- 13 mmHg respectively, p = 0.001). Serum albumin increased from 4.3 +/- 0.4 to 4.6 +/- 0.3g/dL (p = 0.002) and nPCR from 0.93 +/- 0.16 to 1.20 +/- 0.17 (p < 0.001). We conclude that increasing dialysis dose results in both clinical and laboratory improvement regarding hypertension, nutritional status and control of HD patients' anemia.

Malnutrition in hemodialysis diabetic patients: evaluation and prognostic influence

BACKGROUND

This work aimed to evaluate the role of malnutrition in the increased mortality rate of hemodialysis diabetic patients from a French cooperative series.

METHODS

Body mass index (BMI), serum albumin, prealbumin, cholesterol, and pre-dialysis creatinine, normalized protein catabolic rate and lean body mass (LBM) were measured in 734 diabetic and 6389 non-diabetic patients (aged 63.4 +/- 12.2 and 62.0 +/- 15.9 years; 1.01 male to 1.40 female ratio). The outcome of 1610 of these patients, including 170 diabetics, was assessed during a 30-month follow-up.

RESULTS

Diabetic as compared to non-diabetic patients showed a significant (P < 10-4) increased BMI (25.9 +/- 5.2 vs. 23.1 +/- 4.3) and cholesterol (5.5 +/- 1.6 vs. 5.3 +/- 1.5 mmol/L), and decreased albumin (37.8 +/- 5.4 vs. 38.9 +/- 5.3 g/L), prealbumin (317 +/- 91 vs. 340 +/- 94 mg/L), creatinine (711 +/- 184 vs. 816 +/- 217 micromol/L) and LBM (76 +/- 18 vs. 87 +/- 21%). Normalized protein catabolic rate was similar in the two groups (1.11 +/- 0.31 vs. 1.13 +/- 0.32 g/kg/L). One and two-year survival was 83.7 +/- 2.9% and 65.5 +/- 3.8% in diabetic patients versus 90.3 +/- 0.8% and 79.9 +/- 1.1% in non-diabetics (relative risk 1.26, P < 0.01). Independent predictors of survival were age, albumin and prealbumin in non-diabetics and only age in diabetics.

CONCLUSION

Diabetic patients compared to non-diabetics were characterized by an increased incidence of protein malnutrition and decreased survival. However, the higher death risk associated with diabetes was not related to malnutrition.

Increased risk for cardiovascular mortality among malnourished end-stage renal disease patients

BACKGROUND

Studies have shown that protein-energy malnutrition (PEM) is a strong predictor of total mortality among patients with end-stage renal disease (ESRD). The aim of this study is to assess the relationship between nutritional indices and cardiovascular (CV) mortality among patients with ESRD by using data from the US Renal Data System (USRDS) Dialysis Morbidity and Mortality Study Wave I (DMMS-1).

METHODS

Demographic and medical data were abstracted from 5,058 patients who participated in the USRDS DMMS-1. Nutritional measurements of interest included subjective assessment of malnutrition, serum albumin level, body mass index (BMI), and cholesterol level. The USRDS provided follow-up data on mortality through July 1998. The Cox proportional hazard model was used to estimate the risk for CV death associated with nutritional markers.

RESULTS

The risk for CV death was 39% greater for each 1-g/dL (10-g/L) decrement in serum albumin level (95% confidence interval [CI], 1.20 to 1.60; P < 0.001). A care provider's assessment of malnutrition was associated with a 27% greater risk for CV mortality (95% CI, 1.08 to 1.50; P < 0.004). For each one-unit decrement in BMI, the risk for CV disease (CVD) was 6% greater (95% CI, 1.00 to 1.13; P < 0.046). Among patients without CVD at the study start, serum albumin level remained a significant risk factor for CV death (adjusted relative risk = 1.39 per 1-g/dL (10-g/L) increment; P = 0.026). In addition, change in albumin levels over time was significantly associated with CV mortality. For each 0.1-g/dL (1-g/L) decrement in albumin level per month, the risk for CV death was 2.24-fold greater (95% CI, 1.65 to 3.02; P < 0.001) among the entire cohort and 3.86-fold greater (95% CI, 1.96 to 7.60; P < 0.010) among those without a known history of CVD at the study start.

CONCLUSION

Both PEM at baseline and worsening PEM over time are associated with a greater risk for CV death. This finding persists among dialysis patients without preexisting CVD at baseline.

Behavior of non-protein-bound and protein-bound uremic solutes during daily hemodialysis

BACKGROUND

In the last few years, renewed interest in daily short hemodialysis (DHD; six 2-hour sessions per week) has become apparent as a consequence of the better clinical outcome of patients treated by this schedule. Uremic syndrome is characterized by the retention of a large number of toxins with different molecular masses and chemical properties. Some toxins are water soluble and non-protein bound, whereas others are partially lipophilic and protein bound. There is increased evidence that protein-bound toxins are responsible for the biochemical and functional alterations present in uremic syndrome, and the kinetics of urea is not applicable to these substances for their removal. The aim of this study is to investigate whether DHD is accompanied by increased removal of non-protein-bound and protein-bound toxins and a decrease in their prehemodialysis (pre-HD) serum levels.

PATIENTS AND METHODS

We studied 14 patients with end-stage renal disease treated by standard HD (SHD; three 4-hour sessions per week) for at least 6 months and randomly assigned them to a two-period crossover study (SHD to DHD and DHD to SHD). Patients maintained the same dialyzer, dialysate, and Kt/V during the entire study. At the end of 6 months of SHD and 6 months of DHD, we evaluated hemoglobin levels, hematocrits, recombinant human erythropoietin doses, and pre-HD and post-HD concentrations of serum urea, creatinine, uric acid, and the following protein-bound toxins: 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid, p-cresol, indole-3-acetic acid, indoxyl sulfate, and hippuric acid.

RESULTS

Values for hemoglobin, hematocrit, and recombinant human erythropoietin dose did not change during the two study periods. Pre-HD concentrations of creatinine, urea, and uric acid decreased on DHD (creatinine, from 8.7 +/- 1.9 to 7.8 +/- 1.6 mg/dL; P < 0.05; urea, from 149.4 +/- 28.8 to 132.7 +/- 40 mg/dL; P = 0.05; uric acid, from 9.14 +/- 1.49 to 8.16 +/- 1.98 mg/dL; P = 0.06). Concerning protein-bound toxins, lower pre-HD levels during DHD were reported for indole-3-acetic acid (SHD, 0.16 +/- 0.04 mg/dL; DHD, 0.13 +/- 0.03 mg/dL; P = 0.01), indoxyl sulfate (SHD, 3.35 +/- 1.68 mg/dL; DHD, 2.85 +/- 1.08 mg/dL; P = 0.02), and p-cresol at the borderline of significance (SHD, 0.96 +/- 0.59 mg/dL; DHD, 0.78 +/- 0.33 mg/dL; P = 0.07).

CONCLUSION

Such non-protein-bound compounds as uric acid, creatinine, and urea were removed significantly better by DHD, and pre-HD serum levels were reduced. Furthermore, pre-HD concentrations of some protein-bound solutes, such as indole-3-acetic acid, indoxyl sulfate, and p-cresol, also were lower during DHD.

Effects of feeding on albumin synthesis in hypoalbuminemic hemodialysis patients

BACKGROUND

Hypoalbuminemia is a powerful predictor of morbidity and mortality in hemodialysis (HD) patients and results from a reduction in albumin synthesis. It is not known if this is associated with any impairment of the normal response to feeding.

METHODS

Protein turnover and albumin synthesis were measured in the fasting and fed state using a primed constant infusion of L-[1-(13)C]leucine in seven hypoalbuminemic (albumin < or = 36 g/L) HD patients (HHD), seven normoalbuminemic (albumin > or = 40 g/L) HD patients (NHD) and nine age-matched normal controls.

RESULTS

The increase in albumin synthesis on feeding was impaired in HHD patients (fasting 15.0 +/- 1.5 vs. fed 17.7 +/- 2.9%, P = NS) compared to NHD (fasting 13.7 +/- 0.9 vs. fed 17.4 +/- 1.0%, P < 0.05) and controls (fasting 12.9 +/- 0.6 vs. fed 15.2 +/- 0.6%, P < 0.05). In addition, body mass index and percent body fat were significantly (P < 0.05) lower in HHD (20.8 +/- 1.3 kg/m2, 23.4 +/- 2.0%) than NHD (26.7 +/- 1.3 kg/m2, 33.1 +/- 3.2%) or controls (26.2 +/- 1.1 kg/m2, 32.6 +/- 1.8%). There was no difference in dietary protein or energy intake in the three groups.

CONCLUSIONS

There are differences of body composition and protein metabolism in HHD patients that may be related to an impaired metabolic response to feeding.

The effects of zinc supplementation on serum zinc and cholesterol concentrations in hemodialysis patients

OBJECTIVE

To examine the effect of zinc sulfate supplementation on the concentrations of serum zinc and serum cholesterol in hemodialysis (HD) patients.

SETTING

Outpatient dialysis center in a large metropolitan city.

DESIGN

Randomized, double-blind, before-after trial.

PATIENTS

Twenty-eight maintenance HD patients were selected. Twenty (15 women and 5 men) completed the study. Subjects were identified for inclusion in the study by the following criteria: HD treatment for a minimum of 6 months, no signs of gastrointestinal disorders, and no record of hospitalizations for reasons other than vascular access complications within the last 3 months.

INTERVENTIONS

Patients were given a daily supplement of 7.7 micromol zinc sulfate (50 mg elemental zinc) or a cornstarch placebo capsule for 90 days. Patients completed 2-day food records, at day 0 and day 90 of the study, which included 1 dialysis day and 1 nondialysis day.

MAIN OUTCOME MEASURE

Fasting, predialysis serum samples were collected on days 0, 40, and 90 to determine serum zinc and total cholesterol (TCHOL) concentrations. Dietary parameters, including zinc, protein, and energy intake, were also analyzed on days 0 and 90.

RESULTS

Initial concentrations of serum zinc indicated subjects were below the normal range for serum zinc standards (12 micromol/L [80 microg/dL]). After supplementation, subjects in the zinc-supplemented group showed significant increases in serum zinc concentrations from 0.79 microg/mL at day 0 to 0.96 microg/mL at day 90. Serum TCHOL concentrations were initially low among subjects in the control (2.914 +/- 0.158 mmol/L [112.7 +/- 6.1 mg/dL]) and zinc-supplemented (3.155 +/- 0.354 mmol/L [122.0 +/- 13.7 mg/dL]) groups. Serum TCHOL concentrations in the control group increased slightly throughout the study period but did not reach statistical significance. A progressive increase in serum TCHOL concentration was observed in the zinc-supplemented group from the beginning (3.155 +/- 0.354 mmol/L [122.0 +/- 13.7 mg/dL]) to the end (4.445 +/- 0.478 mmol/L [171.9 +/- 18.5 mg/dL]) of the study (r =.63, P <.05). Mean serum high-density lipoprotein (HDL) cholesterol concentrations for the zinc-supplemented group were 0.959 mmol/L +/- 0.11 (37.1 mg/dL +/- 4.3), 0.825 mmol/L +/- 0.08 (31.9 mg/dL +/- 3.2), and 0.908 mmol/L +/- 0.10 (35.1 mg/dL +/- 3.9) from the beginning to the end of the experimental period. The mean serum HDL cholesterol concentrations for the control group were 0.760 mmol/L +/- 0.075 (29.4 mg/dL +/- 2.9), 0.760 +/- 0.08 (29.4 mg/dL +/- 3.0), and 0.799 mmol/L +/- 0.13 (30.9 mg/dL +/- 4.9) from the beginning to the end of the experimental period. A progressive increase in low-density lipoprotein (LDL) cholesterol concentration was observed for the zinc-supplemented group throughout the study. Mean LDL cholesterol concentrations for the zinc-supplemented group were 2.19 mmol/L +/- 0.39 (85 mg/dL +/- 15.0), 3.30 mmol/L +/- 0.36 (127.8 mg/dL +/- 14.1), and 3.53 mmol/L +/- 0.53 (136.7 mg/dL +/- 20.6) from the beginning to the end of the study period. When serum zinc concentration was correlated with serum LDL cholesterol concentration, a significant correlation was found (r =.62, P <.03) for the zinc-supplemented group and no significant difference was found for the control group. No significant differences in LDL cholesterol concentrations were found within the control group from the beginning to the end of the study. Dietary intake of zinc, cholesterol, total fat, and saturated fat remained constant and did not statistically influence serum values. Reported energy intake increased significantly in the zinc-supplemented group from 5,799 kJ/24 h (1,385 kcal/d) at day 0 to 7,042 kJ/24 h (1,682 kcal/d) at day 90.

CONCLUSION

Zinc supplementation is an effective means of improving serum levels of zinc and cholesterol in the HD patient.