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

Relationship between serum protein and mortality in adults on long-term hemodialysis: exhaustive review and meta-analysis

The aim of this exhaustive review and meta-analysis was to explore the relation among serum protein, inflammatory markers, and all-cause and cardiovascular mortalities in adult patients on maintenance hemodialysis. We searched the Medline, Science Citation Index, Academic Search Premier, Cochrane Library, and Embase electronic data bases. Data extraction and quality assessment were done independently by two reviewers and results were pooled using the random effects model. Cochran's Q was used to identify heterogeneity and a funnel plot was used for assessment of publication bias. A meta-analysis was performed on 38 studies (265 330 patients) reporting on serum proteins, inflammatory markers, and mortality. A significant inverse relation was found between serum albumin and all-cause (hazard ratio [HR] 0.7038, 95% confidence interval [CI] 0.6367-0.7781) and cardiovascular (HR 0.8726, 95% CI 0.7909-0.9628) mortalities, with a significantly stronger relation with all-cause mortality (P=0.0014). Pooled results for C-reactive protein showed a weak but significant direct relation with all-cause mortality (HR 1.0322, 95% CI 1.0151-1.0496), but there was not a significant relation between C-reactive protein and cardiovascular mortality (HR 1.0172, 95% CI 0.9726-1.0639). A high degree of heterogeneity was identified among studies especially in the case of all-cause mortality. An asymmetrical funnel plot for serum albumin is suggestive of publication bias. From the meta-analysis it is concluded that serum albumin showed a significant inverse relation with all-cause and cardiovascular mortalities but the relation between prealbumin and all-cause mortality was not significant. C-reactive protein showed a significant direct relation with all-cause mortality but not with cardiovascular mortality. The potential adverse effects of malnutrition and infections in relation to mortality highlight the need for continued treatment of infections and correction of malnutrition in patients on dialysis.

Serum albumin as an outcome predictor in hospital emergency medical admissions

BACKGROUND

To examine the relationship between admission serum albumin and 30-day mortality during an emergency medical admission.

METHODS

An analysis was performed of all emergency medical patients admitted to St. James's Hospital (SJH), Dublin between 1st January 2002 and 31st December 2008, using the hospital in-patient enquiry (HIPE) system, linked to the patient administration system, and laboratory datasets. Mortality was defined as an in-hospital death within 30 days. Logistic regression was used to calculate unadjusted and adjusted odds ratios (ORs) and 95% confidence intervals for defined albumin subsets.

FINDINGS

Univariate analysis using predefined criteria based on distribution, identified the groups of <10% and between 10 and 25% of the serum albumin frequency distribution as at increased mortality risk. Their mortality rates were 31.7% and 15.4% respectively; their unadjusted odds rates were 6.35 (5.68, 7.09) and 2.11 (1.90, 2.34). Patients in the lowest 25% of the distribution had a 30-day mortality of 19.9% and this significantly increased risk persisted, after adjustment for other outcome predictors including co-morbidity and illness severity (OR 2.95 (2.49, 3.48): p<0.0001).

INTERPRETATION

Serum albumin is predictive of 30-day mortality in emergency medical patients; mortality is non-linearly related to baseline albumin. The disproportionate increased death risk for patients in the lowest 25% of the frequency distribution (<36 g/L) is not due to co-morbidity factors or acute illness severity.

Shorter dialysis times are associated with higher mortality among incident hemodialysis patients

There is an association between hemodialysis session length and mortality independent of the effects of session duration on urea clearance. However, previous studies did not consider changes in session length over time nor did they control for the influence of time-dependent confounding. Using data from a national cohort of 8552 incident patients on thrice-weekly, in-center hemodialysis, we applied marginal structural analysis to determine the association between session length and mortality. Exposure was based on prescribed session length with the outcome being death from any cause. On the 31st day after initiating dialysis, the patients were considered at-risk and remained so until death, censoring, or completion of 1 year on dialysis. On primary marginal structural analysis, session lengths <4 h were associated with a 42% increase in mortality. Sensitivity analyses showed a dose-response relationship between session duration and mortality, and a consistency of findings across prespecified subgroups. Our study suggests that shorter hemodialysis sessions are associated with higher mortality when marginal structural analysis was used to adjust for time-dependent confounding. Further studies are needed to confirm these findings and determine causality.

Reassessment of albumin as a nutritional marker in kidney disease

The decision by nephrologists, renal dietitians, federal agencies, health care payers, large dialysis organizations, and the research community to embrace serum albumin as an important index of nutrition and clinical performance is based on numerous misconceptions. Patients with analbuminemia are not malnourished and individuals with simple malnutrition are rarely hypoalbuminemic. With the possible exception of kwashiorkor, a rare nutritional state, serum albumin is an unreliable marker of nutritional status. Furthermore, nutritional supplementation has not been clearly shown to raise levels of serum albumin. The use of serum albumin as a quality care index is also problematic. It has encouraged a reflexive reliance on expensive and unproven interventions such as dietary supplements and may lead to adverse selection of healthier patients by health care providers. The authors offer a rationale for considering albumin as a marker of illness rather than nutrition. Viewed in this manner, hypoalbuminemia may offer an opportunity to improve patient well-being by identifying and treating the underlying disorder.

Can convective therapies improve dialysis outcomes?

PURPOSE OF REVIEW

Convective treatments are characterized by enhanced removal of middle and large molecular weight solutes, important in the genesis of many complications of hemodialysis, compared with conventional low-flux hemodialysis. The availability of these techniques represented an intriguing innovation and a possible means to improve the still poor prognosis of hemodialysis patients. In this study we will critically review the most important published studies evaluating the impact of convective treatments on dialysis outcomes.

RECENT FINDINGS

The Hemodialysis (HEMO) study showed that greater urea removal nonsignificantly reduces the relative risk of mortality and that also high-flux hemodialysis was associated with a nonsignificant reduction, although a secondary analysis pointed to an advantage for high-flux membranes in subgroups of patients. More recently, the Membrane Permeability Outcome (MPO) study found that survival could be improved by use of high-flux membranes compared with low-flux dialysis in high-risk patients as identified by serum albumin < or =4 g/dl as well as in people with diabetes. In an observational study, hemodiafiltration with large reinfusion volume has been associated with a lower relative risk of mortality, compared with low-flux hemodialysis.

SUMMARY

The biologic plausibility of advantages of convective treatments and the results of the MPO and Dialysis Outcomes and Practice Patterns (DOPPS) studies are supporting rationales for the use of convective treatments to improve survival and delay long-term complications of hemodialysis patients.

Cytokine patterns and survival in haemodialysis patients

BACKGROUND

Increased pro-inflammatory cytokine levels are associated with decreased survival. We performed factor analyses to determine if pro-inflammatory and anti-inflammatory cytokines in haemodialysis (HD) patients load onto one or two discrete factors and assessed if patients with a specific pattern of high pro-inflammatory cytokines have decreased survival compared to patients with a high anti-inflammatory cytokine pattern.

METHODS

We evaluated 231 HD patients and analyzed them based on the three most common cytokine distribution patterns seen: a high pro-inflammatory group, a high anti-inflammatory group and all others. Survival and Cox regression analyses were performed.

RESULTS

Factor analyses of individual cytokines showed that they loaded onto a single factor. Sixty-five patients had a pro-inflammatory pattern of high IL-1, IL-6 and TNF-alpha levels and low anti-inflammatory parameters, including IL-2, IL-4, IL-5, IL-12, CH50 and T-cell number. The next most frequent cytokine pattern was found in 20 patients with high levels of anti-inflammatory parameters. The patients with high pro-inflammatory cytokines had decreased survival compared to patients without a characteristic cytokine pattern.

CONCLUSIONS

Further research is needed to better define the underlying causes of increased inflammation among end-stage renal disease patients and to apply anti-inflammatory therapies that may mitigate adverse effects on patient outcomes.

Determinants of left ventricular mass and hypertrophy in hemodialysis patients assessed by cardiac magnetic resonance imaging

BACKGROUND AND OBJECTIVES

Left ventricular hypertrophy (LVH) is an independent risk factor for premature cardiovascular death in hemodialysis (HD) patients and one of the three forms of uremic cardiomyopathy. Cardiovascular magnetic resonance (CMR) is a volume-independent technique to assess cardiac structure. We used CMR to assess the determinants of left ventricular mass (LVM) and LVH in HD patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A total of 246 HD patients (63.8% male; mean age 51.5 +/- 12.1 yr) underwent CMR on a postdialysis day. LVM was measured from a stack of cine loops and indexed for body surface area (LVM index [LVMI]). Demographic, past biochemical, hematologic, and dialysis data were collected by patient record review. Results up to 180 d before CMR were collected. LVH was defined as LVMI >84.1 g/m(2) (male) or >76.4 g/m(2) (female).

RESULTS

A total of 157 (63.8%) patients had LVH. LVH was more common in patients with higher predialysis systolic BP, predialysis pulse pressure, and calcium-phosphate product (Ca X PO4). Furthermore, LVH was significantly associated with higher end-diastolic and systolic volumes and lower ejection fraction. There were positive correlations with LVMI and end-diastolic and systolic volumes. There were weak positive correlations among LVMI, mean volume of ultrafiltration, and Ca X PO4. Using multivariate linear and logistic regression (entering one BP and cardiac variable), the independent predictors of LVMI and LVH were end-diastolic volume, predialysis systolic BP, and Ca X PO4.

CONCLUSIONS

The principal determinants of LVM and LVH in HD patients are end-diastolic LV volume, predialysis BP, and Ca X PO4.

On Small Solute Clearance and Patient Outcomes: Evidential Practice or Observational Trepidation?

Recent guidelines on peritoneal dialysis adequacy set a minimum target for small solute clearance at Kt/V urea 1.70. While evidence from both observational studies and randomized controlled trials (RCTs) supports such a minimum target, there continues to be debate over what role small solute clearance plays in determining patient outcome. Current ANZDATA Registry results from Australia and New Zealand add fuel to this debate by demonstrating a significant nonlinear U-shaped relationship between peritoneal small solute clearance and patient survival. The ANZDATA results indicate that patients with too low or too high peritoneal Kt/V urea may be at significant risk of death compared to those with a peritoneal Kt/V urea between 1.70 and 2.00. As these results are somewhat at odds with results from published RCTs, we will examine the level of evidence from the observational setting that is the ANZDATA Registry and contrast it against the level of evidence from RCTs, particularly the ADEMEX trial. New results from the ADEMEX study are presented as a possible explanation for the paradoxical U-shaped results seen in the ANZDATA study.

Depressive mood in pre-dialytic chronic kidney disease: Statistical parametric mapping analysis of Tc-99m ECD brain SPECT

The purpose of this study was to investigate depression-related regions in pre-dialytic patients with chronic kidney disease (CKD) patients. Participants comprised 33 patients with stage 4 and 5 CKD (age, 55 [42-63]) and 32 healthy volunteers (age, 53.5 [49.5-57]). Depressed mood was assessed in the patients, and both groups underwent Tc-99m-labeled ethylcysteinate dimer (Tc-99m ECD) single photon emission computed tomograpy (SPECT). Statistical parametric mapping identified 18 areas of hypoperfusion in the patients in comparison with the normal controls. The largest clusters were areas including left precentral gyrus, right superior and middle temporal gyrus, both cerebellar posterior lobes, both inferior frontal gyrus, right superior and middle frontal gyrus, right cuneus, right inferior parietal lobule, and right putamen. However, there were no specific hypoperfusion areas in CKD patients with depression compared with CKD patients without depression. Interestingly, several hypoperfusion areas in CKD patients (inferior frontal gyrus [BA46], superior temporal gyrus [BA42], anterior cingulate gyrus [BA24]) were concordant with hypoperfusion areas found in patients with major depression who were free of kidney disease. In conclusion, this study did not demonstrate specific depression-related cerebral hypoperfusion areas. However, the cerebral blood flow pattern in CKD patients was similar to that of patients with major depression in some areas. Although further investigations are needed in the future, we suggest that the causes of the higher prevalence of depression in CKD might be associated with this finding.

Body composition in home haemodialysis versus conventional haemodialysis: a cross-sectional, matched, comparative study

BACKGROUND

Nutritional status predicts outcome in dialysis populations. Increased dialysis time and/or frequency reportedly improves nutritional status. We examined the impact of more intensive dialysis on body composition.

METHODS

A cross-sectional, matched study comparing home haemodialysis (HHD) patients (>15 h/week, n = 28) and conventional haemodialysis (CHD) patients (<15 h/ week, n = 28), matched for age, sex, length of time on dialysis and diabetes, was performed. We measured total body protein (TBP) by in vivo neutron activation, total body fat (TBF) and skeletal muscle mass (SKMM) by dual-energy x-ray absorptiometry (DEXA) and biochemical and inflammatory parameters. Visceral (VFA) and subcutaneous fat areas (SFA) were determined from computed tomography.

RESULTS

There was no significant difference in TBP (10.2 +/- 1.9 kg CHD versus 10.8 +/- 1.8 kg HHD, P = 0.18) or SKMM (25.6 +/- 5.6 kg CHD versus 26.2 +/- 4.2 kg HHD). TBF was not different (27.7 +/- 10.7 kg CHD versus 27.8 +/- 16.0 kg HHD), although the HHD group had greater VFA (182.0 +/- 105.6 cm(2) versus 173.8 +/- 90.1 cm(2)) and lower SFA (306.7 +/- 176.4 cm(2) versus 309.7 +/- 138.1 cm(2)), the difference was not statistically significant. Albumin concentrations were significantly increased in the HHD group (37.5 +/- 3.56 g/L versus 35.18 +/- 4.11 g/L, P = 0.03), whilst phosphate concentrations (1.57 +/- 0.41 mmol/LHHD versus 1.92 +/- 0.62 mmol/ LCHD, P = 0.02) and inflammatory parameters were lower. There was a positive relationship between hours of dialysis and TBP (beta = 0.08; P = 0.03).

CONCLUSION

Surrogate nutritional markers and inflammatory parameters improved with more intensive dialysis, but this was not reflected by improved body composition. Further prospective studies are required to confirm whether more intensive dialysis affects body composition, and whether this impacts on metabolic risk and clinical outcome.

What's next after fistula first: is an arteriovenous graft or central venous catheter preferable when an arteriovenous fistula is not possible?

Findings from observational studies have established that the arteriovenous fistula (AVF) is the preferred form of vascular access for chronic hemodialysis. Unfortunately, in a subset of patients with end-stage renal disease, an AVF cannot be placed or fails to mature. In these patients an alternate form of vascular access, either an arteriovenous graft (AVG) or central venous catheter (CVC) must be selected. In this review we discuss the findings and limitations of studies examining the effect of access type (AVG or CVC) on clinical endpoints including mortality, quality of life, occurrence of infections, as well as the impact of the different access types on resource requirements. Specifically, we examine whether findings from previous studies are valid and applicable to patients for whom an AVF is not possible, and outline the need for future randomized clinical trials addressing this question.

Considerations in the statistical analysis of hemodialysis patient survival

The association of hemodialysis dosage with patient survival is controversial. Here, we tested the hypothesis that methods for survival analysis may influence conclusions regarding dialysis dosage and mortality. We analyzed all-cause mortality by proportional hazards and accelerated failure time regression models in a cohort of incident hemodialysis patients who were followed for 9 yr. Both models identified age, race, heart failure, physical functioning, and comorbidity scores as important predictors of patient survival. Using proportional hazards, there was no statistically significant association between mortality and Kt/V (hazard ratio 0.72; 95% confidence interval 0.45 to 1.14). In contrast, using accelerated failure time models, each 0.1-U increment of Kt/V improved adjusted median patient survival by 3.50% (95% confidence interval 0.20 to 7.08%). Proportional hazard models also yielded less accurate estimates for median survival. These findings are consistent with an additive damage model for the survival of patients who are on hemodialysis. In this conceptual model, the assumptions of the proportional hazard model are violated, leading to underestimation of the importance of dialysis dosage. These results suggest that future studies of dialysis adequacy should consider this additive damage model when selecting methods for survival analysis. Accelerated failure time models may be useful adjuncts to the Cox model when studying outcomes of dialysis patients.

Anemia management and association of race with mortality and hospitalization in a large not-for-profit dialysis organization

BACKGROUND

The optimal hemoglobin target and possible toxicity of epoetin therapy in hemodialysis patients are controversial. Previous studies suggest that African American patients use higher doses of epoetin and have better survival compared with white hemodialysis patients.

STUDY DESIGN

Retrospective longitudinal cohort.

SETTING & PARTICIPANTS

Epoetin-exposed incident hemodialysis patients (N = 12,733; African Americans, n = 4,801; white, n = 7,386) treated in Dialysis Clinic Inc facilities during 2000 to 2006.

PREDICTORS

Hemoglobin, epoetin, iron.

OUTCOMES

Mortality, hospitalization.

MEASUREMENTS

Proportional hazards models with time-varying covariates.

RESULTS

Hemoglobin concentrations less than 10 g/dL in whites and less than 11 g/dL in African Americans were associated with increased mortality and hospitalization versus the referent hemoglobin level of 11 to 11.9 g/dL. Hemoglobin levels of 13 g/dL or greater in whites were associated with decreased noncardiovascular mortality. Six-month cumulative epoetin doses of 20,000 U/wk or greater were associated with increased mortality and hospitalization versus the referent group (8,000 to 12,499 U/wk). Epoetin doses less than 8,000 U/wk were associated with decreased risk. Higher epoetin doses were associated with increased mortality at hemoglobin concentrations of 10 to 12.9 g/dL and with increased hospitalization at all hemoglobin concentrations of 10 g/dL or greater. Higher epoetin doses were associated with increased mortality and hospitalization within each tertile of serum albumin concentration. These patterns did not differ by race.

LIMITATIONS

Treatment-by-indication bias and unidentified confounders cannot be excluded. Small sample sizes in the highest and lowest hemoglobin strata decrease statistical power.

CONCLUSIONS

Relationships between hemoglobin concentration and mortality differed between African Americans and whites. Additionally, the relationship of lower mortality with greater achieved hemoglobin concentration seen in white patients was observed for all-cause, but not cardiovascular, mortality. A higher cumulative epoetin dose was associated with worse outcomes, even in patients with albumin levels greater than 4 g/dL. There were no statistically significant interactions between race and epoetin dose. Further studies are needed to confirm and to define the mechanism of these findings.

Management of Patients after Renal Graft Loss: An Open Question for Nephrologists

Patients undergoing renal graft failure and returning to dialysis are often regarded to like facing for the first time a substitutive treatment, without considering the technical complications, the economical impact, and the psychological implications. This review attempt, to give answers to various questions, concerning the management of vascular access, the immunosuppressive therapy, the transplantectomy, the emotional and neuropsychic aspects, and the quality of life of graft-failed patients.

Effects of protein supplementation in chronic hemodialysis and peritoneal dialysis patients

OBJECTIVE

We evaluated the impact of oral protein supplementation given during hemodialysis and peritoneal dialysis on nutritional status, number of hospitalizations, and length of stay.

DESIGN

We used a randomized crossover design in which serum albumin, normalized protein catabolic rate (nPCR), total hospitalizations, and length of stay were compared in patients who received protein supplements with those who did not. The study was conducted for 1 year (November 2005 to October 2006).

SETTING

This study was conducted at an outpatient dialysis facility.

SUBJECTS

Forty-nine patients were treated with hemodialysis or peritoneal dialysis for at least 3 months.

RESULTS

The nPCR significantly increased by month 4 of treatment from a baseline of 1.05 to 1.16 (P = .007). The control group had a significant decline in nPCR during the first 6 months, from 1.11 to 0.98 (P = .038). Improvement was evident in albumin by month 3, from 3.49 to 3.52 (P = .035), but this was not sustained. In the second 6 months, the control group had a significant drop, from 3.35 to 3.19 (P = .014), and the difference between the protein-supplementation and control groups was significant during the second 6 months (P = .037). The nPCR also dropped significantly (P = .024) for the control group in the second 6 months. When protein supplementation ended, weight dropped significantly for those with a body mass index of <20. Trends toward a reduction in hospitalization admissions and hospital days were seen in both crossover treatment groups.

CONCLUSIONS

In-center supplementation of protein generally improves serum markers of nutrition overall, and when it is discontinued, these markers decline. Larger studies are needed to confirm the trends that we observed regarding nutritional markers and reductions in hospitalizations and hospitalization days.

Association between repeat hospitalization and early intervention in dialysis patients following hospital discharge

Dialysis patients have a greater number of hospitalization events compared to patients without renal failure. Here we studied the relationship between different post-discharge interventions and repeat hospitalization in over 126,000 prevalent hemodialysis patients to explore outpatient strategies that minimize the risk of repeat hospitalization. The primary outcome was repeat hospitalization within 30 days of discharge. Compared to pre-hospitalization values, the levels of hemoglobin, albumin, phosphorus, calcium, and parathyroid hormone and weight were significantly decreased after hospitalization. Using covariate-adjusted models, those patients whose hemoglobin was monitored within the first 7 days after discharge, followed by modification of their erythropoietin dose had a significantly reduced risk for repeat-hospitalization when compared to the patients whose hemoglobin was not checked, nor was the dose of erythropoietin changed. Similarly, administration of vitamin D within the 7 days following discharge was significantly associated with reduced repeat hospitalization when compared to patients on no vitamin D. Therefore, it appears that immediate re-evaluation of anemia management orders and resumption of vitamin D soon after discharge may be an effective way to reduce repeat hospitalization.

Effects of peridialytic oral supplements on nutritional status and quality of life in chronic hemodialysis patients

OBJECTIVE

Our objective was to determine the effects of peridialytic oral supplements on nutritional markers and quality of life (QOL) in patients receiving maintenance hemodialysis.

DESIGN

This trial was open, prospective, nonrandomized, and comparative.

SETTING

This study was performed at an outpatient hemodialysis unit in a teaching hospital.

PATIENTS

This study included 88 adults with chronic kidney disease at stage 5.

INTERVENTION

This study involved directly observed nutrition therapy with >or=1 can of enteral nutrition (Nepro) with each hemodialysis session thrice weekly for 3 months, or standard care.

MAIN OUTCOME MEASURE

Changes in biochemical markers of nutritional status and QOL, as measured by the Kidney Disease Quality of Life-Short Form, were determined.

RESULTS

Peridialytic oral nutrition resulted in a significant difference between the nutrition and comparison groups in serum albumin change over time (P = .03; repeated-measures analysis of variance with covariates). Mean (+/-SD) serum albumin concentration did not differ between baseline and month 3 in the nutrition group (3.68 +/- 0.33 g/dL vs. 3.75 +/- 0.40 g/dL; P = .12), but in the comparison group, serum albumin levels declined significantly (3.93 +/- 0.34 g/dL at baseline versus 3.81 +/- 0.37 g/dL at month 3; P = .04). The "role-physical" domain score of the Kidney Disease Quality of Life-Short Form significantly changed over time in the nutrition group versus the comparison group (P = .02; repeated-measures analysis of variance with covariates). Nepro was well-tolerated, and greater than 80% of the prescribed therapy was consumed.

CONCLUSION

Oral nutrition, as part of structured, directly observed peridialytic therapy in chronic hemodialysis patients, was well-accepted, and resulted in the maintenance of serum albumin levels and QOL with respect to impact of physical health on daily activities. These findings need to be confirmed in a randomized, controlled trial.

Plasma gelsolin and circulating actin correlate with hemodialysis mortality

Plasma gelsolin (pGSN) binds actin and bioactive mediators to localize inflammation. Low pGSN correlates with adverse outcomes in acute injury, whereas administration of recombinant pGSN reduces mortality in experimental sepsis. We found that mean pGSN levels of 150 patients randomly selected from 10,044 starting chronic hemodialysis were 140 +/- 42 mg/L, 30 to 50% lower than levels reported for healthy individuals. In a larger sample, we performed a case-control analysis to evaluate the relationship of pGSN and circulating actin with mortality; pGSN levels were significantly lower in 114 patients who died within 1 yr of dialysis initiation than in 109 survivors (117 +/- 38 mg/L versus 147 +/- 42 mg/L, P < 0.001). pGSN levels had a graded, inverse relationship with 1-yr mortality, such that patients with pGSN < 130 mg/L experienced a > 3-fold risk for mortality compared with those with pGSN > or = 150 mg/L. The 69% of patients with detectable circulating actin had lower pGSN levels than those without (127 +/- 45 mg/L versus 141 +/- 36 mg/L, P = 0.026). Compared with patients who had elevated pGSN and no detectable actin, those with low pGSN levels and detectable actin had markedly increased mortality (odds ratio 9.8, 95% confidence interval 2.9 to 33.5). Worsening renal function correlated with pGSN decline in 53 subjects with CKD not on dialysis. In summary, low pGSN and detectable circulating actin identify chronic hemodialysis patients at highest risk for 1-yr mortality.

Anticoagulant and antiplatelet usage associates with mortality among hemodialysis patients

Many prescribe anticoagulants and antiplatelet medications to prevent thromboembolic events and access thrombosis in dialysis patients despite limited evidence of their efficacy in this population. This retrospective cohort study examined whether use of warfarin, clopidogrel, and/or aspirin affected survival in 41,425 incident hemodialysis patients during 5 yr of follow-up. The prescription frequencies for warfarin, clopidogrel, and aspirin were 8.3, 10.0, and 30.4%, respectively, during the first 90 d of initiating chronic hemodialysis. Compared with the 24,740 patients receiving none of these medications, Cox proportional hazards analysis suggested that exposure to these medications was associated with increased risk for mortality (warfarin hazard ratio [HR] 1.27 [95% confidence interval (CI) 1.18 to 1.37]; clopidogrel HR 1.24 [95% CI 1.13 to 1.35]; and aspirin HR 1.06 [95% CI 1.01 to 1.11]). The increased mortality associated with warfarin or clopidogrel use remained in stratified analyses. A covariate- and propensity-adjusted time-varying analysis, which accounted for longitudinal changes in prescription, produced similar results. In addition, matching for treatment facility and attending physician revealed similar associations between prescription and mortality. We conclude that warfarin, aspirin, or clopidogrel prescription is associated with higher mortality among hemodialysis patients. Given the possibility of confounding by indication, randomized trials are needed to determine definitively the risk and benefit of these medications.

Nutritional status evaluation and survival in haemodialysis patients in one centre from Romania

BACKGROUND

Protein-energy wasting is a common complication and an important predictive factor for mortality in chronic dialysis patients. Therefore, nutritional status needs to be regularly assessed in these patients, by using several methods, and, if malnutrition is present, its possible causes should be thoroughly searched for and properly treated.

MATERIAL AND METHODS

In 149 prevalent haemodialysis patients (82 men, mean age 53.9 +/- 13.7 years), we evaluated the nutritional status by anthropometrics [post-dialysis height (H), body weight (BW), body mass index (BMI), mid-arm circumference (MAC), tricipital skin-fold thickness (TST), mid-arm muscle circumference (MAMC), corrected mid-arm muscle area (cMAMA) and three-category subjective global assessment score (SGA)], biochemical tests [protein equivalent of nitrogen appearance (nPNA), and pre-dialysis serum albumin, creatinine, total cholesterol, bicarbonate and haemoglobin (Hb) levels] and bioelectrical impedance analysis (BIA) to estimate body composition [percent body fat (%BF), fat-free mass (%FFM), body cell mass (%BCM), extracellular mass (%ECM) and the phase angle (PhA)].

RESULTS

Age was found to be positively correlated with BMI (P = 0.001), and inversely correlated with %BCM (P = 0.013). Patients with A-category SGA were significantly younger (50.1 versus 63.7 years) than those with B-category SGA. Patients with diabetes had lower %BCM (32.9 versus 35.9%; P = 0.035) and PhA (5.5 versus 6.9 degrees ; P = 0.0007) than those without diabetes. The presence of heart failure was associated with significantly reduced nPNA (1.17 versus 1.34 g/kg day; P = 0.014), MAMC (22.0 versus 23.6 cm(2); P = 0.041), %BCM (33.0 versus 36.1; P = 0.021), PhA (5.8 versus 7.0 degrees ; P = 0.031), serum albumin (39.7 versus 42.4 g/l; P = 0.013) and serum creatinine (8.1 versus 9.4 mg/dl; P = 0.010), and with a higher percent of B-category SGA (47.8% versus 22.6%; P = 0.019). Eleven deaths (7.4%) occurred during the follow-up period. Among general factors, age >or= 55, the presence of diabetes, and dialysis vintage <2 years were associated with significantly reduced survival. Among nutritional factors, B-category SGA, nPNA <1.2 g/kg day, %BF <15% and PhA <6 degrees significantly predicted mortality in both Kaplan-Meier and Cox analyses. The most important risk factor appeared to be nPNA; for every 0.1 g/kg day increase in nPNA, death risk decreased by 15%.

CONCLUSIONS

In our haemodialysis patients, advancing age, diabetes and heart failure were associated with worse nutritional status, as estimated by anthropometry, biochemical markers and BIA. Age >or=55 years, the presence of diabetes, nPNA <1.2 g/kg day, lower SGA score, %BF <15% and PhA <6 degrees were associated with significantly increased death risk.

Greater first-year survival on hemodialysis in facilities in which patients are provided earlier and more frequent pre-nephrology visits

BACKGROUND AND OBJECTIVES

The aim of this study was to evaluate the relation between pre-nephrology visit (PNV) and 1-yr patient survival after hemodialysis (HD) induction.

DESIGN, SETTING PARTICIPANTS, & MEASUREMENTS

Data were analyzed from 8500 incident HD patients (on HD <or=30 d) in the Dialysis Outcomes and Practice Patterns Study (DOPPS) phases I and II. A visit to a nephrologist at least 1 mo before starting HD was regarded as PNV. Cox regression was used to estimate the adjusted hazard ratio (AHR) for mortality in the first year of HD in both patient- and facility-level analyses. All models were adjusted for age, sex, race, socioeconomic factors, cause of ESRD, 14 comorbid conditions, hemoglobin, serum albumin, and serum creatinine; accounted for facility clustering effects; and were stratified by country.

RESULTS

In patient-level analysis, PNV was associated with significantly lower risk for death (AHR 0.57; P < 0.0001). Facility-level analysis also showed a significant lower risk for death in facilities with greater prevalence of PNV in both continuous models (AHR 0.92 per 10% greater facility mean %PNV; P < 0.0004) and in categorical models (AHR 0.71 for facilities with >90% of patients receiving PNV [first quartile] compared with facilities with <71% of patients receiving PNV [fourth quartile]; P = 0.001).

CONCLUSIONS

These results provide not only patient-level but also facility practice evidence that PNV is related to improved patient survival during the first year after initiation of HD, indicating the possible mortality benefits with more increased attention to PNV.

Treatment time, chronic inflammation, and hemodynamic stability: the overlooked parameters in hemodialysis quantification

Decades after the introduction of chronic maintenance hemodialysis, the optimal means of quantifying dialysis dose remains controversial. Differences of opinion in the international dialysis community lead to substantial diversity in everyday clinical practice. Several studies suggest that the well-recognized international mortality differences in hemodialysis populations may result from these divergent approaches to dialysis care. One of the main areas of divergence is the different degree of reliance on dialysis clearance when prescribing dialysis. The "clearance approach" implies that treatment quality is primarily dependent on efficient removal of uremic toxins as estimated by dialytic urea clearance. Urea can be rapidly removed by high efficiency dialysis in a relatively short time. The main alternative to this strategy is the "time approach" based on the recognition that longer or more frequent dialysis provides benefits beyond increasing urea removal. Some of the putative benefits are more effective volume and blood pressure control, better maintenance of hemodynamic stability because of slower ultrafiltration and removal of uremic toxins that do not behave like urea. Recently, chronic inflammation has been proposed to be an important predictor of outcome in dialysis patients. Inflammatory markers are commonly elevated in chronic renal failure and levels of these seem to correlate with malnutrition, maintenance of residual renal function, and volume control. The relationships between dialysis clearance, treatment time, chronic inflammation, volume control, and hemodynamic stability are explored in this review. We propose that a better understanding of these complex relationships may provide opportunities for improving outcomes of maintenance hemodialysis patients.

The importance of iron in long-term survival of maintenance hemodialysis patients treated with epoetin-alfa and intravenous iron: analysis of 9.5 years of prospectively collected data

Background

In patients treated by maintenance hemodialysis the relationship to survival of hemoglobin level and administered epoetin-alfa and intravenous iron is controversial. The study aim was to determine effects on patient survival of administered epoetin-alfa and intravenous iron, and of hemoglobin and variables related to iron status.

Methods

The patients were 1774 treated by maintenance hemodialysis in 3 dialysis units in New York, NY from January 1998 to June, 2007. A patient-centered, coded, electronic patient record used in patient care enabled retrospective analysis of data collected prospectively. For survival analysis, patients were censored when transplanted, transferred to hemodialysis at home or elsewhere, peritoneal dialysis. Univariate Kaplan-Meier analysis was followed by multivariate analysis with Cox's regression, using as variables age, race, gender, major co-morbid conditions, epoetin-alfa and intravenous iron administered, and 15 laboratory tests.

Results

Median age was 59 years, epoetin-alfa (interquartile range) 18,162 (12,099, 27,741) units/week, intravenous iron 301 (202, 455) mg/month, survival 789 (354, 1489) days. Median hemoglobin was 116 (110, 120)g/L, transferrin saturation 29.7 (24.9, 35.1)%, serum ferritin 526 (247, 833) μg/L, serum albumin 39.0 (36.3, 41.5) g/L. Survival was better the higher the hemoglobin, best with > 120 g/L. Epoetin-alfa effect on survival was weak but had statistically significant interaction with intravenous iron. For intravenous iron, survival was best with 1–202 mg/month, slightly worse with 202–455 mg/month; it was worst with no intravenous iron, only slightly better with > 455 mg/month. Survival was worst with transferrin saturation ≤ 16%, serum ferritin ≤ 100 μg/L, best with transferrin saturation > 25%, serum ferritin > 600 μg/L The effects of each of hemoglobin, intravenous iron, transferrin saturation, and serum ferritin on survival were independently significant and not mediated by other predictors in the model.

Conclusion

Long term survival of maintenance hemodialysis patients was favorably affected by a relatively high hemoglobin level, by moderate intravenous iron administration, and by indicators of iron sufficiency. It was unfavorably influenced by a low hemoglobin level, and by indicators of iron deficiency.

Continuous veno-venous hemofiltration with regional citrate anticoagulation: a four-year single-center experience

BACKGROUND

Hemofiltration protocols using a citrate-buffered replacement solution offer the advantage of regional anticoagulation and a buffer effect. The role played by such fluids in clinical practice is not yet well established. The risk of electrolytic disorders, acid-base imbalance, or citrate accumulation should be clarified. We report on a renal therapy protocol based on a citrate isonatremic replacement solution.

METHOD

We considered all patients needing renal replacement therapy admitted to our cardiovascular intensive care unit between January 2003 and June 2007. A citrate-buffered fluid was delivered in predilution mode to a post-filter ionized calcium target < or = 0.25 mmol/L. Extracorporeal blood flow was set at a constant of 140+/-10 ml/min. Blood calcemia was maintained by a 5% calcium-chloride solution infused into the patient. We recorded the patients' acid-base variables, ionized calcium, daily electrolytes, albumin, urea and filter life-span.

RESULTS

We observed 101 consecutive patients out of 2,523; incidence 4%, overall mortality was 57% at ICU discharge. Mean replacement rate was 2,554+/-475 ml/h corresponding to 34+/-5 ml/kg/h. Mean patient ionized calcium level was 1.07+/-0.04 mmo/L, maintained by 13+/-2 ml/h of infused calcium-chloride. All other electrolytes remained in the normal range. The Stewart biophysical approach confirmed a strong anion gap of 3.1+/- 3 meq/L. Acid-base balance showed a buffer effect. Mean filter life-span was 52+/-11 h.

CONCLUSION

Renal replacement therapy based on citrate-buffered fluid may be useful in clinical practice. This methodology presented an adequate metabolic control and allowed regional anticoagulation. A sufficient calcium supply was mandatory to avoid hypocalcemia. The small strong ion gap suggested a modest citrate accumulation.

Quantitation of Markers of Protein Damage by Glycation, Oxidation, and Nitration in Peritoneal Dialysis

Proteolysis products of proteins damaged by glycation, oxidation, and nitration—glycated, oxidized, and nitrated amino acids (glycation, oxidation, and nitration free adducts)—are waste products normally excreted in urine and cleared in peritoneal dialysate. Glucose degradation products in peritoneal dialysis (PD) fluids may increase protein damage, giving rise to increased protein glycation, oxidation, and nitration adduct residues of proteins and increased flux of glycation, oxidation, and nitration free adducts. Increased protein damage has been linked to mortality in end-stage renal disease. Reliable quantitation of markers for adducts of protein glycation, oxidation, and nitration is required for mechanistic studies and for morbidity and mortality risk analysis in PD patients. We review the available analytical techniques for such quantitation. Stable isotopic dilution analysis with tandem mass spectrometry is the “gold standard.” This method needs to be applied further in the study of PD and to validate other techniques so that the effect of PD on the metabolism and clearance of damaged proteins and related products can be quantified, and so that best-practice fluid management can be established to minimize cardiovascular risk.

Surviving calciphylaxis

Calciphylaxis is a rare disorder with high mortality, which commonly occurs, but not limited to, patients with end-stage renal disease. We present a successful case in which a patient survived this serious disorder of vasculopathy, highlighting the physical and emotional morbidities associated with this condition and alerting physicians of the key elements in its management. Further understanding of calciphylaxis may advance our knowledge in endotheliopathy and vascular ossification.

Nutritional status and the role of diabetes mellitus in hemodialysis patients

This study was aimed to investigate the nutritional status and the role of diabetes mellitus in hemodialysis (HD) patients. Anthropometric, biochemical, and dietary assessments for HD 110 patients (46 males and 64 females) were conducted. Mean body mass index (BMI) was 22.1 kg/m(2) and prevalence of underweight (BMI<18.5 kg/m(2)) was 12%. The hypoalbuminemia (<3.5 g/dl) was found in 15.5% of the subject, and hypocholesterolemia (<150 mg/dl) in 46.4%. About half (50.9%) patients had anemia (hemoglobin: <11.0 g/dL). High prevalence of hyperphosphatemia (66.4%) and hyperkalemia (43.5%) was also observed. More than 60 percent of subjects were below the recommended intake levels of energy (30-35 kcal/kg IBW) and protein (1.2 g/kg IBW). The proportions of subjects taking less than estimated average requirements for calcium, vitamin B(1), vitamin B(2), vitamin C, and folate were more than 50%, whereas, about 20% of the subjects were above the recommended intake of phosphorus and potassium. Diabetes mellitus was the main cause of ESRD (45.5%). The diabetic ESRD patients showed higher BMI and less HD adequacy than nondiabetic patients. Diabetic patients also showed lower HDL-cholesterol levels. Diabetic ESRD patients had less energy from fat and a greater percentage of calories from carbohydrates. In conclusion, active nutrition monitoring is needed to improve the nutritional status of HD patients. A follow-up study is needed to document a causal relation between diabetes and its impact on morbidity and mortality in ESRD patients.

Effect of membrane permeability on survival of hemodialysis patients

The effect of high-flux hemodialysis membranes on patient survival has not been unequivocally determined. In this prospective, randomized clinical trial, we enrolled 738 incident hemodialysis patients, stratified them by serum albumin < or = 4 and >4 g/dl, and assigned them to either low-flux or high-flux membranes. We followed patients for 3 to 7.5 yr. Kaplan-Meier survival analysis showed no significant difference between high-flux and low-flux membranes, and a Cox proportional hazards model concurred. Patients with serum albumin < or = 4 g/dl had significantly higher survival rates in the high-flux group compared with the low-flux group (P = 0.032). In addition, a secondary analysis revealed that high-flux membranes may significantly improve survival of patients with diabetes. Among those with serum albumin < or = 4 g/dl, slightly different effects among patients with and without diabetes suggested a potential interaction between diabetes status and low serum albumin in the reduction of risk conferred by high-flux membranes. In summary, we did not detect a significant survival benefit with either high-flux or low-flux membranes in the population overall, but the use of high-flux membranes conferred a significant survival benefit among patients with serum albumin < or = 4 g/dl. The apparent survival benefit among patients who have diabetes and are treated with high-flux membranes requires confirmation given the post hoc nature of our analysis.

Associates of mortality and hospitalization in hemodialysis: potentially actionable laboratory variables and vascular access

BACKGROUND

To determine the most significant potentially actionable clinical variables associated with mortality and hospitalization risk in hemodialysis (HD) patients.

STUDY DESIGN

Cohort study.

SETTING & PARTICIPANTS

Adult maintenance HD patients in the Fresenius Medical Care, North America database as of January 1, 2004, with baseline information from October 1, 2003, to December 31, 2003, comprising approximately 26% of the US HD population.

PREDICTORS

Case-mix (age, sex, race, diabetes, vintage, and body surface area), vascular access, and laboratory (albumin, equilibrated Kt/V, hemoglobin, calcium, phosphorus, creatinine, bicarbonate, biointact parathyroid hormone, transferrin saturation, and white blood cell count) variables.

OUTCOMES

1-year mortality and hospitalization risk from January 1 to December 31, 2004.

MEASUREMENTS

Cox proportional hazards models for death and hospitalization.

RESULTS

The cohort (N = 78,420) had a mean age of 61.4 +/- 15.0 years, 47% were women, 49% were white, 41% were black race (10% defined as "other"), and 52% had diabetes. The top 5 actionable variables were the same for mortality and hospitalization. Final case-mix plus laboratory-adjusted hazard ratios for these top 5 actionable variables indicate 177% increased risk of death and 67% increased risk of hospitalization per 1-g/dL decrease in albumin level, 39% and 45% greater risk with catheters compared with fistulas, 18% and 9% greater risk per 1-mg/dL greater phosphorus level, 11% and 9% lower risk per 1-g/dL greater hemoglobin level, and 5% and 2% greater risk per 0.1-unit decrease in equilibrated Kt/V, respectively (all P < 0.0001).

LIMITATIONS

Observational cross-sectional study with limited comorbidity adjustment (for diabetes).

CONCLUSION

The same variables are associated with both mortality and hospitalization in HD patients. The top 5 potentially actionable variables are readily identifiable, with albumin level and catheter use the most prominent, and all 5 are appropriate targets for improvement.

Associations of interleukin-6, C-reactive protein and serum amyloid A with mortality in haemodialysis patients

BACKGROUND

Individuals with end-stage renal disease (ESRD) manifest a chronic inflammatory state. Serum albumin, C-reactive protein (CRP), interleukin-6 (IL-6) and serum amyloid A (SAA) have been associated with mortality in ESRD, although reports vary as to whether they are true independent markers of mortality. We undertook a prospective study to determine whether these markers could predict mortality in ESRD.

METHODS

A cohort of individuals on haemodialysis was followed prospectively for a mean of 2.1 years. Albumin, CRP, IL-6 and SAA were drawn at enrollment. Association between mortality and serum markers was assessed using Cox proportional hazards regression. A trend analysis was undertaken to establish the functional form of the association between serum markers and outcome.

RESULTS

After multivariable adjustment, IL-6 was most strongly associated with mortality, followed closely by albumin (P = 0.0002 and P = 0.0005, respectively). CRP was marginally associated with mortality (P = 0.046), and SAA was not independently associated with mortality. In the final model adjusting for the effects of both IL-6 and albumin simultaneously, both markers remained associated with mortality (P = 0.003 and P = 0.011).

CONCLUSION

IL-6 had the strongest independent association with mortality, followed closely by albumin. CRP and SAA were not associated with mortality when measured at single time points. Increasing levels of IL-6 and decreasing levels of albumin were associated with increased mortality. IL-6 and albumin may be capturing different aspects of the inflammatory burden observed in haemodialysis patients.

Comparison of proposed alternative methods for rescaling dialysis dose: resting energy expenditure, high metabolic rate organ mass, liver size, and body surface area

A number of denominators for scaling the dose of dialysis have been proposed as alternatives to the urea distribution volume (V). These include resting energy expenditure (REE), mass of high metabolic rate organs (HMRO), visceral mass, and body surface area. Metabolic rate is an unlikely denominator as it varies enormously among humans with different levels of activity and correlates poorly with the glomerular filtration rate. Similarly, scaling based on HMRO may not be optimal, as many organs with high metabolic rates such as spleen, brain, and heart are unlikely to generate unusually large amounts of uremic toxins. Visceral mass, in particular the liver and gut, has potential merit as a denominator for scaling; liver size is related to protein intake and the liver, along with the gut, is known to be responsible for the generation of suspected uremic toxins. Surface area is time-honored as a scaling method for glomerular filtration rate and scales similarly to liver size. How currently recommended dialysis doses might be affected by these alternative rescaling methods was modeled by applying anthropometric equations to a large group of dialysis patients who participated in the HEMO study. The data suggested that rescaling to REE would not be much different from scaling to V. Scaling to HMRO mass would mandate substantially higher dialysis doses for smaller patients of either gender. Rescaling to liver mass would require substantially more dialysis for women compared with men at all levels of body size. Rescaling to body surface area would require more dialysis for smaller patients of either gender and also more dialysis for women of any size. Of these proposed alternative rescaling measures, body surface area may be the best, because it reflects gender-based scaling of liver size and thereby the rate of generation of uremic toxins.