Serum albumin concentration-related Health Care Financing Administration quality assurance criterion is method-dependent: revision is necessary

Performance evaluation of different albumin assays for the detection of analbuminemia

Analbuminemia is characterized by the near absence of albumin in the plasma. Different methods are available for measuring albumin levels, but they do not necessarily agree with one another. It is a concern that analbuminemic samples could be falsely characterized due to the incorrect estimation of albumin. The objective of the work was to evaluate the performance of different assays in detecting analbuminemia. Albumin knockout (Alb-/-) mouse plasma was used to test the suitability of different albumin assays for their ability to properly characterize extreme albumin deficiency. Bromocresol green (BCG), bromocresol purple (BCP), enzyme-linked immunosorbent assay (ELISA), liquid chromatography-tandem mass spectrometry (LC-MS/MS), and gel electrophoresis were tested. The LC-MS/MS assay exhibited broad coverage of the amino acid sequence of albumin and indicated 8,400-fold lower (P<0.0001) albumin expression in Alb-/- than wildtype (WT), demonstrating its suitability for identifying extreme albumin deficiency. ELISA estimated albumin at 1.5±0.1 g/dL in WT and was below the detection limit in all Alb-/- samples. Gel electrophoresis yielded consistent results with LC-MS/MS and ELISA. The BCG assay overestimated albumin with apparently appreciable albumin concentrations in Alb-/- mice, yet the assay still indicated a significant difference between genotypes (Alb-/-, 1.2±0.05 g/dL, WT, 3.7±0.1 g/dL, P<0.0001). BCP drastically overestimated albumin and could not successfully identify the known analbuminemic phenotype of Alb-/- mice. By using Alb-/- plasma as a reference material and LC-MS/MS as a reference method, ELISA and gel electrophoresis appear appropriate for identifying analbuminemia, while BCG and BCP are not suitable. It is concluded that dye-binding assays should be avoided when extreme hypoalbuminemia or analbuminemia is suspected.

Albumin determined by bromocresol green leads to erroneous results in routine evaluation of patients with chronic kidney disease

OBJECTIVES

Measurement of plasma albumin is pivotal for clinical decision-making in patients with chronic kidney disease (CKD). Routinely used methods as bromocresol green (BCG) and bromocresol purple (BCP) can suffer from aselectivity, but the impact of aselectivity on the accuracy of plasma albumin results of CKD-patients is still unknown. Therefore, we evaluated the performance of BCG-, BCP- and JCTLM-endorsed immunological methods in patients with various stages of CKD.

METHODS

We evaluated the performance of commonly used albumin methods in patients with CKD stages G1 through G5, the latter divided in two groups based on whether they received hemodialysis treatment. In total, 163 patient plasma samples were measured at 14 laboratories, on six different BCG and BCP-platforms, and four different immunological platforms. The results were compared with an ERM-DA-470k-corrected nephelometric assay. The implications on outcome is evaluated by the proportion of patient results <38 g/L for the diagnosis of protein energy wasting.

RESULTS

Albumin results determined with BCP- and immunological methods showed the best agreement with the target value (92.7 and 86.2 %, respectively vs. 66.7 % for BCG, namely due to overestimation). The relative agreement of each method with the target value was platform-dependent, with larger variability in agreement between platforms noted for BCG and immunological methods (3.2-4.6 and 2.6-5.3 %) as opposed to BCP (0.7-1.5 %). The stage of CKD had similar effects on the variability in agreement for the three method-groups (0.6-1.8 % vs. 0.7-1.5 % vs. 0.4-1.6 %). The differences between methods cause discrepancies in clinical decision-making, as structurally fewer patients were diagnosed with protein energy wasting upon using BCG-based albumin results.

CONCLUSIONS

Our study shows that BCP is fit for the intended use to measure plasma albumin levels in CKD patients from all stages, including patients on hemodialysis. In contrast, most BCG-based platforms falsely overestimate the plasma albumin concentration.

Surgical management of peritoneal metastasis: Opportunities for pharmaceutical research

Cytoreductive surgery (CRS) has emerged as a survival-extending treatment of peritoneal metastasis (PM); recent advances include using intraperitoneal chemotherapy (IPC) at normothermic or hyperthermic temperatures, or under pressure (CRS + IPC). Clinical CRS + IPC research has established its highly variable efficacy and suggested tumor size, tumor locations and presence of ascites as potential determinants. On the other hand, there is limited knowledge on the effects of pharmaceutical properties on treatment outcomes. The present study investigated the inter-subject variability of paclitaxel binding to proteins in patient ascites because some PM patients show accumulation of ascites and because activity and transport of highly protein-bound drugs such as paclitaxel are affected by protein binding. Ascites samples were collected from 26 patients and investigated for their protein contents using LC/MS/MS proteomics analysis and for the concentrations of total proteins and two major paclitaxel-binding proteins (human serum albumin or HSA and α-1-acid glycoprotein or AAG). The association constants of paclitaxel to HSA and AAG and the extent of protein binding of paclitaxel in patient ascites were studied using equilibrium dialysis. Proteomic analysis of four randomly selected samples revealed 288 proteins, >90% of which are also present in human plasma. Between 72% - 94% of paclitaxel was bound to proteins in patient ascites. The concentrations of HSA and AAG in ascites showed substantial inter-subject variations, ranging from 14.7 - 46.3 mg/mL and 0.13-2.56 mg/mL, respectively. The respective paclitaxel association constants to commercially available HSA and AAG were ∼ 3.5 and ∼ 120 mM. Calculation using these constants and the HSA and AAG concentrations in individual patient ascites indicated that these two proteins accounted for >85% of the total protein-binding of paclitaxel in ascites. The extensive drug binding to ascites proteins, by reducing the pharmacologically active free fraction, may lead to the diminished CRS efficacy in PM patients with ascites. Clinical advances in CRS + IPC have outpaced current knowledge of pharmaceutical properties in this setting. IPC, as a locally acting therapy, is subjected to processes different from those governing systemic treatments. This study, to our knowledge, is the first to illustrate the implications of drug properties in the CRS + IPC efficacy against PM. While drugs are now an integral part of PM patient management, there is limited pharmaceutical research in this treatment setting (e.g., effects of hyperthermia or pressure on drug transport or release from delivery systems, pharmacokinetics, pharmacodynamics). Hence, CRS + IPC of PM represents an area where additional pharmaceutical research can assist further development and optimization.

Measurement of serum albumin in nephrology: we need to improve

Serum albumin is a widely used biomarker in clinical nephrology. Serum albumin cut-off values are used to define disease, to predict outcome, and to guide patient care. The available commercial assays to measure serum albumin rely on different analytical principles, all with their own (analytical) specifications. This paper provides an overview of the different clinical applications of serum albumin measurements in nephrology, the (dis)advantages of the available assays and the estimates of the effects of the measurement uncertainty between different assays in clinical decision making. This paper concludes that harmonisation of serum albumin assay results are needed.

Nutritional Markers during Peritoneal Dialysis: Data from the 1998 Peritoneal Dialysis Core Indicators Study

Objective

This analysis explores the nutritional status of adult U.S. peritoneal dialysis (PD) patients.

Design

The Peritoneal Dialysis Core Indicators Study is a prospective cross-sectional prevalence survey describing the care provided to a random sample of adult U.S. PD patients.

Methods and Population

Prevalence data were collected from a national random sample of 1381 adult PD patients participating in the United States End Stage Renal Disease (ESRD) program.

Results

The median age of these patients was 55 years, 61% were Caucasian; the leading cause of ESRD was diabetes mellitus. Age, sex, size, peritoneal permeability, dialysis adequacy, and nutritional indices did not differ between patients on continuous ambulatory PD and patients on automated PD. The dialysis prescriptions employed achieved mean weekly Kt/V urea (wKt/V) and creatinine clearance (wCCr) values of 2.22 ± 0.57 and 67.8 ± 22.5 L/1.73 m2/week, respectively. The PD patients were large, with a mean body weight of 77 ± 21 kg and body mass index (BMI) of 27 ± 8.6 kg/m2. The mean serum albumin of these patients was 3.5 ± 0.51 g/dL, and 43% of values fell below the National Kidney Foundation Dialysis Outcomes Quality Initiative's desired range. The PD patients had a normalized protein equivalent of nitrogen appearance (nPNA) of 1.0 ± 0.57 g/kg/day, a normalized creatinine appearance rate (nCAR) of 17 ± 7.3 mg/kg/day, and an estimated lean body mass (%LBM) of 62% ± 18% of body weight. Serum albumin correlated positively with patient size, nCAR, and nPNA, but negatively with age, the presence of diabetes mellitus, female gender, erythropoietin dose, the creatinine dialysate-to-plasma ratio results of peritoneal equilibration testing, and the dialysis portion of the wCCr. The duration of ESRD experience correlated negatively with both serum albumin and patient size, although these relationships were complex.

Conclusion

Peritoneal dialysis patients generally have marginal serum albumin levels, a finding incongruent with alternative measures of nutritional status, such as weight, BMI, and creatinine generation. Serum albumin is reduced in patients with high peritoneal permeability ( i.e., rapid transporters) and, because these patients generally have higher than average wCCr values, serum albumin is inversely correlated with the dialysis component of the wCCr. The presumptive nutritional indicators (BMI, %LBM, nPNA, and serum albumin) provide disparate estimates, varying from 10% to 50% for the prevalence of nutritionally stressed PD patients.

Albumin and Amino Acid Levels as Markers of Adequacy in Continuous Ambulatory Peritoneal Dialysis

Similar to previous findings in HD patients, a markedly decreased serum albumin level has been found to be a strong predictor of morbidity and mortality in CAPD patients. However, a slight decrease in serum albumin levels (to about 30 g/L if measured with nephelometry or the bromcresol purple method) does not always seem to reflect impaired nutritional status or to be associated with an increased morbidity or mortality in CAPD patients. A low serum albumin level among CAPD patients is related to dialysate albumin loss, comorbidity, age, and a low dietary protein intake. The possible relation between the dialysis dose (as assessed by small solute clearances) and serum albumin levels among CAPD patients is much less established and needs further study, although serum albumin tends to increase in prospective studies of increased peritoneal dialysis dose.

Although the plasma levels of amino acids seem to be lower in CAPD patients compared to HD patients, this does not reflect the intracellular amino acid pattern in muscle which is less abnormal in CAPD patients, possibly because of the sustained hyperinsulinemia during CAPD, resulting in an in creased intracellular to extracellular gradient. It is at present not established to what extent the amino acid abnormalities are related to the dialysis dose.

Malnourished and hypoalbuminemic CAPD patients should be recommended to increase the protein intake, and if this is not effective, the dialysis dose should be increased. Furthermore, the use of amino acid-based peritoneal dialysis solutions is a promising new tool for the treatment of malnourished CAPD patients and may become an important component of CAPD therapy in the future. On the other hand, if the nutritional status deteriorates in spite of these efforts, the patient should be transferred to hemodialysis if possible.

The Effect of Serum Albumin at the Start of Continuous Ambulatory Peritoneal Dialysis Treatment on Patient Survival

Objective

To analyze the effect of serum albumin using immunoturbidimetry, demographic, biochemical, and kinetic factors on survival of continuous ambulatory peritoneal dialysis (CAPD) patients.

Design

A review of prospectively collected data in a 2-year follow-up study of peritoneal transport kinetics.

Setting

University medical center.

Participants

Sixty-one patients, evaluated within 3 months after the start of CAPD.

Main Outcome Measures

Covariables used in the survival analysis were plasma urea, and creatinine, albumin, hemoglobin, mass transfer area coefficient of creatinine, peritoneal albumin clearance, 4-hour peritoneal albumin loss, net ultrafiltration, age, blood pressure, body mass index, difference between actual and ideal body weight, and presence or absence of systemicdisease.

Results

Overall survival was 64% at 2 years. Median serum albumin was 30.9 g/L, range 18.1 -43.9 g/L. Patients with a serum albumin below the median had a lower survival rate than those higher than the median (2-year survival 49% vs 79%, p = 0.01). Using the Cox model, survival was related to systemic disease (p = 0.004), age (p = 0.02), hemoglobin (p = 0.03), and serum albumin (p = 0.1).

Conclusions

The results confirm the strength of serum albumin as predictor of survival. However, in this study serum albumin merely reflected the presence of a systemic disease, which was the most important risk factor for patient survival.

Evaluation of the Beckman Coulter DxC 700 AU chemistry analyzer

OBJECTIVES

We evaluated and defined the analytical performance of the Beckman Coulter DxC 700 AU analyzer compared to the Siemens Dimension Vista 500 analyzer.

DESIGN

and Methods: Performance characteristics included intra and inter-run precision, linearity/analytical measurement range, method correlation, and reference range verification. A total of 53 assays including 11 critical care, 19 general chemistries, 11 proteins, 10 urines, and 2 CSF analytes were tested. We also evaluated similarities and differences in assay methodologies between the 2 systems.

RESULTS

The DxC 700 AU demonstrated excellent precision, comparable analytical measurement ranges and strong method correlation with the Dimension Vista 500 for most serum/plasma assays. 95% of the intra-run and 95% of the inter-run precision QC levels showed <3.0%CV and <6.0%CV, respectively. None of the deviations were clinically significant. The AMRs for all analytes except 5 met the manufacturer's stated range. ALP, Lactate, U-glucose and CSF-glucose all recovered above the stated upper limit range, while prealbumin showed a smaller range. All analytes, except 14, showed slopes between 0.9 and 1.1 and/or biases <10%. Only ammonia, ferritin and lipase required significant reference range changes. The urine and CSF assays correlated very well with no adjustments in reference ranges required.

CONCLUSIONS

The analytical performance of the DxC 700 AU analyzer was acceptable with only a small number of analytes requiring significant reference range changes.

Laboratory performance in albumin and total protein measurement using a commutable specimen: results of a College of American Pathologists study

CONTEXT

Discrepant results for serum constituents were observed among peer groups in the College of American Pathologists Comprehensive Chemistry Survey.

OBJECTIVES

To assess the performance of serum albumin and total protein measurement procedures and to evaluate the commutability of the conventional survey specimens.

DESIGN

A fresh frozen, off-the-clot serum sample was included along with 4 conventional survey specimens. The fresh frozen, off-the-clot serum sample was prepared in a manner expected to confer commutability with native clinical samples.

RESULTS

For the fresh frozen, off-the-clot serum sample, the mean values for 17 peer-groups were -0.07 to 0.32 g/dL from the bromocresol green albumin designated comparison method, whereas 4 VITROS (Ortho Clinical Diagnostics, Rochester, New York) peer groups differed by -0.29 to -0.37 g/dL (15 of 21 differences [71%] had P < .001). For bromocresol purple albumin methods, the mean differences from the designated comparison method from 8 peer groups were 0.25 to 0.47 g/dL (all had P < .001). For total protein methods, 23 peer group mean values were -0.07 to 0.15 g/dL from the reference measurement procedure (12 of 24 [50%] had P < .001). The Beckman (Fullerton, California) Synchron LX20 had a bias of -0.30 g/dL (P <.001). The commutability of the conventional specimens was acceptable for 23 of 24 bromocresol green method-material combinations (96%) and 13 of 16 bromocresol purple albumin method-material combinations (81%). All (100%) of the 36 method-material combinations had acceptable commutability for total protein.

CONCLUSIONS

One (2.2%) of the instrument systems (Synchron) using bromocresol green and none (0%) of the instrument systems using bromocresol purple had satisfactory total-error performance for albumin measurement. Differences in results between bromocresol green and bromocresol purple methods precluded using common reference intervals for interpreting results for serum albumin. Eight of 9 instrument systems (86.5%) had satisfactory total-error performance for total protein measurement.

Hypoalbuminemia and early mortality after lung transplantation: a cohort study

Hypoalbuminemia predicts disability and mortality in patients with various illnesses and in the elderly. The association between serum albumin concentration at the time of listing for lung transplantation and the rate of death after lung transplantation is unknown. We examined 6808 adults who underwent lung transplantation in the United States between 2000 and 2008. We used Cox proportional hazard models and generalized additive models to examine multivariable-adjusted associations between serum albumin and the rate of death after transplantation. The median follow-up time was 2.7 years. Those with severe (0.5-2.9 g/dL) and mild hypoalbuminemia (3.0-3.6 g/dL) had posttransplant adjusted mortality rate ratios of 1.35 (95% CI: 1.12-1.62) and 1.15 (95% CI: 1.04-1.27), respectively. For each 0.5 g/dL decrease in serum albumin concentration the 1-year and overall mortality rate ratios were 1.48 (95% CI: 1.21-1.81) and 1.26 (95% CI: 1.11-1.43), respectively. The association between hypoalbuminemia and posttransplant mortality was strongest in recipients with cystic fibrosis and interstitial lung disease. Hypoalbuminemia is an independent risk factor for death after lung transplantation.

Discrepancies in Serum Albumin Measurements Vary by Dialysis Modality

BACKGROUND

Serum albumin level is an important prognostic marker in patients with chronic renal failure. However there are discrepancies in the methods of estimation of serum albumin. The objective of this study is to evaluate the magnitude of the discrepancy in the serum albumin levels as measured by Bromcresol Green (BCG) and Bromcresol Purple (BCP) dye methods in patients on hemodialysis (HD) and peritoneal dialysis (PD) and to ascertain the clinical determinants of the discrepancy (deltaSA = BCG-BCP; g/dL) in each of the modalities.

METHOD

We measured serum and plasma albumin levels by BCG and BCP methods in 19 adult HD patients and 18 adult PD patients treated in the dialysis units of the University of Colorado Health Sciences Center. Similar measurements were performed in 10 normal adult subjects. In all groups, paired blood samples were taken to estimate the albumin in both serum and plasma. Nephelometry (NM) was subsequently performed on the serum of 13 of the HD patients, 14 of the PD patients, and each of the 10 normal subjects.

RESULTS

We found that for both the dye methods serum and plasma albumin levels are almost identical in each of the three subject groups. In the normal subjects serum albumin estimated by BCP is in good agreement with NM values but BCG overestimates the albumin levels. In the PD group the discrepancy between the BCG and BCP (deltaSA) is statistically significant with the BCG averaging 0.59 +/- 0.12 g/dL more than the BCP. The BCG values are closer to those obtained by the "gold standard", NM. In the HD group the deltaSA is significantly (p < 0.001) less than in the PD group (0.34 +/- 0.11 g/dL). As for PD, BCG values are closer to NM values. Increasing age, female gender, and higher dialysis adequacy are associated with higher deltaSA in the HD but not in the PD group. Utilizing linear regression analysis we developed equations for each dialysis modality to convert albumin measurements from one method to the other.

CONCLUSION

We confirm that a discrepancy exists between the commonly used dye methods (BCG and BCP) for serum albumin estimation. This discrepancy is significantly lower in HD patients than in PD patients. Nephrologists should be aware of this discrepancy and appropriate corrections should be made during quality improvement analysis.

Clinical outcomes in pediatric hemodialysis patients in the USA: lessons from CMS' ESRD CPM Project

Although prospective randomized trials have provided important information and allowed the development of evidence-based guidelines in adult hemodialysis (HD) patients, with approximately 800 prevalent pediatric HD patients in the United States, such studies are difficult to perform in this population. Observational data obtained through the Center for Medicare & Medicaid Services' (CMS') End Stage Renal Disease (ESRD) Clinical Performance Measures (CPM) Project have allowed description of the clinical care provided to pediatric HD patients as well as identification of risk factors for failure to reach adult targets for clinical parameters such as hemoglobin, single-pool Kt/V (spKt/V) and serum albumin. In addition, studies linking data from the ESRD CPM Project and the United States Renal Data System have allowed evaluation of associations between achievement of those targets and the outcomes of hospitalization and death. The results of those studies, while unable to prove cause and effect, suggest that the adult ESRD CPM targets may assist in identifying pediatric HD patients at risk for poor outcomes.

Effect of change in renal replacement therapy modality on laboratory variables: a cohort study from the UK Renal Registry

BACKGROUND

Although previous comparisons have shown differences in biochemical and haematological variables between patients on haemodialysis and peritoneal dialysis and those with functioning transplants, these could be due to case mix rather than being due to differences in the types of renal replacement therapy (RRT). The longitudinal follow-up of individual patients after the change in modality has not hitherto been described.

METHODS

From the UK Renal Registry (UKRR) database of patients receiving RRT between 1 January 1997 and 31 December 2004, we identified two cohorts: 2033 patients who had been on either haemodialysis (HD) or peritoneal dialysis (PD) for at least a year and who subsequently underwent transplantation and then survived at least a year (PD + HD to Tp); and 892 patients who had been on PD for at least a year who changed to HD and then survived at least a year (PD to HD). In both cohorts, the following variables were studied for the four quarters before and after the change of modality: blood haemoglobin and serum, ferritin, albumin, bicarbonate, cholesterol, calcium, phosphate and parathyroid hormone (PTH) concentrations. No information on drug treatment was available.

RESULTS

In the PD + HD to Tp cohort, transplantation was associated with a rise in haemoglobin, albumin and bicarbonate, a fall in ferritin and phosphate, no change in calcium, a fall (but not to normal) in PTH and a transient rise in cholesterol concentrations. In the PD to HD group, the change in modality was associated with a significant temporary fall in haemoglobin, a progressive rise in ferritin, albumin, phosphate and PTH, no change in calcium and fall in bicarbonate and cholesterol concentrations.

CONCLUSION

The change from HD to PD is associated with a significant fall in the haemoglobin concentration; anticipation of this change might enable clinicians to ameliorate it. Persistent hyperparathyroidism is common after kidney transplantation.

Trends and outcomes associated with serum albumin concentration among incident dialysis patients in the United States

OBJECTIVE AND METHODS

Serum albumin concentrations are associated with mortality, and respond to nutritional and inflammatory states. To explore whether changing demographics and practice patterns in dialysis have influenced serum albumin concentrations, we analyzed trends in serum albumin among incident patients on dialysis from 1995 through 2004.

RESULTS

Mean serum albumin concentrations declined significantly over time, even after accounting for changes in age, diabetes, body size, and other factors. Although laboratory assays were not uniform within or across years, serum albumin declined over time, regardless of the reported laboratory lower limit of normal. Moreover, serum albumin retained its potent association with mortality over time. Lower serum albumin was especially hazardous among younger patients and blacks, and was less hazardous among persons with diabetes as a primary cause of kidney disease.

CONCLUSIONS

Despite higher body weights and the initiation of dialysis earlier in the course of progressive chronic kidney disease, hypoalbuminemia remains common and hazardous to persons starting dialysis.

Disparate outcomes in pediatric peritoneal dialysis patients by gender/race in the End-Stage Renal Disease Clinical Performance Measures project

Associations between achievement of adult Kidney Disease Outcomes Quality Initiative (KDOQI) targets for hemoglobin, adequacy and albumin, and race and gender were determined for pediatric peritoneal dialysis patients from the End-Stage Renal Disease (ESRD) Clinical Performance Measures (CPM) project for the period October 2004-March 2005. Fifty-six percent (427/761) of patients were male. Sixty-six percent (500/761) of patients were White. There were no differences in achievement of targets for adults by gender, and no differences in adequacy parameters by race. Blacks had lower mean hemoglobin levels than did Whites (11.1 +/- 1.6 g/dl vs 11.8 +/- 1.4 g/dl, P < 0.0001). Blacks were more likely to have mean hemoglobin levels < 10 g/dl (24% vs 11%, P < 0.0001) and less likely to achieve mean hemoglobin > 11 g/dl (56% vs 72%, P < 0.0001). Whites were more likely to achieve mean serum albumin levels > 4.0/3.7 g/dl [bromocresol green/bromocresol purple (BCG/BCP)] than Blacks were (35% vs 26%, P = 0.0376). In multivariate logistic regression models, White race was associated with mean hemoglobin levels > 11 g/dl [adjusted odds ratio (adj OR) 2.7, 95% confidence interval (CI) 1.7, 4.3] and mean serum albumin > 4.0/3.7 g/dl (BCG/BCP) (adj OR 1.9, 95% CI 1.3, 2.9]. Further study is needed of factors associated with anemia on peritoneal dialysis and barriers to its correction.

Lithium heparinised blood-collection tubes give falsely low albumin results with an automated bromcresol green method in haemodialysis patients

BACKGROUND

The aim of this study was to investigate the cause of markedly low albumin values determined by a bromcresol green (BCG) method in patients on haemodialysis.

METHODS

Serum and heparinised plasma from haemodialysis patients and normal controls were collected. Albumin was measured using Beckman bromcresol purple (BCP) and Roche BCG methods on the Beckman Synchron LX20.

RESULTS

The albumin in heparinised plasma determined by a BCG method was 33.3% lower than that of the BCP method in a haemodialysis patient. The albumin values determined by the BCP method were comparable to those measured by immunonephelometric analysis for this patient. Significantly lower albumin levels were also observed in lithium heparin plasma by a BCG method compared to the BCP method in both non-renal patients (31.2+/-3.8 vs. 34.1+/-4.1 g/L, p<0.001, n=30) and haemodialysis patients (28.6+/-3.5 vs. 32.8+/-3.7 g/L, p<0.001, n=30). This negative bias was directly correlated with heparin concentrations in the plasma. The BCP method did not show this dose-dependent bias.

CONCLUSIONS

Lithium heparin plasma can cause falsely low albumin values by an automated BCG method and the suitability of lithium heparin blood tubes should be carefully assessed for haemodialysis patients. The BCP method is free of this bias.

A formula to predict corrected calcium in haemodialysis patients

BACKGROUND

The conventional calcium correction formula (corrected total calcium (mmol/L) = TCa (mmol/L) + 0.02 [40 (g/L) - albumin (g/L)]) is broadly applied for the estimation of serum calcium in haemodialysis (HD) patients, despite the fact that it was not derived or validated in a HD population. A novel formula was derived and validated for corrected serum calcium in HD patients.

METHODS

Total calcium (TCa), ionized calcium (iCa(2+)), magnesium, phosphate, albumin and bicarbonate were collected from 60 HD patients to derive the formula. A validation set of 237 stable HD patients was then examined, and subjects were classified as hyper-, hypo- and normocalcaemic based on the iCa(2+). Agreement of the new formula was calculated with iCa(2+) as the gold standard, using the intraclass correlation coefficient (ICC). This was compared to the agreement between iCa(2+) and the following: uncorrected total serum calcium (TCa), the conventional correction formula, the Orrell formula and the Clase formula.

RESULTS

Using multiple linear regression the following formula was derived: corrected total calcium (mmol/L) = TCa (mmol/L) + 0.01 [30 (g/L) - albumin (g/L)]. The new formula had superior agreement compared to all of the other formulae. There was a statistically significant greater agreement between the new formula and the iCa(2+) as compared to the conventional formula (P < 0.01). However, the new formula did not significantly outperform the Orrell formula, the Clase formula or Total calcium.

CONCLUSIONS

The use of our simple new formula should enable more appropriate decision making compared to the conventional formula in the highly complex HD population.

Comparison of calcium phosphate product values using measurement of plasma total calcium and serum ionized calcium

Calcium phosphate product (Ca x Pi) is a clinically relevant tool to estimate the cardiovascular risk of patients with renal failure. In reports, mostly total serum calcium has been used. As measurement of serum ionized calcium has some benefits and is being used increasingly, we estimated the respective levels of calcium phosphate product using both total (t-Ca x Pi) and ionized calcium (ion-Ca x Pi). Fifty-eight healthy individuals and 180 hemodialysis (HD) patients from 2 centers were studied. Diagnostic accuracies for corresponding values of the t-Ca x Pi and ion-Ca x Pi were calculated using a GraphROC program. Of HD patients, 64% had t-Ca x Pi <4.4 mmol(2)/L(2) regarded as a desirable goal, and 10% had values over 5.6 mmol(2)/L(2) associated with a high cardiovascular risk. Based on GraphROC analysis, t-Ca x Pi of 4.4 mmol(2)/L(2) corresponded to a value of 2.2 mmol(2)/L(2) of ion-Ca x Pi and, respectively, t-Ca x Pi of 5.6 mmol(2)/L(2) corresponded 2.8 mmol(2)/L(2) of ion-Ca x Pi. Owing to the good agreement between the results in the 2 centers, these values for risk levels can be used in both centers. When measurement of ionized calcium is used, Ca x Pi values of 2.2 and 2.8 mmol(2)/L(2) can be used instead of generally used values of 4.4 and 5.6 mmol(2)/L(2) with total calcium.

Ethnic disparity in outcomes for pediatric peritoneal dialysis patients in the ESRD Clinical Performance Measures Project

Ethnicity information was collected for all pediatric peritoneal dialysis patients from the End-Stage Renal Disease (ESRD) Clinical Performance Measures (CPM) Project for the period October 2004 through March 2005. Associations between intermediate outcomes and Hispanic ethnicity were determined. Thirty percent (207/696) of patients in the final cohort were Hispanic, 24% (165/696) non-Hispanic black, and 46% (324/696) non-Hispanic white. Hispanics were more likely to be female, older, and have a lower mean height standard deviation score (SDS). There were no significant differences among ethnic/racial groups regarding clearance parameters. More Hispanics had a mean hemoglobin > or = 11 g/dl compared with non-Hispanic blacks and non-Hispanic whites (77% vs. 55% and 70%, P < 0.0001). More Hispanics compared with non-Hispanic blacks and non-Hispanic whites had a mean serum albumin > or = 4.0/3.7 g/dl [bromcresol green/bromcresol purple laboratory method (BCG/BCP)] (50% vs. 24% and 27%, respectively, P < 0.0001). In multivariate analyses, Hispanics remained significantly more likely to achieve a mean serum albumin > or = 4.0/3.7 g/dl (BCG/BCP) compared with non-Hispanic whites (referent) and were as likely to achieve clearance and hemoglobin targets. Pediatric Hispanic peritoneal dialysis patients experience equivalent or better intermediate outcomes of dialytic care compared with non-Hispanics. Further study is needed to understand associations of Hispanic ethnicity with outcomes such as hospitalization, transplantation, and mortality.

Improving Albumin Levels Among Hemodialysis Patients: A Community-Based Randomized Controlled Trial

BACKGROUND

Low albumin level is a strong predictor of mortality and morbidity among hemodialysis patients, yet few interventions are available to improve albumin levels. Moreover, the relative importance of nutritional barriers versus inflammation in contributing to hypoalbuminemia is unclear. We sought to determine whether targeting specific nutritional barriers will improve albumin levels.

METHODS

We conducted a randomized controlled trial involving 180 patients with baseline albumin levels less than 3.7 g/dL (<37 g/L) at 44 long-term hemodialysis facilities. Study coordinators identified and intervened on specific barriers present among intervention patients, whereas control patients continued to receive the usual care. Barriers targeted included poor nutritional knowledge, poor appetite, help needed with shopping or cooking, low fluid intake, inadequate dialysis dose, depression, difficulty chewing, difficulty swallowing, gastrointestinal symptoms, and acidosis.

RESULTS

At baseline, intervention and control patients had similar albumin levels, dietary intakes, levels of inflammatory markers, and numbers of nutritional barriers. After 12 months, intervention patients had greater increases in albumin levels compared with control patients (+0.21 versus +0.06 g/dL [+2.1 versus +0.6 g/L]; P < 0.01), as well as greater increases in energy intake (+4.1 versus -0.6 Kcal/d/kg; P < 0.001) and protein intake (+0.13 versus -0.06 g/d/kg; P < 0.001). The intervention appeared most effective for barriers related to poor nutritional knowledge, help needed with shopping or cooking, and difficulty swallowing. About half the subjects had elevated levels of inflammatory markers, but there was no relationship between change in levels of albumin and inflammatory markers.

CONCLUSION

A nutrition intervention tailored to patient-specific barriers resulted in modest improvements in albumin levels regardless of levels of inflammatory markers.

A combination of magnetic permeability detection with nanometer-scaled superparamagnetic tracer and its application for one-step detection of human urinary albumin in undiluted urine

A rapid (6.5 min) and simple one-step magnetic immunoassay (MIA) has been developed for analysis of human urinary albumin in near patient settings. Polyclonal rabbit anti-human albumin was used as a capture antibody and monoclonal mouse anti-human albumin as a detection antibody in a two-site immunometric assay requiring no additional washing procedures. The polyclonal anti-human albumin was conjugated to silica microparticles (solid phase) and the monoclonal antibody to dextran-coated nanoscaled superparamagnetic particles (tracer). Quantification of human albumin in undiluted urine was performed by adding 2 microL urine to a measuring vial containing solid-phase, superparamagnetic tracer and reaction buffer and then inverting the vial by hand for 20 s. The measuring vial was allowed to stand for 6 min prior to detection, in order for the solid-phase sediment to form at the bottom of the vial. Lastly, the measuring vial was placed into a magnetic permeability detector, which measured the enrichment of superparamagnetic tracer in the sediment due to complex formation with human albumin. Total analysis time was 6.5 min. A linear response was obtained for 0-400 mg/L albumin with a detection limit of 5 mg/L. The total coefficient of variation (CV) was 11% calculated from four consecutive runs on a urine sample containing 11.1 mg/L human albumin during 3 consecutive days. Human urinary albumin analysis was performed on 149 patient samples using the MIA technique and the obtained results showed good correlation with the hospital immunoturbidimetric reference method (y = 1.004x + 4.01, R2 = 0.978, N = 149) and a commercially available point of care albumin analysis provided by HemoCue Inc. (y = 0.98x + 5.8, R2 = 0.833, N = 90).

Outcomes for Adolescent Hispanic Hemodialysis Patients: Findings From the ESRD Clinical Performance Measures Project

BACKGROUND

There is limited information regarding outcomes of dialytic care for Hispanic adolescent hemodialysis patients.

METHODS

Ethnicity information was collected for all adolescent in-center hemodialysis patients for the Centers for Medicare & Medicaid Services 2000 End-Stage Renal Disease (ESRD) Clinical Performance Measures Project. Associations between intermediate outcomes and Hispanic ethnicity were determined. Associations of ethnicity and other demographic/clinical variables with hospitalization and transplantation during the 12-month follow-up period were examined.

RESULTS

Twenty-two percent of patients were identified as Hispanic; 40%, as non-Hispanic black; and 32%, as non-Hispanic white. Hispanic patients were younger and more likely to have congenital/urological causes of ESRD. More Hispanic patients had a mean single-pool Kt/V of 1.2 or greater compared with non-Hispanic blacks and non-Hispanic whites (87% versus 73% and 79%; P = 0.036). More Hispanic patients had a mean serum albumin level of 3.5/3.2 g/dL (bromcresol green/bromcresol purple method) or greater (> or = 35/32 g/L; 91% versus 82% and 76%; P = 0.017). More Hispanic patients compared with non-Hispanic blacks and non-Hispanic whites were dialyzed with a catheter for 90 days or longer (30% versus 21% and 23%; P = 0.027). In the final multivariate Cox proportional hazard models, Hispanic patients were at a slightly decreased risk for hospitalization compared with non-Hispanics (adjusted hazard ratio [adjHR], 0.63; P = 0.031) and were as likely to undergo a first transplantation as non-Hispanic whites (adjHR, 0.56; P = 0.099).

CONCLUSION

Adolescent Hispanic hemodialysis patients experience equivalent or better intermediate outcomes of dialytic care than non-Hispanics. They experienced a decreased risk for subsequent hospitalization and are as likely to undergo transplantation within 12 months as non-Hispanic whites.

The morbidity and cost implications of hemodialysis clinical performance measures

Clinical performance measures, including dialysis dose, hemoglobin, albumin, and vascular access, are the focus of monitoring and quality improvement activities. However, little is known about the implications of clinical performance measures for hospital utilization and health care costs. We obtained clinical performance measures and hospitalization records for a national random sample of 10,650 hemodialysis patients and analyzed the relationship between changes in clinical performance measures and hospital utilization after adjustment for patient demographic and medical characteristics. Higher hemoglobin, higher albumin, and fistula or graft use were independently associated with fewer hospitalizations, fewer hospital days, and decreased Medicare inpatient reimbursement. For example, a 0.5 g/dL higher hemoglobin, a 0.25 g/dL higher albumin, fistula use, and graft use were associated with hospitalization rate ratios of 0.90 (95% confidence interval 0.85, 0.96), 0.64 (0.53, 0.77), 0.60 (0.52, 0.69), and 0.79 (0.71, 0.89), respectively. Moreover, there was a 2-3-fold variation in hospital utilization across end-stage renal disease networks that was still evident after adjustment for patient characteristics and clinical performance measures. Clinical performance measures, especially albumin and vascular access, are strongly associated with hospital utilization and health care costs. These results highlight the importance of targeting nutrition and vascular access in quality improvement efforts. The marked variation in hospital utilization across networks deserves further examination.

Diabetes is the strongest risk factor for lower-extremity amputation in new hemodialysis patients

OBJECTIVE

End-stage renal disease (ESRD) patients, especially those with diabetes, have an increased risk of nontraumatic lower-extremity amputation (LEA). The present study aims to examine the association of demographic and clinical variables with the risk of hospitalization for LEA among incident hemodialysis patients.

RESEARCH DESIGN AND METHODS

The study population consisted of incident hemodialysis patients from the study years 1996-1999 of the ESRD Core Indicator/Clinical Performance Measures (CPM) Project. Cox proportional hazard modeling was used to identify factors associated with LEA.

RESULTS

Four percent (116 of 3,272) of noncensored incident patients had an LEA during the 12-month follow-up period. Factors associated with LEA included diabetes as the cause of ESRD or preexisting comorbidity (hazard ratio 6.4, 95% CI 3.4-12.0), cardiovascular comorbidity (1.8, 1.2-2.8), hemodialysis inadequacy (urea reduction ratio [URR] <58.5% (1.9, 1.1-3.3), and lower serum albumin level (1.6, 1.1-2.3). Among patients with diabetes, hemodialysis inadequacy and cardiovascular comorbidity were risk factors for LEA (2.6, 1.4-4.8, and 1.7, 1.1-2.6, respectively).

CONCLUSIONS

These data suggest that diabetes is a potent risk factor for LEA in new hemodialysis patients. In ESRD patients with diabetes, a multipronged approach may reduce the rate of LEA. Potentially beneficial strategies include adherence to hemodialysis adequacy guidelines, aggressive treatment of cardiovascular comorbidities, and the utilization of LEA prevention strategies recommended for the general population of patients with diabetes.

Anemia in pediatric dialysis patients in end-stage renal disease network 5

To identify demographic and clinical characteristics associated with failure to achieve hemoglobin levels >/=11 g/dl in prevalent pediatric end-stage renal disease (ESRD) patients, a cross-sectional analysis of patient clinical data collected by the Mid-Atlantic Renal Coalition in conjunction with the 2000 and 2001 ESRD Clinical Performance Measures Projects was performed. Ninety-nine patients (mean age 12.6 years, SD 5.4) contributed 119 observations to this analysis. Of patients on hemodialysis, 36.6% were anemic, and 39.5% of patients on peritoneal dialysis (PD) were anemic. Associations between age, race, gender, assigned cause of ESRD, Kt/V, transferrin saturation, time on dialysis, serum albumin, dialysis modality, and the achievement of target hemoglobin were examined. In multivariate logistic regression analyses examining age, dialysis modality, time on dialysis, and serum albumin, each 1-year increase in age was significantly associated with hemoglobin levels <11 g/dl [adjusted odds ratio (OR) 1.18, 95% confidence interval (CI) 1.06-1.32] and PD patients were more than twice as likely to have hemoglobin levels <11 g/dl (adjusted OR 2.62, 95% CI 0.98-7.04). Patients on dialysis for 6 months or more were less likely to be anemic than those on dialysis for less than 6 months (adjusted OR 0.39, 95% CI 0.16-0.99). In conclusion, increasing age, dialysis for less than 6 months, and treatment with PD were predictive of anemia in this population.

Differences in intermediate outcomes for Asian and non-Asian adult hemodialysis patients in the United States

BACKGROUND

There is a paucity of information regarding the clinical experience of Asian hemodialysis patients. This paper describes intermediate outcomes for adult Asian hemodialysis patients compared to Caucasians and African Americans.

METHODS

Dialysis facility staff abstracted clinical information on a national random sample of adult hemodialysis patients from October through December 2000. Associations of race with intermediate outcomes were tested by bivariate analyses and multivariable logistic regression modeling.

RESULTS

A total of 429 patients were identified as Asian, 4403 as Caucasians, and 3103 as African Americans. Asian and Caucasian patients were older than African Americans [mean 63.2 (+/-15.6), 63.9 (+/-15.2), and 57.7 (+/-14.7) years, P < 0.001], and had fewer years on dialysis [mean 3.5 (+/-3.8), 3.1 (+/-3.8), and 4.1 (+/-4.1) years, P < 0.001]. Ninety three percent of Asians, 87% of Caucasians, and 84% of African Americans had a mean Kt/V > or =1.2 (P < 0.001). In addition, 36% of Asians, 32% of Caucasians, and 26% of African Americans had an arteriovenous (AV) fistula as their vascular access (P < 0.001). Hemoglobin profiles were only slightly different among the three racial groups. More Asians and African Americans had a mean serum albumin > or =4.0/3.7 g/dL compared to Caucasians (33% and 31% compared to 27%, respectively, P < 0.001). In the final multivariable logistic regression model, Asians were twice as likely to have a mean Kt/V > or =1.2 compared to Caucasians (the referent group) [odds ratio (OR) (95% CI) 2.10 (1.33, 3.32), P < 0.01]. They experienced similar intermediate outcomes for vascular access, anemia management, and serum albumin compared to the majority racial group.

CONCLUSION

These findings indicate that adult hemodialysis Asian patients experience similar or better intermediate outcomes compared to the majority racial group. Further study is needed to determine if these results are associated with improved survival and less morbidity in this minority group.

Clinical performance measures: the changing status of peritoneal dialysis

BACKGROUND

The Peritoneal Dialysis-Clinical Performance Measures Project (PD-CPM) characterizes peritoneal dialysis within the U.S. Current survey results are reported and compared to those of previous years.

METHODS

Prevalence data from random national samples of adult peritoneal dialysis (PD) patients participating in the United States End-Stage Renal Disease (ESRD) program have been collected annually since 1995.

RESULTS

In 1995, 79% of the respondents used continuous ambulatory peritoneal dialysis (CAPD) rather than automated peritoneal dialysis (APD). The mean hematocrit (Hct) of PD patients was 32% and only 66% of individuals had a measurement of dialysis adequacy reported. The mean weekly Kt/Vurea (wKt/V) and weekly creatinine clearance (wCCr) reported for CAPD patients in 1995 were 1.9 and 67 L/1.73 m2/week, respectively. In 2000 the median age of PD patients was 55 years and 63% were white. The leading cause of ESRD was diabetes mellitus (34%) and 54% of adult PD patients performed some form of APD rather than CAPD. Age, sex, size, hematocrit, peritoneal permeability, dialysis adequacy, residual renal function and nutritional indices did not differ between APD and CAPD patients. The mean hemoglobin (Hb) for the 2000 PD-CPM population was 11.6 +/- 1.4 g/dL (mean +/- 1 SD) and 11% of patients had an average Hb below 10 g/dL. The average serum albumin was 3.5 +/- 0.5 g/dL by the bromcresol green method and 56% of subjects had an average serum albumin equal to or above 3.5 g/dL (or 3.2 g/dL by bromcresol purple). In 2000 85% of patients had a dialysis adequacy measurement reported and the mean calculated wKt/V and wCCr were 2.3 +/- 0.6 and 72.7 +/- 24.9 liters/1.73 m2/week for CAPD patients and 2.3 +/- 0.6 and 71.6 +/- 25.1 L/1.73 m2/week for APD patients. PD subjects had a mean body weight of 76 +/- 19 kg and body mass index (BMI) of 27.5 +/- 6.4 kg/m2. The protein equivalent of nitrogen appearance (nPNA) of these patients was 0.95 +/- 0.31 g/kg/day, their normalized creatinine appearance rate (nCAR) equaled 17 +/- 6.5 mg/kg/day, resulting in a percent lean body mass (%LBM) of 64 +/- 17% of actual body weight. Serum albumin correlated in a positive fashion with BMI, nPNA, nCAR and %LBM, but not with wCCr.

CONCLUSIONS

The majority of indicator variables monitored by the PD-CPM have improved since 1995. PD patients have higher hemoglobins and a greater proportion of patients meet the criteria for adequate dialysis. Serum albumin values, however, remain marginal and unchanged over the five-year project. Furthermore, serum albumin values fail to correlate with the intensity of renal replacement therapy and are not strongly correlated with alternative estimates of nutritional status.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Nutritional Status over Time in Hemodialysis and Peritoneal Dialysis

Abstract. Malnutrition is a risk factor for mortality in the dialysis population. So far, prospective studies comparing the time course of nutritional status in new hemodialysis (HD) and peritoneal dialysis (PD) patients have not been published. The aims of this study were to compare the time course of nutritional status in patients who were starting HD or PD and to identify the baseline determinants of that time course. In this prospective multicenter cohort study, data were collected from 3 (baseline) to 24 mo after the start of dialysis. Repeated measures ANOVA was used to establish the time course of nutritional status. Differences were adjusted for baseline characteristics. A total of 250 consecutive new patients were included: 132 started on HD, and 118 started on PD. A univariate analysis demonstrated a decrease in serum albumin (SA) in patients who started on HD and an increase in patients who started on PD. Body fat increased in PD; LBM did not change. The protein equivalent of nitrogen appearance normalized to ideal weight decreased in PD after 1 yr. In a multivariate analysis, SA at 2 yr was 2.0 g/L (95% confidence interval [CI], 0.3 to 3.8) higher in patients who started on PD compared with patients who started on HD. The increase in body fat was 3.2 kg (95% CI, 1.6 to 4.9) higher in women who started on PD than in others. Patients who had diabetes gained 2.3 kg (95% CI, 0.6 to 4.1) more fat than patients who did not have diabetes. Kt/Vureadid not affect the time course of nutritional status, but a higher Ktureawas associated with a higher SA at 24 mo. Nutritional status at the start of dialysis, gender, and diabetic status might be considered in making the choice for dialysis modality. Furthermore, providing a higher Ktureamay improve protein metabolism.

Increased albumin and fibrinogen synthesis in hemodialysis patients with normal nutritional status

This study compared the rates of whole-body proteolysis and of albumin and fibrinogen synthesis of seven hemodialysis patients (HD) with those of seven normal matched control subjects (C). HD patients had a normal nutritional and inflammatory status and serum albumin levels >3.5 g/dl. Endogenous leucine flux, albumin and fibrinogen fractional synthesis rate (FSR), and absolute intravascular synthesis rate (ASR) of albumin and fibrinogen all were evaluated by a primed/continuous infusion of 5,5,5-D3-L-leucine. Plasma volume was determined by the Evans blue dye dilution method. Endogenous leucine flux was significantly increased in HD (2.64 +/- 0.08 micromol/kg per min) compared with C (2.17 +/- 0.07 micromol/kg per min, P: < 0.05). Serum albumin concentrations were similar in HD and C. Plasma fibrinogen levels were significantly increased in HD compared with C (P: < 0.05). Plasma volume was greater in HD than in C (P: < 0.05). As a result, total intravascular pool of both albumin (141 +/- 7 versus 114 +/- 3 g/1.73 m(2), P: < 0.05) and fibrinogen (11.7 +/- 1 versus 6.7 +/- 0.5 g/1.73 m(2), P: < 0.05) were greater in HD than in C. Albumin FSR was not statistically different in HD and C. However, albumin ASR was significantly increased in HD than in C (13.7 +/- 2 versus 10.3 +/- 1 g/1.73 m(2) per d, P: < 0.05). Similarly, FSR of fibrinogen did not differ in HD and C groups, whereas ASR of fibrinogen was significantly higher in HD than in C (3.31 +/- 0.6 versus 1.94 +/- 0.3 g/1.73 m(2) per d, P: < 0.05). In summary, normoalbuminemic HD patients have an increased intravascular pool with a greater absolute synthesis rate of both albumin and fibrinogen and an increased rate of whole-body leucine flux.

Albumin-corrected calcium and ionized calcium in stable haemodialysis patients

BACKGROUND

It is ionized calcium that is physiologically active and under homeostatic control; however, total calcium is more conveniently measured. Formulae for correction of calcium to account for albumin binding have not been validated in a dialysis setting.

METHODS

We measured ionized calcium simultaneously with total calcium (t[Ca]), albumin, total protein and pH before dialysis in 50 stable outpatients and convalescent inpatients.

RESULTS

Although 92% of patients were taking calcium supplements and 70% taking alphacalcidol, 11 patients (22%) had ionized hypocalcaemia. To facilitate comparison of calculated ionized calcium, measured total calcium (t[Ca]), and 'corrected' calcium (c[Ca]), with the criterion measure of ionized calcium, all measurements were converted to z scores, standardized on the normal range for each variable. Results are expressed as intraclass correlation coefficients (ICC: 0, all differences are due to error; 1, all differences are due to between patient variation).

CONCLUSIONS

None of the published formulae greatly improved the test characteristics beyond simply using the total calcium. A correction formula in widespread use (Payne), quoted in reference texts, agreed less well with ionized calcium than did the unadjusted measured calcium. Correction formulae should be abandoned in favour of the use of uncorrected calcium. In cases of doubt, ionized calcium should be directly measured.

Albumin as an outcome measure in haemodialysis in patients: the effect of variation in assay method

BACKGROUND

Serum/plasma albumin is an important predictor of future mortality/morbidity in haemodialysis (HD) patients and has been proposed as an important audit measure. Different methods of albumin assay give different results and the bias between methods may be greater in renal failure patients.

METHODS

Albumin concentration in plasma was measured by three methods, two dye-binding methods (bromocresol green (BCG) and bromocresol purple (BCP)) and an immuno-turbidimetric (ITM) method, in 143 HD patients (group I) and 49 non-renal patients (group II). Comparisons were made between means, variation in differences across a range of albumin concentrations and on the percentage of patients within the normal range.

RESULTS

In HD patients (group I), BCG over-estimated plasma albumin compared with the other two methods. The difference could be as much as 10 g/l and was more marked in hypoalbuminaemic patients. The BCP method gave results closer to the ITM method, particularly in HD patients. These differences were less marked in group II patients but both methods overestimated albumin compared with the ITM method. Using the BCG local laboratory normal range, 84% of HD patients had plasma albumin concentrations within the normal range but this fell to 57% if the BCP results were used.

CONCLUSIONS

The method for determining albumin concentration has a marked effect on the results particularly in HD patients. BCG, the most commonly used method, gives higher results than other methods and correlates poorly with an immunological method. These differences make comparative audit between nephrology units difficult and have implications for other biochemical variables and other specialties.

Racial/ethnic analysis of selected intermediate outcomes for hemodialysis patients: results from the 1997 ESRD Core Indicators Project

Principal goals of the End-Stage Renal Disease (ESRD) Core Indicators Project are to improve the care provided to ESRD patients and to identify categorical variability in intermediate outcomes of dialysis care. The purpose of the current analysis is to extend our observations about the variability of intermediate outcomes of ESRD care among different racial and gender groups to a previously unreported group, Hispanic Americans. This group is a significant and growing minority segment of the ESRD population. A random sample of Medicare-eligible adult, in-center, hemodialysis patients was selected and stratified from an end-of-year ESRD patient census for 1996. Of the 6,858 patients in the final sample, 45% were non-Hispanic whites, 36% were non-Hispanic blacks, and 11% were Hispanic. Whites were older than blacks or Hispanics (P < 0.001). Hispanics were more likely to have diabetes mellitus as a primary diagnosis than either blacks or whites (P < 0.001). Even though they received longer hemodialysis times and were treated with high-flux hemodialyzers, blacks had significantly lower hemodialysis doses than white or Hispanic patients (P < 0.001). The intradialytic weight losses were greater for blacks (P < 0.05). The delivered hemodialysis dose was lower for blacks than for whites or Hispanics whether measured as a urea reduction ratio (URR) or as the Kt/V calculated by the second generation formula of Daugirdas (median 1. 32, 1.36, and 1.37, respectively, P < 0.001). Hispanics and whites had modestly higher hematocrits than blacks (33.2, 33.2, and 33.0%, respectively, P < 0.01). There was no significant difference among groups in the weekly prescribed epoetin alfa dose ( approximately 172 units/kg/week). A significantly greater proportion of Hispanic patients had transferrin saturations >/=20% compared with the other two groups (P < 0.001). Logistic regression modeling revealed that whites were significantly more likely to have serum albumin <3. 5(BCG)/3.2(BCP) gm/dL (OR 1.4, p < 0.01); blacks were significantly more likely to have a delivered Kt/V < 1.2 (OR 1.4, P < 0.001) and hematocrit <30%, (OR 1.2; P < 0.05) and both blacks and Hispanics were significantly more likely to have a delivered URR < 65% (OR 1.5, P < 0.001 and 1.2, P < 0.05, respectively).

Trends in clinical indicators of care for adult peritoneal dialysis patients in the United States from 1995 to 1997. ESRD Core Indicators Workgroup

BACKGROUND

This article describes the changes in four core indicator variables: dialysis adequacy, hematocrit, serum albumin, and blood pressure in peritoneal dialysis CAPD and cycler patients over a three-year period.

METHODS

A national random sample of adult peritoneal dialysis patients in the United States was drawn each study period. Clinical data abstraction forms were completed by facility staff for patients selected for the sample, returned to the respective network, then forwarded to the Health Care Financing Administration for analysis.

RESULTS

The mean weekly Kt/V urea for CAPD patients increased from 1.91 in 1995 to 2.12 in 1997 (P < 0.001) and for cycler patients, from 2.12 in 1996 to 2.24 in 1997 (P < 0.05). The mean weekly creatinine clearance for CAPD patients increased from 61.48 liter/week/1.73 m2 in 1995 to 65.84 liter/week/1.73 m2 in 1997 (P < 0.05). For cycler patients, it increased from 63.37 liter/week/1.73 m2 in 1996 to 67.45 liter/week/1.73 m2 in 1997 (P < 0.05). Despite this increase in adequacy values, less than 40% of peritoneal dialysis patients in 1997 had weekly Kt/V urea or creatinine clearance values that met subsequently published National Kidney Foundation's Dialysis Outcomes Quality Initiative (DOQI) guidelines. These data suggest that the dialysis prescription may not be adequately modified to compensate for increased body weight and for decreased residual renal function as years on dialysis increase. The average hematocrit value increased modestly in both CAPD and cycler patients from 1995 to 1997, and the number of patients with a hematocrit of less than 25% decreased from 6% in 1995 to 1.4% in 1997 (P < 0.001). Both serum albumin values and systolic and diastolic blood pressure values were essentially unchanged during the three-year period of observation.

CONCLUSIONS

Despite improvements in dialysis adequacy and hematocrit values, there remains much room for improvement in these core indicator values.

The effect of blood draw methodology on selected nutritional parameters in chronic renal failure

The reliability and validity of any clinical laboratory test is directly affected by the integrity of the blood specimen obtained for analysis. Renal failure patients undergo a high number of laboratory tests, primarily to monitor the quality of care. Subsequent tests to confirm laboratory abnormalities are costly and place the patient at unnecessary risk for additional blood loss. Three of the four Health Care Financing Administration core clinical outcome indicators have nutritional implications and use laboratory values as part of review criteria: adequacy of dialysis, albumin, and anemia. National Kidney Foundation-Dialysis Outcomes Quality Initiative (DOQI) Clinical Practice Guidelines have recommended standardized predialysis and postdialysis blood draw procedures to increase accuracy for adequacy of dialysis. The National Committee on Clinical Laboratory Standards publishes peer-reviewed guidelines for venipuncture. Together, the adoption of these standards would minimize preanalytical variation and improve the data used to monitor the quality of care in renal patients.

Barriers to adequate protein nutrition among hemodialysis patients

OBJECTIVE

Determine the relative importance of potential medical, behavioral, and socioeconomic barriers to adequate protein nutrition among hemodialysis patients.

DESIGN

Cross-sectional study.

SETTING

All 22 chronic hemodialysis units in northeast Ohio.

PATIENTS

298 randomly selected chronic hemodialysis patients.

INTERVENTION

We interviewed and abstracted the chart of each patient to assess protein nutritional status (albumin and protein catabolic rate), potential medical barriers (poor appetite, inadequate dialysis, bioincompatible dialysis membrane, difficulty chewing, and comorbid conditions), potential behavioral barriers (knowledge of protein containing foods and dietary noncompliance), and potential socioeconomic barriers (expense of protein containing foods and needing help shopping and cooking).

MAIN OUTCOME MEASURE

We used logistic regression to examine the relationship between protein nutritional status and potential barriers.

RESULTS

Albumin levels of <35 g/L were independently associated with Kt/V of <1.2 (odds ratio, 2.4), having more than three comorbid conditions (odds ratio, 4.0), inability to name any protein-containing foods (odds ratio, 2. 3), and needing help shopping and cooking (odds ratio, 2.6). Normalized protein catabolic rate of <1.0 g/kg/d was independently associated with poor appetite (odds ratio, 3.3), Kt/V of <1.2 (odds ratio, 3.1), and dietary compliance as indicated by low interdialytic fluid gain (odds ratio, 2.2).

CONCLUSION

Three medical factors (poor appetite, inadequate dialysis, and comorbid conditions), two behavioral factors (lack of knowledge of protein containing foods and low interdialytic fluid gain), and one socioeconomic factor (needing help shopping and cooking) are independently associated with inadequate protein nutrition among hemodialysis patients. Further work is needed to develop interventions to overcome these barriers and to determine the effect of such interventions on protein nutrition and patient mortality and morbidity.

The Kidney Outcomes Prediction and Evaluation (KOPE) study: a prospective cohort investigation of patients undergoing hemodialysis. Study design and baseline characteristics

PURPOSE

The purpose of the Kidney Outcomes Prediction and Evaluation (KOPE) study, was to more fully characterize the end-stage renal disease (ESRD) population with respect to social, psychological, and clinical characteristics, and to prospectively study the biomedical, social, and psychological factors that influence a range of ESRD outcomes in a large observational study of black and white patients on hemodialysis. This paper focuses on the KOPE study design as well as characteristics of patients at baseline.

METHODS

KOPE was a prospective cohort investigation of patients treated at four dialysis centers in Forsyth County, North Carolina. Participants were interviewed at the dialysis centers, semi-annually over a 3 1/2 year period. Prevalent cases who were being treated with hemodialysis at the initiation of the study were enrolled into KOPE. Incident cases were subsequently enrolled as they presented to the participating units for hemodialysis. A total of 304 prevalent and 162 incident cases were enrolled into the study. The baseline health and sociodemographic characteristics of KOPE participants reported in this paper were obtained from medical records and Southeast Kidney Council data. Laboratory values taken within a 30-day interval around the baseline interview are also reported.

RESULTS

KOPE participants differ from national statistics on race, age, and gender. Differences between KOPE participants and patients living in the region, but who did not participate in the study, can be explained by our recruitment criteria.

CONCLUSIONS

KOPE will enable the characterization of the ESRD population, identification of factors related to poor outcomes, and identification of opportunities for interventions to prevent death and morbidity.

Factors predicting malnutrition in hemodialysis patients: a cross-sectional study

Signs of protein-energy malnutrition are common in maintenance hemodialysis (HD) patients and are associated with increased morbidity and mortality. To evaluate the nutritional status and relationship between various parameters used for assessing malnutrition, we performed a cross-sectional study in 128 unselected patients treated with hemodialysis (HD) thrice weekly for at least two weeks. Global nutritional status was evaluated by the subjective global nutritional assessment (SGNA). Body weight, skinfold thicknesses converted into % body fat mass (BFM), mid-arm muscle circumference, hand-grip strength and several laboratory values, including serum albumin (SA1b), plasma insulin-like growth factor I (p-IGF-I), serum C-reactive protein (SCRP) and plasma free amino acids, were recorded. Dose of dialysis and protein equivalence of nitrogen appearance (nPNA) were evaluated by urea kinetic modeling. The patients were subdivided into three groups based on SGNA: group I, normal nutritional status (36%); group II, mild malnutrition (51%); and group III, moderate or (in 2 cases) severe malnutrition (13%). Clinical factors associated with malnutrition were: high age, presence of cardiovascular disease and diabetes mellitus. nPNA and Kt/V(urea) were similar in the three groups. However, when normalized to desirable body wt, both were lower in groups II and III than in group I. Anthropometric factors associated with malnutrition were low body wt, skinfold thickness, mid-arm muscle circumference (MAMC), and handgrip strength. Biochemical factors associated with malnutrition were low serum levels of albumin and creatinine and low plasma levels of insulin-like growth factor 1 (IGF-1) and branched-chain amino acids (isoleucine, leucine and valine). The serum albumin (SAlb) level was not only a predictor of nutritional status, but was independently influenced by age, sex and SCRP. Plasma IGF-1 levels also reflected the presence and severity of malnutrition and appeared to be more closely associated than SAlb with anthropometric and biochemical indices of somatic protein mass. Elevated SCRP (> 20 mg/liter), which mainly reflected the presence of infection/inflammation and was associated with hypoalbuminemia, was more common in malnourished patients than in patients with normal nutritional status, and also more common in elderly than in younger patients. Plasma amino acid levels, with the possible exception of the branched-chain amino acids (isoleucine, leucine, valine), seem to be poor predictors of nutritional status in hemodialysis patients.