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Background: The choice of vascular access type is an important aspect of care for incident hemodialysis patients. However, data from the Centers for Medicare & Medicaid Services (CMS) Medical Evidence Report (form CMS-2728) identifying the first access for incident patients have not previously been validated. Medicare began requiring that vascular access type be reported on claims in July 2010. We aimed to determine the agreement between the reported vascular access at initiation from form CMS-2728 and from Medicare claims., Methods: This retrospective study used a cohort of 9777 patients who initiated dialysis in the latter half of 2010 and were eligible for Medicare at the start of renal replacement therapy to compare the vascular access type reported on form CMS-2728 with the type reported on Medicare outpatient dialysis claims for the same patients. For each patient, the reported access from each data source was compiled; the percent agreement represented the percent of patients for whom the access was the same. Multivariate logistic analysis was performed to identify characteristics associated with the agreement of reported access., Results: The two data sources agreed for 94% of patients, with a Kappa statistic of 0.83, indicating an excellent level of agreement. Further, we found no evidence to suggest that agreement was associated with the patient characteristics of age, sex, race, or primary cause of renal failure., Conclusion: These results suggest that vascular access data as reported on form CMS-2728 are valid and reliable for use in research studies.

Background/aims: Hemoglobin level variability in hemodialysis patients is common, and has been associated with comorbidity, intercurrent illness, and mortality risk. We aimed to describe the influence of anemia management interventions (erythropoiesis-stimulating agents [ESAs], intravenous iron, and transfusions) on hemoglobin variability., Methods: We studied all Medicare primary payer hemodialysis patients who survived and had ESA claims in the first 6 months of 2004 (n = 159,720). Monthly hemoglobin values were categorized as low (<11 g/dl), intermediate (11-12.5 g/dl), and high (>12.5 g/dl). Variability groups were classified based on lowest and highest hemoglobin categories during a 6-month observation period. ESA, intravenous iron, and transfusion use were characterized by variability group., Results: Patients with consistently low or low and intermediate hemoglobin received the highest ESA doses and the most frequent transfusions, while patients with consistently or intermittently intermediate or high hemoglobin received lower ESA doses and fewer transfusions. Intravenous iron doses were highest initially for patients with consistently high hemoglobin; these doses subsequently declined. Iron doses were lowest for patients with consistently intermediate hemoglobin., Conclusions: Anemia management protocols describing coordinated administration of ESAs and iron may help to increase the number of patients achieving target hemoglobin levels., (Copyright 2009 S. Karger AG, Basel.)

Background/objectives: Awareness of hemoglobin level variability in dialysis patients is increasing, as is interest in its potential implications. In this retrospective, national study of associations between the degree of hemoglobin level variability in the first 6 mo of 2004 and subsequent mortality rates in the following 6 mo, 159,720 hemodialysis patients receiving epoetin therapy were studied., Design, Setting, Participants, Measurements: Monthly hemoglobin values were categorized as low (L; < 11 g/dl), intermediate (I; 11 to 12.5 g/dl), and high (H; >12.5 g/dl). Variability groups were classified on the basis of the lowest and highest hemoglobin categories seen during the 6-mo observation period: low-low (L-L), 1.4%; intermediate-intermediate (I-I), 6.0%; high-high (H-H), 2.3%; low-intermediate (L-I), 18.3%; intermediate-high (I-H), 31.7%, and low-high (L-H), 40.2%., Results: On multivariate analysis, adjusted hazards ratios for subsequent mortality events were as follows: I-I, 1.0 (reference category); I-H, 1.02 (95% confidence interval [CI] 0.95 to 1.11); H-H, 1.06 (95% CI 0.93 to 1.21); L-H, 1.19 (95% CI 1.10 to 1.28); L-I, 1.44 (95% CI 1.33 to 1.56), and L-L, 2.18 (95% CI 1.93 to 2.45). Persistently and transiently low hemoglobin levels and highly variable hemoglobin levels were associated with increased risk of death; transiently and persistently high hemoglobin levels were not associated with increased risk of death. Bayesian modeling indicated that > or =3 mo with hemoglobin levels <11 g/dl may be associated with of increased risk of death., Conclusions: Number of months with hemoglobin values below the target range, rather than hemoglobin variability itself, may be the primary driver of increased risk of death. Further research is needed to distinguish cause from effect and to understand the underlying mechanisms.

Background: This study investigates provider practices regarding recombinant human erythropoietin (rHuEPO) dose when patient hemoglobin levels exceeded National Kidney Foundation-Dialysis Outcomes Quality Initiative target levels and reached 13 g/dL or greater (>or=130 g/L)., Methods: The study population (N = 167,796) was hemodialysis patients prevalent on January 1, 2003, who were on renal replacement therapy at least 90 days with Medicare as primary payer and rHuEPO claims in 2 or more consecutive months. Patient characteristics were obtained from the Centers for Medicare & Medicaid Services (CMS) Medical Evidence Report, and comorbid conditions were determined from Medicare claims. Providers and rHuEPO claims were linked by using CMS-assigned provider numbers and the CMS Annual End-Stage Renal Disease Facility Survey. Between-provider differences in patient characteristics were examined by using chi-square test, and provider effect on appropriate response, by using logistic regression., Results: DaVita's percentage of monthly claims for patients with hemoglobin levels of 13 g/dL or greater (>or=130 g/L; 16.7%) and mean monthly rHuEPO dose (54,299 units) were highest. Dialysis Clinic Inc's percentage of such claims (2.0%) and mean monthly dose (38,687 units) were lowest. Dialysis Clinic Inc, Fresenius, and Renal Care Group had the highest percentage of recommended dose adjustments (mean, 70% of units); hospital-based units had the lowest (59%). By adjusted odds ratio, adjustments were 20% more likely for Dialysis Clinic Inc, Fresenius, and Renal Care Group compared with DaVita, National Nephrology Associates, hospital-based units, and independents (17% to 28% less likely)., Conclusion: rHuEPO dose reduction practices are dependent on specific dialysis providers and whether units are hospital based or independent.

National payment policies target a hemoglobin range of 11 to 12.5 g/dl for patients with ESRD. However, clinical complications and provider practices may contribute to wide fluctuations over time. This study evaluated the frequency with which patients maintain stable hemoglobin levels below, within, and above the Centers for Medicare & Medicaid Services target range and assessed patterns of hemoglobin level change that resulted in large fluctuations across the target range during a 6-mo period. All hemodialysis patients who survived the first 6 mo of 2003, had Medicare as primary payer, and had Medicare outpatient erythropoietin claims in each of the first 6 mo of 2003 (n = 152,846) were studied. Six patient groups were defined on the basis of patterns of hemoglobin level fluctuation: Consistently low (<11 g/dl), consistently target range (11 to 12.5 g/dl), consistently high (> or =12.5 g/dl), low-amplitude fluctuation with low hemoglobin levels, low-amplitude fluctuation with high hemoglobin levels, and high-amplitude fluctuation. Only 10.3% of patients maintained stable hemoglobin levels during the 6 mo and only 6.5% in the target range. The consistently low group had the highest percentage of hospitalizations and the highest number of comorbid conditions. High-amplitude fluctuation was the most common pattern (39.5%), with hemoglobin levels falling below and rising above the target range during the 6-mo period. Hemoglobin levels in almost 90% of patients are in some degree of flux at any point in time, and the fluctuation is highly associated with clinical complications and provider practices.

The size of the prevalent ESRD population in the United States increased dramatically during the 1990s, from 196,000 in 1991 to 382,000 in 2000. Incidence also increased considerably during the same period, from 53,000 to 93,000 per year. If previous trends in ESRD incidence and prevalence continue, then current levels of health care resources that are devoted to the care of these patients will eventually be unable to meet the demand. This study discusses a Markov model developed to predict ESRD incidence, prevalence, and mortality to the year 2015 and incorporating expected changes in age/race distributions, diabetes prevalence, ESRD incidence, and probability of death. The model predicted that by 2015 there will be 136,166 incident ESRD patients per year (lower/upper limits 110,989 to 164,550), 712,290 prevalent patients (595,046 to 842,761), and 107,760 ESRD deaths annually (96,068 to 118,220). Incidence and prevalence counts are expected to increase by 44 and 85%, respectively, from 2000 to 2015 and incidence and prevalence rates per million population by 32 and 70%, respectively. The financial and human resources that will be needed to care for these patients in 2015 will be considerably greater than in 2005.

Background: The impact of dialyzer reuse on the mortality of hemodialysis patients is debated. This study assesses reuse-associated mortality across US dialysis provider systems (for-profit, not-for-profit; hospital-based, and freestanding units) in incident patients., Methods: Incident Medicare hemodialysis patients who initiated dialysis therapy from January 1, 2000, to December 31, 2001, were included and followed up to December 31, 2002. A 3-month entry period was used to determine comorbidity and disease severity. Applying various analytic approaches, mortality rates for patients treated with reused (or reprocessed) or single-use dialyzers were compared. Because of differences among dialysis units, facility clustering was addressed., Results: Of 75,831 patients, 61,391 patients (81.0%) were classified as on reuse, and 14,440 patients (19.0%), as on single use, as of the start of follow-up. The overall mortality rate was 25.0/100 patient-years. No difference in mortality risk was found between patients treated with reuse compared with single use in an intent-to-treat approach (hazard ratio, 0.98; 95% confidence interval, 0.94 to 1.02; P = 0.266) after adjusting for chain affiliation, for-profit status, year of dialysis inception, age, sex, race, renal diagnosis, comorbidity, and hospitalization days. Findings were similar in an as-treated approach (hazard ratio, 0.97; 95% confidence interval, 0.93 to 1.01; P = 0.136). No survival advantage associated with single use was found for subgroups., Conclusion: No overall survival advantage or disadvantage is associated with dialyzer reuse compared with single use in incident hemodialysis patients in the United States; however, continued monitoring is advised.

Background: The cost of care for end-stage renal disease (ESRD) is known to be high. The factors responsible for higher ESRD cost develop during chronic kidney disease (CKD), where the data on distribution of cost are limited., Methods: This retrospective cohort study of 1995 through 1998 incident dialysis patients was performed to study the distribution of costs during the 24 months prior to initiation of dialysis. Patient data were obtained from the Centers for Medicare and Medicaid Services (CMS). Patients who were Medicare eligible for at least 2 years prior to initiation of dialysis were included in the study. Financial data were obtained from Medicare Part A and Part B claims and inflationary adjustments were made. The study period was divided into four segments based on overall distribution of cost., Results: The mean age was 75 years, 51% were males, 73% were white, and 22% were black. Overall, patient comorbidity increased significantly during the study years. Cost showed a sharp increase in the last 6 months prior to initiation of dialysis. Hospitalization was the major component of cost throughout study period. Patients who initiated hemodialysis incurred a higher cost compared to patients who initiated other modes of kidney replacement therapy. Patients with diabetes or cardiovascular disease incurred higher cost compared to those who had no diabetes or cardiovascular disease, respectively., Conclusion: These data showed that hospitalization was the major component of the sharp increase in cost around the initiation of dialysis. Increased comorbidity was associated with higher cost. A focus on timely management of CKD may prevent future morbidity and costs.

Background: The reuse of haemodialysers has been practiced in the United States for >20 years. We investigated mortality and hospitalization risk according to various reuse practices, testing the hypothesis that outcomes are improved in patients treated with dialysers cleaned with bleach and sterilized with formaldehyde., Methods: We studied 1998 and 1999 incident Medicare haemodialysis patients, with follow-up through December 31, 2000 (49 273 patients). Clinical conditions and dialysis therapy were characterized from Medicare claims data. Included were patients who could be linked to a dialysis provider. Demographic characteristics were obtained from the Centers for Medicare and Medicaid Services (CMS) Medical Evidence Report. Mortality information was obtained from the CMS ESRD Death Notification; hospitalization information, from Medicare in-patient claims files. Data on reuse practices were obtained from the annual survey of haemodialysis units conducted by the Centers for Disease Control and Prevention., Results: Cox regression analyses found no significant differences in mortality or first-hospitalization risk for patients in dialysis units not using bleach as a cleaning agent. Outcomes for patients treated in units using glutaraldehyde did not vary according to use of bleach. In the analysis of first-hospitalization risk, there was no difference according to various germicide/bleach combinations. Overall, there was no significant difference in relative risk of death or in hospitalization risk among the reuse groups (including the no-reuse group)., Conclusions: For the 1998-1999 period, reuse practices were not associated with a survival advantage or disadvantage. Our findings may reflect the National Kidney Foundation's 1997 introduction of clinical practice guidelines, the intent of which was to bring about increased consistency of care within the dialysis community in the United States.

Background: Dialysis access is critical for therapy delivery. Few studies have linked type of dialysis access to patient survival in the elderly population., Methods: We included 1995 to 1997 incidence Medicare hemodialysis patients (N = 66,595) who were 67 years and older at dialysis therapy initiation. Medicare Physician/Supplier claims were used to determine initial access type: simple fistula, autologous vein graft, synthetic graft, and hemodialysis catheter. We used International Classification of Diseases, Ninth Revision, Clinical Modification, codes to determine vascular access placement for renal failure. A Cox regression analysis assessed risk for death within 1 year, with explanatory variables of incidence year, age, sex, race, diabetes, initial access type, body mass index, days from first access placement date to initial dialysis date, and serum albumin, creatinine, and blood urea nitrogen levels., Results: One-year crude death rates were 24.9%, 27.2%, 28.1%, and 41.5% for patients with simple fistulae, autologous vein grafts, synthetic grafts, and hemodialysis catheters, respectively. Patients with simple fistulae (the reference) had the lowest (P < 0.0001) likelihood of death compared with those with synthetic grafts (hazard ratio [HR], 1.160; 95% confidence interval [CI], 1.084 to 1.241) or catheters (HR, 1.696; 95% CI, 1.593 to 1.806). No difference (P > 0.09) in mortality risk was detected between simple fistulae and autologous vein grafts or between autologous vein grafts and synthetic grafts., Conclusion: In the US Medicare dialysis population, type of initial hemodialysis access was associated with 1-year mortality. Mortality risks were (in ascending order) fistulae, grafts, and catheters.

Background: Anemia is a common complication of advancing chronic kidney disease, yet little is known about the consistency of anemia treatment before end-stage renal disease (ESRD) and mortality on dialysis therapy., Methods: We studied 89,193 incident Medicare patients with ESRD in 1995 to 1997 aged 67 plus years with claims 2 years before their dialysis therapy initiation. Patients were classified as follows: no epoetin, 25% or less (least consistent), greater than 25% to 50%, greater than 50% to 75%, and greater than 75% (most consistent) epoetin treatment in the available months from the first pre-ESRD epoetin dose to the first ESRD service date. Cox regression modeled the risk for 1-year death in the post-ESRD period, adjusting for age, sex, race, diabetic status, albumin level, and incidence year., Results: Sixty percent of patients had hematocrits less than 30% at ESRD initiation, yet only 15.6% (N = 13,877) had epoetin claims before ESRD. The most consistent epoetin treatment group had hematocrits increase from 27.5% to 30.8% (P < 0.0001) by month 4 of treatment. Patients with the most consistent epoetin treatment had a greater mean hematocrit (29.2% +/- 0.11%; P < 0.0001) and albumin level (3.31 +/- 0.01 g/dL [33.1 g/L]) at initiation than those with the least consistent treatment (28.1% +/- 0.10% and 3.21 +/- 0.01 g/dL [32.1 g/L], respectively). The relative risk for death in patients with the least consistent versus the most consistent (the reference) epoetin treatment was 1.460 (95% CI, 1.245 to 1.713; P < 0.0001) 1 year after the first ESRD service date., Conclusion: Elderly patients with consistent pre-ESRD epoetin treatment had lower risks for death in the first year of dialysis therapy after ESRD initiation., (Copyright 2002 by the National Kidney Foundation, Inc.)

Background: Comparisons of mortality outcomes between peritoneal dialysis (PD) and hemodialysis (HD) patients have shown varying results, which may be caused by the unequally distributed clinical conditions of patients at initiation. To address this issue, we evaluated the clinical characteristics of 105,954 patients at the initiation of PD and HD, using the U.S. national incidence data on treated end-stage renal disease from the Medical Evidence Form, 1995 to 1997., Methods: A general linear model was used to analyze differences of age, albumin, creatinine, blood urea nitrogen (BUN), and hematocrit; categorical data analysis to evaluate body mass index (BMI), grouped into four categories: < 19, 19-25 (< 25), 25-30 (< 30), and 30+; and logistic regression to assess the likelihood of initiating PD versus HD. Diabetics (DM) were analyzed separately from non-diabetics (NDM). Explanatory variables in the logistic regression included incidence year, race, gender, age, BMI, albumin, creatinine, BUN, and hematocrit. Race included white and black. Age was categorized into four groups: 20-44, 45-64, 65-74, and 75+., Results: At the initiation of dialysis PD patients were approximately 6 years younger (P < 0.0001) than HD patients. PD patients also had higher (P < 0.0001) albumin (+0.35 g/dL for DM and +0.23 g/dL for NDM) and hematocrit (+1.64% for DM and +1.71% for NDM) levels, and lower (P < 0.04) BUN (-8.75 mg/dL for DM and -5.24 mg/dL for NDM) and creatinine (-0.51 mg/dL for DM and -0.23 mg/dL for NDM) levels than HD patients. Whites had a higher (P < 0.0001) likelihood of starting PD than blacks, and patients with BMI <19 had a lower (P < 0.0001) chance of beginning on PD., Conclusion: PD patients had favorable clinical conditions at the initiation of dialysis, which should be taken into consideration when comparing dialysis outcomes between the two modalities.

Background: Patients initiating with peritoneal dialysis (PD) have favorable clinical conditions compared with hemodialysis (HD) patients, which may contribute to the varying results found in studies of mortality across the two therapies., Methods: National incidence data of end-stage renal disease patients from 1995 to 1997 were used, excluding the first 90 days of treatment and including all patients who were on either PD or HD on day 91. Patients were then followed for a one-year period. A Cox proportional hazards regression analysis was used, separating diabetics and non-diabetics, and two statistical models were applied. Model 1 included race, gender, age, initial modality, and incidence year as explanatory variables. Model 2 added body mass index (BMI), initial levels of serum albumin, creatinine, and blood urea nitrogen., Results: Age was most highly associated with mortality, followed by biochemical variables, BMI, gender, and dialysis modality. In diabetics, the hazard ratio (HR) from Model 1 indicated no difference [1.046, 95% confidence limits (CL) 0.989-1.105; P> 0.1, HD was the reference] in mortality between PD and HD, while Model 2 demonstrated that PD patients had a 13.4% (1.134, CL 1.072-1.100, P < 0.0001) higher chance of death. In non-diabetics, hazard ratios (HRs) from Models 1 and 2 indicated that PD patients had a 23.5% (0.765, 0.722-0.812, P < 0.0001) and 11.9% (0.881, 0.30-0.935, P < 0.0001), respectively, lower likelihood of death than HD patients., Conclusion: Our study indicates that the results changed depending on the analytical methods used. We recommend that, due to the unequally distributed clinical conditions of patients at initiation, comparisons of mortality outcomes between dialysis modalities should be made with caution.

Aim: We evaluated 152 sevelamer hydrochloride treated Medicare patients on hemodialysis in a case-controlled study matching 152 randomly selected non-sevelamer hydrochloride treated Medicare patients from the same dialysis facilities and time period. The main outcomes evaluated were the risk of all-cause hospitalization and per-member per-month (PMPM) Medicare expenditures in the follow-up period., Patients and Methods: Medicare patients were identified from a total of 195 patients who were included in a long-term safety and efficacy clinical trial evaluating sevelamer hydrochloride [Chertow et al. 1999a]. The average serum calcium-phosphorus product as well as lipid profiles improved in the sevelamer hydrochloride treated group during the trial. Sevelamer treated patients were matched with randomly selected Medicare patients for age, gender, race, diabetic status, and geographic location. Comorbid conditions were characterized and sequential Cox regression models were applied with the outcome being risk of first hospitalization in a 17- month follow-up period., Results: Across all four models, the relative risk of hospitalization was 46% to 54% less in the sevelamer hydrochloride treated group, as compared to the case control group (significant at the p-value 0.03 level). Overall, Medicare expenditures for the control patients per-member per-month were US-$4,745, compared to US-$3,368 in the sevelamer hydrochloride treated patients., Conclusion: Sevelamer hydrochloride treated patients had a 50% lower likelihood of hospitalization in the follow-up period after adjustments for the differences in the population. Potential bias may exist between groups because of differences in baseline characteristics that could not be adjusted for within the study design. We feel that to further advance this area, a randomized clinical trial should be performed.

Prior studies on reuse-associated mortality have presented conflicting results and included few adjustments for disease severity or hematocrit levels. To evaluate the impact of patient and provider characteristics on reuse-associated mortality, we developed a period-prevalent model with a 6-month entry period. Five cohorts of Medicare hemodialysis patients surviving from July 1 through December 31 of the entry year (1991, 60,985 patients; 1992, 63,081 patients; 1993, 76,018 patients; 1994, 82,899 patients; 1995, 91,761 patients) were followed up for the next year. Using a basic Cox regression survival model (M-1) including age, sex, race, renal diagnosis, prior end-stage renal disease time, unit age, unit size, water treatment, dialysate, and germicide, results were compared with those using a more inclusive model (M-4) adding dialyzer type (conventional or high efficiency/high flux), unit designation (hospital based or freestanding), unit profit status, comorbidity, disease severity, and hematocrit. The previous association of for-profit units with increased mortality was not present after 1994. Whereas the M-1 analysis showed better survival in reuse units after 1991, the more complete M-4 analysis showed no difference in the risk for mortality between reuse and no-reuse units. We conclude that mortality rates in the United States from 1991 to 1995, when adjusted comprehensively for patient and unit characteristics, were not different in units that practiced reuse and those that did not.

Studies of outcomes associated with dialysis therapies have yielded conflicting results. Bloembergen et al showed that prevalent patients on continuous ambulatory peritoneal dialysis (CAPD) or continuous cycling peritoneal dialysis (CCPD) had a 19% higher mortality risk than hemodialysis patients, and Fenton et al, analyzing Canadian incident patients, found a 27% lower risk. Attempting to reconcile these differences, we evaluated incident Medicare patients (99,048 on hemodialysis, 18,110 on CAPD/CCPD) from 1994 through 1996, following up to June 30, 1997. Patients were followed to transplantation, death, loss to follow-up, 60 days after modality change, or end of the study period. For each 3-month survival period, we used an interval Poisson regression to compare death rates, adjusting for age, gender, race, and primary renal diagnosis. A Cox regression was used to evaluate cause-specific mortality, and proportionality was addressed in both regressions by separating diabetic and nondiabetic patients. The Poisson regressions showed CAPD/CCPD to have outcomes comparable with or significantly better than hemodialysis, although results varied over time. The Cox regression found a lower mortality risk in nondiabetic CAPD/CCPD patients (women younger than 55 years: risk ratio [RR] = 0. 61; Cl, 0.59 to 0.66; women age 55 years or older: RR = 0.87; Cl, 0. 84 to 0.91; men younger than 55 years: RR = 0.72; Cl, 0.67 to 0.77; men age 55 years or older: RR = 0.87; Cl, 0.83 to 0.92) and in diabetic CAPD/CCPD patients younger than 55 (women: RR = 0.88; Cl, 0. 82 to 0.94; men: RR = 0.86; Cl, 0.81 to 0.92). The risk of all-cause death for female diabetics 55 years of age and older, in contrast, was 1.21 (Cl, 1.17 to 1.24) for CAPD/CCPD, and in cause-specific analyses, these patients had a significantly higher risk of infectious death. We conclude that, overall, within the first 2 years of therapy, short-term CAPD/CCPD appears to be associated with superior outcomes compared with hemodialysis. It also appears that patients on the two therapies have different mortality patterns over time, a nonproportionality that makes survival analyses vulnerable to the length of follow-up. Further investigation is needed to evaluate both the potential explanations for these findings and the use of more advanced statistical methods in the analysis of mortality rates associated with these dialytic therapies.

Quantitation of hemodialysis by measuring changes in blood solute concentration requires careful timing when taking the postdialysis blood sample to avoid errors from postdialysis rebound and from recirculation of blood through the access device. It also requires complex mathematical interpretation to account for solute disequilibrium in the patient. To circumvent these problems, hemodialysis can be quantified and its adequacy assessed by direct measurement of the urea removed in the dialysate. Because total dialysate collection is impractical, an automated method was developed for measuring dialysate urea-nitrogen concentrations at frequent intervals during treatment. A multicenter clinical trial of the dialysate monitoring device, the Biostat 1000 (Baxter Healthcare Corporation, McGaw Park, IL) was conducted to validate the measurements of urea removed, the delivered dialysis dose (Kt/V), and net protein catabolism (PCR). The results were compared with a total dialysate collection in each patient. During 29 dialyses in 29 patients from three centers, the paired analysis of urea removed, as estimated by the dialysate monitor compared with the total dialysate collection, showed no significant difference (14.7 +/- 4.7 g versus 14.8 +/- 5.1 g). Similarly, measurements of Kt/V and PCR showed no significant difference (1.30 +/- 0.18 versus 1.28 +/- 0.19, respectively, for Kt/V and 42.3 +/- 15.7 g/day versus 52.2 +/- 17.4 g/day for PCR). When blood-side measurements during the same dialyses were analyzed with a single-compartment, variable-volume model of urea kinetics, Kt/V was consistently overestimated (1.49 +/- 0.29/dialysis, P < 0.001), most likely because of failure to consider urea disequilibrium. Because urea disequilibrium is difficult to quantitate during each treatment, dialysate measurements have obvious advantages. The dialysate monitor eliminated errors from dialysate bacterial contamination, simplified dialysate measurements, and proved to be a reliable method for quantifying and assuring dialysis adequacy.

Dialyzer small-molecule clearance measurements are commonly made to help identify the cause of inadequate dialysis prescriptions, to determine the efficacy of reuse procedures, or to choose between different types of dialyzers. Clearance measurements can be blood-side- or dialysate-side-based. While blood-side clearance measurement is the classical technique, it suffers from several serious flaws that decrease its accuracy. Chief among these are the inability to accurately measure the blood flow rate and the difficulty in accounting for the presence of nonaqueous components in the blood. Using a dialysate-based clearance measurement technique overcomes these problems for most solutes, provided appropriate guidelines are followed. This article reviews the theory behind both blood- and dialysate-side techniques as well as discussing the practical application of that theory to clearance measurement.

The BioStat 1000 is a new device which employs dialysate-based urea kinetics to calculate the dose of dialysis (Kt/V) based on a two-pool model and protein catabolic rate (PCR). Previous methods relying on blood sampling techniques were subject to error and difficult to implement. This paper describes the features of the Biostat and the results of the first clinical validation study with an early prototype. The BioStat was found to compare favorably with the reference method of direct dialysate quantification (mDDQ) which had been modified to obtain a "two-pool" Kt/V. In 31 patients no significant difference was found between mean Kt/V from the mDDQ and the mean Kt/V from the BioStat (1.35 +/- 0.33 versus 1.38 +/- 0.36, respectively). The PCR was also not significantly different (53.4 +/- 18.5 g/day versus 51.8 +/- 16 g/day, respectively). The BioStat was demonstrated to be a convenient method producing reliable results.