Rate of Decline of Kidney Function, Modality Choice, and Survival in Elderly Patients with Advanced Kidney Disease.

AIM: In elderly, dependent patients with advanced chronic kidney disease, dialysis may confer only a small survival advantage over conservative kidney management (CKM). We investigated the role of rate of decline of kidney function on treatment choices and survival. METHODS: We identified a retrospective (1995-2010) cohort of patients aged over 75 years, with progressive kidney impairment and an estimated glomerular filtration rate (eGFR) between 10 and 15 ml/min/1.73 m2. All subsequently chose to be treated by either dialysis or CKM. Patients were followed for a minimum of 3 years. RESULTS: Of 250 patients identified, 92 (37%) opted for dialysis and 158 (63%) for CKM. Mean age was 80.9 ± 4.0 years. eGFR was 13.3 ± 1.4 initially and 8.7 ± 3.0 ml/min/1.73 m2 at follow-up. Both were similar in those on dialysis and CKM pathways. Rate of decline of eGFR was more rapid in those choosing dialysis (0.45 (interquartile range, IQR 0.64) vs. 0.21 (IQR 0.28) ml/min/1.73 m2/month, p < 0.001), and independently predicted choice of CKM. In patients with high comorbidity, choice of dialysis was associated with a non-significant adjusted survival advantage of 5 months. Inclusion in models of time dependent eGFR during follow-up (eGFRtd) - a reflection of the rate of decline of kidney function - showed it to be independently associated with mortality risk in those on the CKM (p < 0.001) but not on the dialysis pathway. CKM pathway patients at the 25th centile of eGFRtd had an adjusted survival of 7 months compared to 63 months for those at the 75th centile. CONCLUSIONS: Rate of decline of kidney function is a determinant of CKM choice in elderly patients and is associated with mortality risk in patients of the CKM pathway. These findings should inform counselling.

Blood pressure levels and mortality risk among hemodialysis patients in the Dialysis Outcomes and Practice Patterns Study.

KDOQI practice guidelines recommend predialysis blood pressure <140/90 mm Hg; however, most prior studies had found elevated mortality with low, not high, systolic blood pressure. This is possibly due to unmeasured confounders affecting systolic blood pressure and mortality. To lessen this bias, we analyzed 24,525 patients by Cox regression models adjusted for patient and facility characteristics. Compared with predialysis systolic blood pressure of 130-159 mm Hg, mortality was 13% higher in facilities with 20% more patients at systolic blood pressure of 110-129 mm Hg and 16% higher in facilities with 20% more patients at systolic blood pressure of ≥160 mm Hg. For patient-level systolic blood pressure, mortality was elevated at low (<130 mm Hg), not high (≥180 mm Hg), systolic blood pressure. For predialysis diastolic blood pressure, mortality was lowest at 60-99 mm Hg, a wide range implying less chance to improve outcomes. Higher mortality at systolic blood pressure of <130 mm Hg is consistent with prior studies and may be due to excessive blood pressure lowering during dialysis. The lowest risk facility systolic blood pressure of 130-159 mm Hg indicates this range may be optimal, but may have been influenced by unmeasured facility practices. While additional study is needed, our findings contrast with KDOQI blood pressure targets, and provide guidance on optimal blood pressure range in the absence of definitive clinical trial data.

Survival of elderly patients with stage 5 CKD: comparison of conservative management and renal replacement therapy.

BACKGROUND: Elderly patients with end-stage renal disease and severe extra-renal comorbidity have a poor prognosis on renal replacement therapy (RRT) and may opt to be managed conservatively (CM). Information on the survival of patients on this mode of therapy is limited. METHODS: We studied survival in a large cohort of CM patients in comparison to patients who received RRT. RESULTS: Over an 18-year period, we studied 844 patients, 689 (82%) of whom had been treated by RRT and 155 (18%) were CM. CM patients were older and a greater proportion had high comorbidity. Median survival from entry into stage 5 chronic kidney disease was less in CM than in RRT (21.2 vs 67.1 months: P < 0.001). However, in patients aged > 75 years when corrected for age, high comorbidity and diabetes, the survival advantage from RRT was ~ 4 months, which was not statistically significant. Increasing age, the presence of high comorbidity and the presence of diabetes were independent determinants of poorer survival in RRT patients. In CM patients, however, age > 75 years and female gender independently predicted better survival. CONCLUSIONS: In patients aged > 75 years with high extra-renal comorbidity, the survival advantage conferred by RRT over CM is likely to be small. Age > 75 years and female gender predicted better survival in CM patients. The reasons for this are unclear.

Long-term outcomes in online hemodiafiltration and high-flux hemodialysis: a comparative analysis.

BACKGROUND AND OBJECTIVES: Theoretical advantages exist of online hemodiafiltration (HDF) over high-flux hemodialysis (HD), but outcome data are scarce. Our objective was to compare outcomes between these modalities. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We studied 858 incident patients in our incremental high-flux HD and online HDF program during an 18-yr period. We compared outcomes, including survival, in those who were treated predominantly with HDF (>50% sessions) and those with high-flux HD. Survival comparisons used a Cox model taking into account the time-varying proportion of time spent on HDF. All data were prospectively collected. RESULTS: A total of 152,043 sessions were delivered as HDF and 291,222 as high-flux HD. A total of 232 (27%) patients were treated predominantly with HDF and 626 (73%) with high-flux HD. Total Kt/V, serum albumin, erythropoietin resistance index, and BP were similar in both groups up to 5 yr after HD initiation. Intradialytic hypotension was less frequent in the predominant HDF group. Predominant HDF treatment was associated with a reduced risk for death after correction for confounding variables. In a second Cox model, proportion of time spent on HDF predicted survival, such that patients who were treated solely by HDF would have a hazard for death of 0.66 compared with those who solely used high-flux HD. CONCLUSIONS: We found no benefits of HDF over high-flux HD with respect to anemia management, nutrition, mineral metabolism, and BP control. The mortality benefit associated with HDF requires confirmation in large randomized, controlled trials. These data may contribute to their design.

Residual renal function improves outcome in incremental haemodialysis despite reduced dialysis dose.

BACKGROUND AND METHODS: The importance of residual renal function is well recognized in peritoneal dialysis but its role in haemodialysis (HD) has received much less attention. We studied 650 incident patients in our incremental high-flux HD programme over a 15-year period. Target total Kt/V urea (dialysis plus residual renal) was 1.2 per session and monitored monthly. Renal urea clearance (KRU) was estimated 1-3 monthly. RESULTS: KRU declined during the first 5 years of HD from 3.1 +/- 1.9 at 3 months to 0.9 +/- 1.2 ml/min/1.73 m(2) at 5 years. The percentage of patients with KRU >or= 1 ml/min at these time points was 85% and 31%, respectively. Patients with KRU >or= 1 ml/min had a significantly lower mean creatinine (all time points), ultrafiltration requirement (all time points) and serum potassium (6, 12, 36 and 48 months). Nutritional parameters were also significantly better in respect to nPCR and serum albumin (6, 12, 24 and 36 months). Patients with KRU >or= 1 ml/min had significantly lower erythropoietin requirements and erythropoietin resistance indices (12, 24, 36 and 48 months). Mortality was significantly lower in patients with a KRU >or= 1 at 6, 12 and 24 months after HD initiation, this benefit being maintained after correcting for albumin, age, comorbidities, HDF use and renal diagnosis. Our unique finding was that these benefits occurred despite those with KRU >or= 1 ml/min having a significantly lower dialysis Kt/V at all time points. CONCLUSION: The associations demonstrated suggest that residual renal function contributes significantly to outcome in HD patients and that efforts to preserve it are warranted. Comparative outcome studies should be controlled for residual renal function.

The survival advantage for haemodialysis patients taking vitamin D is questioned: findings from the Dialysis Outcomes and Practice Patterns Study.

BACKGROUND: Retrospective studies of haemodialysis patients from large dialysis organizations in the United States have indicated that intravenous vitamin D may be associated with a survival benefit. However, patients prescribed vitamin D are generally healthier than those who are not, suggesting that treatment by indication may have biased previous findings. Additionally, no survival benefit associated with vitamin D has been shown in a recent meta-analysis in CKD patients. Because treatment-by-indication bias due to both measured and unmeasured confounders cannot be completely accounted for in standard regression or marginal structural models (MSMs), this study evaluates the association between vitamin D and mortality among participants in the Dialysis Outcomes and Practice Patterns Study (DOPPS) using standard regression and MSMs with an expanded set of covariates, as well as by instrumental variable models to minimize potential bias due to unmeasured confounders. METHODS: Data from 38 066 DOPPS participants from 12 countries between 1996 and 2007 were analysed. Mortality risk was assessed using standard baseline and time-varying Cox regression models, adjusted for demographics and detailed comorbidities, and MSMs. In models similar to instrumental variable analysis, the facility percentage of patients prescribed vitamin D, adjusted for the patient case mix, was used to predict patient-level mortality. RESULTS: Vitamin D prescription was significantly higher in the USA compared to other countries. On average, patients prescribed vitamin D had fewer comorbidities compared to those who were not. Vitamin D therapy was associated with lower mortality in adjusted time-varying standard regression models [relative ratio (RR) = 0.92 (95% confidence interval: 0.87-0.96)] and baseline MSMs [RR = 0.84 (0.78-0.98)] and time-varying MSMs [RR = 0.78 (0.73-0.84)]. No significant differences in mortality were observed in adjusted baseline standard regression models for patients with or without vitamin D prescription [RR = 0.98 (0.93-1.02)] or for patients in facility practices where vitamin D prescription was more frequent [RR for facilities in 75th versus 25th percentile of vitamin D prescription = 0.99 (0.94-1.04)]. CONCLUSIONS: Vitamin D was associated with a survival benefit in models prone to bias due to unmeasured confounding. In agreement with a meta-analysis of randomized controlled studies, no difference in mortality was observed in instrumental variable models that tend to be more independent of unmeasured confounding. These findings indicate that a randomized controlled trial of vitamin D and clinical outcomes in haemodialysis patients are needed and can be ethically conducted.

Factors associated with health-related quality of life among hemodialysis patients in the DOPPS.

OBJECTIVE: To identify modifiable factors associated with health-related quality of life (HRQOL) among chronic hemodialysis patients. METHODS: Analysis of baseline data of 9,526 hemodialysis patients from seven countries enrolled in phase I of the Dialysis Outcomes and Practice Patterns Study (DOPPS). Using the Kidney Disease Quality of Life Short Form (KDQOL-SF(TM)), we determined scores for 8 generic scale summaries derived from these scales, i.e., the physical component summary [PCS] and mental component summary [MCS], and 11 kidney disease- targeted scales. Regression models were used to adjust for differences in comorbidities and sociodemographic and treatment factors. The Benjamini-Hochberg procedure was used to correct P-values for multiple comparisons. RESULTS: Unemployment and psychiatric disease were independently and significantly associated with lower scores for all generic and several kidney disease-targeted HRQOL measures. Several other comorbidities, lower educational level, lower income, and hypoalbuminemia were also independently and significantly associated with lower scores of PCS and/or MCS and several generic and kidney disease-targeted scales. Hemodialysis by catheter was associated with significantly lower PCS scores, partially explained by the correlation with covariates. CONCLUSION: Associations of poorer HRQOL with preventable or controllable factors support a greater focus on psychosocial and medical interventions to improve the well-being of hemodialysis patients.

International differences in dialysis mortality reflect background general population atherosclerotic cardiovascular mortality.

Existing national, racial, and ethnic differences in dialysis patient mortality rates largely are unexplained. This study aimed to test the hypothesis that mortality rates related to atherosclerotic cardiovascular disease (ASCVD) in dialysis populations (DP) and in the background general populations (GP) are correlated. In a cross-sectional, multinational study, all-cause and ASCVD mortality rates were compared between GP and DP using the most recent data from the World Health Organization mortality database (67 countries; 1,571,852,000 population) and from national renal registries (26 countries; 623,900 population). Across GP of 67 countries (14,082,146 deaths), all-cause mortality rates (median 8.88 per 1000 population; range 1.93 to 15.40) were strongly related to ASCVD mortality rates (median 3.21; range 0.53 to 8.69), with Eastern European countries clustering in the upper and Southeast and East Asian countries in the lower rate ranges. Across DP (103,432 deaths), mortality rates from all causes (median 166.20; range 54.47 to 268.80) and from ASCVD (median 63.39 per 1000 population; range 21.52 to 162.40) were higher and strongly correlated. ASCVD mortality rates in DP and in the GP were significantly correlated; the relationship became even stronger after adjustment for age (R(2) = 0.56, P < 0.0001). A substantial portion of the variability in mortality rates that were observed across DP worldwide is attributable to the variability in background ASCVD mortality rates in the respective GP. Genetic and environmental factors may underlie these differences.

Large variations in prescriptions of gastrointestinal medications in hemodialysis patients on three continents: the Dialysis Outcomes and Practice Patterns Study (DOPPS).

Little is known about proton pump inhibitor (PPI) or H(2) receptor antagonist (HA) prescription patterns or regarding use of predictors in hemodialysis patients. Proton pump inhibitor and HA prescribing patterns were investigated in 8628 hemodialysis patients from seven countries enrolled in the prospective, observational Dialysis Outcomes and Practice Patterns Study. Logistic regression examined predictors associated with PPI and HA use, adjusting for age, sex, country, time with end-stage renal disease, medications, 14 comorbid conditions, and the association between the number of comorbid conditions and the prescription of gastrointestinal (GI) medications. In a cross-section from February 1, 2000, 3.4% to 36.9% of patients received an HA and 0.8% to 26.9% took a PPI, depending upon the country. From 1996 to 2001, the prescription of HAs declined while PPI use increased. Facility use of HAs and PPIs ranged from 0% to 94% of patients. H2 receptor antagonist or PPI use was significantly and independently associated with age, narcotic use, corticosteroids, acetaminophen, nonsteroidal anti-inflammatory drugs, tricyclic antidepressants, selective serotonin reuptake inhibitors, coronary artery disease history, cardiovascular diseases other than hypertension or congestive heart failure, peripheral vascular disease, pulmonary disease, and GI bleed. Proton pump inhibitors or HAs were more likely to be prescribed in Italy, Spain, and the United Kingdom than in the United States. The odds of PPI prescription increased if serum phosphorus <5.5 mEq/L or serum albumin <3.5 g/dL. Prescription of GI medications was associated with many comorbidities and use of several medications. Extreme variability of prescription patterns suggests that there is no standard approach in treatment practices.

Selected lessons learned from the Dialysis Outcomes and Practice Patterns Study (DOPPS).

The Dialysis Outcomes and Practice Patterns Study (DOPPS) is a prospective, observational study of the relationships between hemodialysis (HD) patient outcomes and HD treatment practices. The DOPPS began in 1996 in the United States, expanding to France, Germany, Italy, Japan, Spain, and the United Kingdom in 1998-1999, and then to Australia, Belgium, Canada, New Zealand, and Sweden in 2002. More than 300 dialysis units have participated in the DOPPS since 1996, with mortality data collected from nearly 90,000HD patients and detailed longitudinal data from nearly 30,000 HD patients. Large sample size and the large treatment practice variation observed in the DOPPS--given its international scope of participation--provide strong statistical power to investigate many different HD practices. Furthermore, the detailed patient data collected in the DOPPS allow relationships to account for differences in a large number of patient characteristics. More than 55 papers have been published from the DOPPS; here we provide a summary of selected DOPPS findings regarding nutrition, mineral metabolism, anemia management, vascular access, depression, and use of multivitamins and statins.

Effect of ultrafiltration on thermal variables, skin temperature, skin blood flow, and energy expenditure during ultrapure hemodialysis.

The cause of the increase in core temperature (CT) during hemodialysis (HD) is still under debate. It has been suggested that peripheral vasoconstriction as a result of hypovolemia, leading to a reduced dissipation of heat from the skin, is the main cause of this increase in CT. If so, then it would be expected that extracorporeal heat flow (Jex) needed to maintain a stable CT (isothermic; T-control = 0, no change in CT) is largely different between body temperature control HD combined with ultrafiltration (UF) and body temperature control HD without UF (isovolemic). Consequently, significant differences in DeltaCT would be expected between isovolemic HD and HD combined with UF at zero Jex (thermoneutral; E-control = 0, no supply or removal of thermal energy to and from the extracorporeal circulation). During the latter treatment, the CT is expected to increase. In this study, changes in thermal variables (CT and Jex), skin blood flow, energy expenditure, and cytokines (TNF-alpha, IL-1 receptor antagonist, and IL-6) were compared in 13 patients, each undergoing body temperature control (T-control = 0) HD without and with UF and energy-neutral (E-control = 0) HD without and with UF. CT increased equally during energy-neutral treatments, with (0.32 +/- 0.16 degrees C; P = 0.000) and without (0.27 +/- 0.29 degrees C; P = 0.006) UF. In body temperature control treatments, the relationship between Jex and UF tended to be significant (r = -0.51; P = 0.07); however, there was no significant difference in cooling requirements regardless of whether treatments were done without (-17.9 +/- 9.3W) or with UF (-17.8 +/- 13.27W). Changes in energy expenditure did not differ among the four treatment modes. There were no significant differences in pre- and postdialysis levels of cytokines within or between treatments. Although fluid removal has an effect on thermal variables, no single mechanism seems to be responsible for the increased heat accumulation during HD.

Patterns of hepatitis C prevalence and seroconversion in hemodialysis units from three continents: the DOPPS.

BACKGROUND: Hepatitis C virus (HCV) remains a problem within hemodialysis units. This study measures HCV prevalence and seroconversion rates across seven countries and investigates associations with facility-level practice patterns. METHODS: The study sample was from the Dialysis Outcomes and Practice Patterns Study (DOPPS), a prospective, observational study of adult hemodialysis patients randomly selected from 308 representative dialysis facilities in France, Germany, Italy, Japan, Spain, the United Kingdom, and the United States. Logistic regression was used to model odds of HCV prevalence, and Cox regression was used to model time from study entry to HCV seroconversion. RESULTS: Mean HCV facility prevalence was 13.5% and varied among countries from 2.6% to 22.9%. Increased HCV prevalence was associated with longer time on dialysis, male gender, black race, diabetes, hepatitis B (HBV) infection, prior renal transplant, and alcohol or substance abuse in the previous 12 months. Approximately half of the facilities (55.6%) had no seroconversions during the study period. HCV seroconversion was associated with longer time on dialysis, human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS), HBV infection, and recurrent cellulitis or gangrene. An increase in highly trained staff was associated with lower HCV prevalence (OR = 0.93 per 10% increase, P= 0.003) and risk of seroconversion (RR = 0.92, P= 0.07). Seroconversion was associated with an increase in facility HCV prevalence (RR = 1.36, P < 0.0001), but not with isolation of HCV-infected patients (RR = 1.01, P= 0.99). CONCLUSION: There are differences in HCV prevalence and rate of seroconversion at the country and the hemodialysis facility level. The observed variation suggests opportunities for improved HCV outcomes.

Erythropoeitin dose variation in different facilities in different countries and its relationship to drug resistance.

BACKGROUND: The correction of anemia using erythropoeitin (EPO) is accorded high priority in the management of patients undergoing hemodialysis (HD). Target hemoglobin (Hb) levels have been established in many countries. Following an observation that the mean facility EPO dose in a chain of facilities in the United States varied by more than two-fold, an examination of the practice of anemia correction in other settings was carried out. METHODS: We reviewed demographic and laboratory parameters in prevalent HD patients in 50 United States facilities and in a single HD facility in Vicenza, Italy. The mean EPO dose profile of the United States facilities was compared with the profiles in 10 facilities in the eastern United Kingdom (UKER) and in 20 facilities reporting to the United Kingdom Renal Registry (UKRR). Analysis of the factors that correlate with EPO resistance was carried out using the United States and Italian data. RESULTS: The average EPO doses, by facility, in the 51 United States, the 10 UKER, and the 19 UKRR facilities were 19,569, 8,416, and 7,992 international units per week (IU/wk), respectively. While examination of the UKRR revealed a similar degree of inter-facility variation (2.6-fold), much larger doses of EPO were being administered in the United States patients, particularly in the low Hb group. Multivariate analysis of the United States data suggested that factors related to inflammation, including low albumin, the use of tunneled catheters for vascular access, and low protein catabolic rate (enPCR) correlated with low Hb and relative EPO resistance. CONCLUSION: Despite similar guidelines for anemia management, significant differences in practice are observed. While there seems to be a reluctance to administer large EPO doses to individual patients in Europe, this does not seem to apply in the United States, where more EPO is given. EPO resistance seems relative rather than absolute in many patients, allowing some to respond to the higher doses.

Vascular access use in Europe and the United States: results from the DOPPS.

BACKGROUND: A direct broad-based comparison of vascular access use and survival in Europe (EUR) and the United States (US) has not been performed previously. Case series reports suggest that vascular access practices differ substantially in the US and EUR. We report on a representative study (DOPPS) which has used the same data collection protocol for> 6400 hemodialysis (HD) patients to compare vascular access use at 145 US dialysis units and 101 units in five EUR countries (France, Germany, Italy, Spain, and the United Kingdom). METHODS: Logistic analysis evaluated factors associated with native arteriovenous fistula (AVF) versus graft use or permanent access versus catheter use for prevalent and incident HD patients. Times to failure for AVF and graft were analyzed using Cox proportional hazards regression. RESULTS: AVF was used by 80% of EUR and 24% of US prevalent patients, and was significantly associated with younger age, male gender, lower body mass index, non-diabetic status, lack of peripheral vascular disease, and no angina. After adjusting for these factors, AVF versus graft use was still much higher in EUR than US (AOR=21, P < 0.0001). AVF use within facilities varied from 0 to 87% (median 21%) in the US, and 39 to 100% (median 83%) in EUR. For patients who were new to HD, access use was: 66% AVF in EUR versus 15% in US (AOR=39, P < 0.0001), 31% catheters in EUR vs. 60% in US, and 2% grafts in EUR vs. 24% in US. In addition, 25% of EUR and 46% of US incident patients did not have a permanent access placed prior to starting HD. In EUR, 84% of new HD patients had seen a nephrologist for> 30 days prior to ESRD compared with 74% in the US (P < 0.0001); pre-ESRD care was associated with increased odds of AVF versus graft use (AOR=1.9, P=0.01). New HD patients had a 1.8-fold greater odds (P=0.002) of starting HD with a permanent access if a facility's typical time from referral to access placement was < or =2 weeks. AVF use when compared to grafts was substantially lower (AOR=0.61, P=0.04) when surgery trainees assisted or performed access placements. When used as a patient's first access, AVF survival was superior to grafts regarding time to first failure (RR=0.53, P=0.0002), and AVF survival was longer in EUR compared with the US (RR=0.49, P=0.0005). AVF and grafts each displayed better survival if used when initiating HD compared with being used after patients began dialysis with a catheter. CONCLUSION: Large differences in vascular access use exist between EUR and the US, even after adjustment for patient characteristics. The results strongly suggest that a facility's preferences and approaches to vascular access practice are major determinants of vascular access use.

Membrane flux not biocompatibility determines beta-2-microglobulin levels in hemodialysis patients.

BACKGROUND: Serum beta(2)-microglobulin (beta(2)M) levels are important in dialysis-related amyloid deposition but can be influenced by dialysis technique. METHODS: We measured beta(2)M levels in 3 centres using different dialysis regimes. Centre 1 (73 patients) used high-flux biocompatible, centre 2 (72 patients) low-flux biocompatible and centre 3 (142 patients) cuprophane dialysers. RESULTS: beta(2)M levels were lower with high-flux biocompatible than with low-flux biocompatible or cuprophane dialysis (22.3 +/- 5.4 vs. 43.4 +/-13.7 and 37.6 +/-13.1 mg/l, respectively; p < 0.001). Levels were higher with low-flux biocompatible than with cuprophane dialysis (p < 0.001), but not if patients dialysed over 10 years were excluded. With low-flux biocompatible (47.4 +/- 9.8 vs. 38.7 +/- 15.2 mg/l; p < 0.01) and cuprophane dialysis (43.4 +/- 8.2 vs. 36.7 +/- 13.0 mg/l; p < 0.02), beta(2)M levels were higher in patients dialysed over 5 years than in those dialysed less. Despite beta(2)M levels increasing as residual renal function declined, there was no similar rise with high-flux biocompatible dialysis. CONCLUSIONS: Techniques allowing significant convection maintain lower beta(2)M levels over many years. Membrane flux, not biocompatibility, is the main determinant of beta(2)M levels in routine practice.

Identical decline of residual renal function in high-flux biocompatible hemodialysis and CAPD.

BACKGROUND: Patients on conventional hemodialysis lose residual renal function more rapidly than patients on continuous ambulatory peritoneal dialysis (CAPD). The effect of dialysis using synthetic membranes and ultrapure water is less clear. METHODS: The decline of urea clearance was compared in a cohort of 475 incident end-stage renal failure patients who received treatment with CAPD (N=175) or hemodialysis (HD) utilizing high-flux polysulphone membranes, ultrapure water, and bicarbonate as the buffer (N=300). RESULTS: CAPD patients were significantly younger, fitter (lower comorbidity severity score), less dependent (higher Karnofsky performance score) and less likely to have presented late than HD patients. There was no difference in the mean urea clearance in each group at dialysis initiation, or at any 6-month time point during the ensuing 48 months. This was true even after exclusion of patients who had died in the first year after initiation, those transferred to another dialysis modality, or those who had been transplanted. Only age and chronic interstitial disease predicted retention of urea clearance at one year. The rate of decline of urea clearance was similar in pre- and post-dialysis initiation phases, though there may have been a step-decline of about 2 mL/min at initiation, which requires further investigation. CONCLUSIONS: In hemodialysis using high-flux biocompatible membranes and ultrapure water, residual renal function declines at a rate indistinguishable from that in CAPD. This may have important implications, since preservation of residual renal function has major benefits and is a valid therapeutic goal.