Decline Of Residual Renal Function Research Articles

Preservation of residual renal function and factors affecting its decline in patients on peritoneal dialysis.

The decline of residual renal function (RRF) in peritoneal dialysis (PD) patients was analysed and assessed, and risk factors affecting its decline were identified. Residual glomerular filtration rate (GFR) was calculated from averaging the urea and creatinine clearance by 24-h urine collection, and peritoneal solute removal was evaluated by creatinine clearance calculated from 24-h effluent collection. Both GFR and peritoneal solute removal were chronologically examined in 34 PD patients from the time of initiation, and risk factors associated with rapid GFR decline were investigated. The RRF contributed to 43.1 +/- 17.6% of total (peritoneal and renal) weekly creatinine clearance at 1 month after initiation of PD. Residual GFR, however, declined continuously with time (-0.19 +/- 0.14 mL/min per month), and the reduction rate was high with a higher GFR, higher normalized dietary protein intake, higher urine volume and higher urine protein excretion at the initiation of PD. Other factors related to the rapid decline of GFR were: being older than 60 years of age, automated peritoneal dialysis (APD) rather than continuous ambulatory peritoneal dialysis, mean blood pressure higher than 110 mmHg, and serum human atrial natriuretic peptide level higher being than 60 pg/dL. These data suggest that while RRF plays an important role in the removal of uraemic solute in PD patients, they show a significant decrease over 2 years. The factors related to the rapid decline of GFR corresponded to older age, modality of PD (APD), higher GFR and higher amount of urine protein at initiation, higher dietary protein intake, and inadequate control of hypertension and body fluid volume.

Rapid Decline of Residual Renal Function in Patients with Late Renal Transplant Failure who are Re-Treated with CAPD

Rapid Decline of Residual Renal Function in Patients with Late Renal Transplant Failure who are Re-Treated with CAPD

Predictors of Decline of Residual Renal Function in New Peritoneal Dialysis Patients

The aim of this study was to prospectively evaluate the risk factors for decline of residual renal function (RRF) in an incident peritoneal dialysis (PD) population. Prospective observational study of an incident PD cohort at a single center. Tertiary-care institutional dialysis center. The study included 146 consecutive patients commencing PD at the Princess Alexandra Hospital between 1 August 1995 and 1 July 2001 (mean age 54.8 +/- 1.4 years, 42% male, 34% diabetic). Patients with failed renal transplants (n = 26) were excluded. Timed urine collections (n = 642) were performed initially and at 6-month intervals thereafter to measure RRF. The development of anuria was also prospectively recorded. The mean (+/- SD) follow-up period was 20.5 +/- 14.8 months. The median slope of RRF decline was -0.05 mL/minute/month/1.73 m2. Using binary logistic regression, it was shown that the 50% of patients with more rapid RRF loss (< -0.05 mL/min/month/1.73 m2) were more likely to have had a higher initial RRF at commencement of PD [adjusted odds ratio (AOR) 1.83, 95% confidence interval (CI) 1.39-2.40] and a higher baseline dialysate/ plasma creatinine ratio at 4 hours (D/P creat; AOR 44.6, 95% CI 1.05-1900). On multivariate Cox proportional hazards model analysis, time from commencement of PD to development of anuria was independently predicted by baseline RRF [adjusted hazard ratio (HR) 0.81, 95% CI 0.60-0.81], D/P creat (HR 2.87, 95% CI 2.06-82.3), body surface area (HR 6.23, 95% CI 1.53-25.5), dietary protein intake (HR 2.87, 95% CI 1.06-7.78), and diabetes mellitus (HR 1.65, 95% CI 1.00-2.72). Decline of RRF was independent of age, gender, dialysis modality, urgency of initiation of dialysis, smoking, vascular disease, blood pressure, medications (including angiotensin-converting enzyme inhibitors), duration of follow-up, and peritonitis rate. The results of this study suggest that high baseline RRF and high D/P creat ratio are risk factors for rapid loss of RRF. Moreover, a shorter time to the onset of anuria is independently predicted by low baseline RRF, increased body surface area, high dietary protein intake, and diabetes mellitus. Such at-risk patients should be closely monitored for early signs of inadequate dialysis.

Empirical aminoglycosides for peritonitis do not affect residual renal function

Background: Aminoglycosides have been proven to be an efficacious treatment for peritonitis in peritoneal dialysis patients for many years. Consequently, they have been recommended in previous guidelines for the empirical treatment of peritonitis. However, with the increasing emphasis on preserving residual renal function (RRF), there has been concern about the nephrotoxic potential of these compounds. The 2000 International Society of Peritoneal Dialysis (ISPD) guidelines recommended that aminoglycosides not be used in patients with RRF, and that ceftazidime be used instead. In 1997, in response to the 1996 ISPD guidelines, we changed our peritonitis regimen from vancomycin and ciprofloxacin to cefazolin and gentamicin. The aim of this study is to compare the change in renal function occurring after treatment of peritonitis with and without gentamicin. Methods: Using 6-monthly urine and dialysis clearance measurements, preperitonitis and postperitonitis RRF (mean of 24-hour urea and creatinine clearance) were determined for 70 peritonitis episodes treated with the aminoglycoside-based regimen (group A), 61 episodes treated without aminoglycosides (group B), and 74 control patients without peritonitis (group C). Results: Group A had mean declines in estimated glomerular filtration rate and urine output of −0.08 ± 0.50 mL/min/mon and −8.82 ± 88.09 mL/24 h/mon compared with −0.17 ± 0.27 mL/min/mon and −34.68 ± 69.58 mL/24 h/mon in group B and −0.20 ± 0.39 mL/min/mon and −14.61 ± 77.33 mL/24 h/mon in group C, respectively. There were no significant differences between groups. Conclusion: In our patients, there was no evidence of an accelerated decline in RRF when using an empirical regimen containing aminoglycosides for peritonitis. Because there are few data to contradict this finding, we recommend the continued use of these drugs in peritonitis regimens, even in patients with significant RRF. Am J Kidney Dis 41:670-675. © 2003 by the National Kidney Foundation, Inc.

The Decline in Residual Renal Function in Hemodialysis Is Slow and Age Dependent

Persons on peritoneal dialysis and hemodialysis with preserved residual renal function experience lower mortality rates than those without. Previous studies have shown slower rates of decline of residual renal function for peritoneal dialysis (PD)(2 to 3% decrease/month), compared with hemodialysis (HD)(6 to 7% decrease/month). However, our clinical observations suggested a lower rate of decline in hemodialysis patients. We evaluated data in 174 hemodialysis patients cared for from January 2000 through October 2001. Eighty-seven (50%) patients had at least two timed quarterly urine collections to estimate the rate of change of residual renal function over time (urea clearance, or KrU). All patients underwent thrice-weekly hemodialysis using polysulfone dialyzers with formaldehyde reprocessing. The rate of decline of residual renal function and the effect of KrU on laboratory variables were estimated using a random effects (MIXED) model, adjusting for the effects of age, sex, race, diabetes, and dialysis vintage. The mean KrU at baseline was 3.5 mL/min. Men (P < 0.001) and persons of shorter vintage (P < 0.0001) had more residual renal function at baseline. The estimated rate of decline of residual renal function was - 0.07 mL/min/month (- 1.9% decrease/month). The rate of decline in residual renal function was unaffected by sex, race, diabetes, or vintage, although the rate of decline was significantly attenuated among older individuals (age x time interaction, P = 0.01). Serum phosphorus (P = 0.03) and the calcium x phosphorus product (P = 0.009) increased over time and were influenced by the level of residual renal function (P = 0.06 and P = 0.006, respectively). Residual renal function did not influence the rate of change of other laboratory variables. In an ethnically diverse cohort of hemodialysis patients, the rate of decline of residual renal function was relatively slow and age dependent, as well as consistent with values others have reported for patients on peritoneal dialysis. Universal use of biocompatible dialyzers and bicarbonate dialysate may have contributed to differences discussed in prior reports. Residual renal function attenuated the increase in calcium-phosphorus product over time. A better understanding of the determinants of the rate of decline in residual renal function, and the specific benefits afforded to patients via maintenance of residual renal function, would help to inform the debates on timing of initiation and various dosing strategies in hemodialysis.

Predictors of the rate of decline of residual renal function in incident dialysis patients

Residual renal function (RRF) influences morbidity, mortality and quality of life in chronic dialysis patients. Few studies have been published on risk factors for loss of RRF in dialysis patients. These studies were either retrospective, performed in a small number of patients, or estimated GFR without a urine collection. We analyzed the decline rates of residual GFR (rGFR) prospectively in 522 incident HD and PD patients who had structured follow-up assessments. GFR was measured as the mean of urea and creatinine clearance, calculated from urine collections. The initial value was obtained 0 to 4 weeks before the start of dialysis. The measurements were repeated 3, 6, and 12 months after the start of dialysis treatment. After logarithmic transformation, differences in rGFR changes over time were analyzed using repeated measurement analysis of variance. Baseline factors that were negatively associated with rGFR at 12 months were a higher diastolic blood pressure (P < 0.001) and a higher urinary protein loss (P < 0.001). Primary kidney disease did not affect rGFR. Averaged over time, PD patients had a higher rGFR (P < 0.001) than HD patients. This relative difference increased over time (P = 0.04). Investigation of possible effects of the dialysis procedure on the decline rate between 0 and three months showed that dialysis hypotension (P = 0.02) contributed to the decline in HD and the presence of episodes with dehydration contributed in PD (P = 0.004). rGFR is better maintained in PD patients than in HD patients. The associated factors such as a higher diastolic blood pressure, proteinuria, dialysis hypotension and dehydration can either be treated or avoided.

Quantifying comorbidity in peritoneal dialysis patients and its relationship to other predictors of survival.

Comorbidity is the single most important determinant of outcome in patients on renal replacement therapy. The aims of this study were to evaluate a semi-quantitative approach to comorbidity scoring in predicting survival of patients commencing peritoneal dialysis (PD), and to establish the interaction between this and other known predictors of patient outcome, in particular membrane function, residual renal function (RRF) and plasma albumin. Comorbidity was recorded in a prospective, single centre cohort study of 303 patients commencing on PD. Using seven disease domains, chosen to reflect the dominance of cardiovascular morbidity in the end-stage renal failure population, comorbidity was graded as '0' when absent, '1' when one or two, and '2' when three or more conditions were present. The Wright comorbidity index, which includes age within the scoring method, was also evaluated. RRF, plasma albumin and peritoneal solute transport were measured every 6 months. Patients were censored at death. Median survival according to grade of comorbidity was 105, 42 and 29 months, respectively (P<0.0001), with good separation of the actuarial survival curves. Using Cox regression, the addition of age and the grade of comorbidity to Kt/V(urea), solute transport and plasma albumin increased the predictive power of the model. All were independent predictors of outcome with the exception of albumin. The Wright comorbidity index also enhanced the Cox model, although was not as powerful as when age and comorbidity were considered independently. At baseline, RRF was not different according to comorbidity unless diabetes was considered separately. Diabetics started with higher RRF, but after 6 months on PD this was the same as non-diabetic patients. Otherwise, initial rate of decline of RRF was similar across the comorbid grades, although the impact of higher drop-out due to earlier loss in patients with more comorbidity may have disguised earlier loss in these patients. Peritoneal solute transport tended to be higher in patients with increased comorbidity at baseline, chi(2) 13.8, P=0.032, and this was sustained with time on treatment. Comorbidity has a quantitative effect on survival that is independent of age, RRF and membrane function in PD patients. Comorbidity also appears to be associated with increased solute transport at the start of treatment, which is sustained. With the exception of diabetes, grade of comorbidity does not have a profound effect on loss of RRF.

Peritoneal Dialysis Retardation of Progression of Advanced Renal Failure

The rate of decline of residual renal function is slower in peritoneal dialysis (PD) than in hemodialysis. However, it is unclear which and whether either of the two techniques modifies the natural course of renal failure. We tested whether PD influences the natural course of the progression of chronic renal failure in humans. Retrospective review of clinical charts. Tertiary-care center. Fourteen patients were selected from the 36 patients that were treated with PD in our center from January 1997 to June 2000, applying the following criteria: predialysis follow-up longer than 12 months, renal creatinine clearance 20 mL/minute or more at the start of predialysis follow-up, follow-up while on PD longer than 6 months, and renal creatinine clearance above 0 mL/minute at the start of PD. Residual renal function calculated as renal creatinine clearance obtained from 24-hour urine samples. A lower mean rate of decline of residual renal function was observed during PD than during the predialysis period (-0.06 +/- 0.16 vs -0.94 +/- 0.74 mL/min/month, p < 0.0005). The rate of decline in renal creatinine clearance was faster in every patient during the predialysis period than during his or her time on PD. These preliminary data support the hypothesis that PD may contribute to the slowing of the natural progression of renal disease in humans, as it does in rodents. Prospective studies involving a larger number of patients are needed to settle the question.

Possible factors contributing to similar peritoneal dialysis outcome in patients over 60 years of age and the younger ones.

The aim of studies was a comparison of dialysis adequacy, nutritional parameters, results of the peritoneal equilibration test (PET) and selected standard clinical and laboratory data in peritoneal dialysis (PD) patients with different age, but comparable PD duration and outcome. Two groups of patients were examined: group I (n = 21, 9 F, 12 M) - age 67.7 +/- 4.5 yrs, PD duration 20.1 +/- 12.1 months; group II (n = 21, 9 F, 12 M) - age 42.8 +/- 9.1 yrs, PD duration 20.7 +/- 12.1 months. Parameters of PD adequacy, results of PET, markers of nutrition and standard laboratory measures were determined every 3 months to the end of PD treatment. First obtained values, mean values representing the entire PD course and last values obtained before the end of PD therapy were compared in group I and II. Differences in results obtained at the beginning and at the end of PD therapy were also compared in each group. At the beginning of PD therapy the older patients showed higher total fat mass (TFM) expressed as % of total body mass (TBM), lower lean body mass (LBM), lower serum levels of iron, phosphorus and creatinine as well as lower transferrin saturation. When mean values representing the entire PD course were compared, the older patients showed higher TFM as % of TBM and serum ferritin level, whereas lower values were observed for diastolic blood pressure (DBP), LBM, serum creatinine, phosphorus and iron. At the end of PD therapy TFM as % of TBM and serum ferritin level remained higher in older patients as well as lower both DBP and LBM were maintained. Additionally, serum cholesterol level and residual renal function (RRF) became at the end of PD treatment higher in the older individuals compared to the younger ones. The difference in RRF between the two groups was caused by the decline in RRF in the younger patients with relatively stable values of RRF in the older ones. Nutritional parameters improved in the course of PD only in the younger group. In conclusion, the older patients reach similar PD outcome parameters compared to the younger ones while they show higher TFM as % of TBM, stable RRF and more satisfactory DBP. However, elderly patients show a greater progress in the deterioration of indices of both inflammation and atherosclerosis and therefore are not able to improve nutritional parameters.

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

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. 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). 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. 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.

Association between inflammation and changes in residual renal function and peritoneal transport rate during the first year of dialysis.

Peritoneal transport rate, a major determinant of peritoneal dialysis (PD) patient survival, increases in most patients starting on PD, while in other patients peritoneal transport rate may decline. Although several factors may contribute to changes in peritoneal transport rate, inflammation is known to be associated with a high peritoneal transport rate, and residual renal function (RRF), which often declines after start of PD, may also be related to inflammation. Therefore, we hypothesized that changes in peritoneal transport rate during patients' first year on PD and declining RRF may be linked with inflammation. A total of 76 PD patients (40 males, mean age 56.8+/-14.1 years), who underwent two peritoneal equilibration tests at a mean of 0.4 months and 1 year after beginning PD, were included in the study. Based on the change in dialysate to plasma creatinine concentration ratio at 4-h dwell (D/P Cr) during first year on PD, the patients were divided into decreased or unchanged (group DUC; n=22) and increased (group I; n=54) groups. Initially, group I had a lower proportion of high transporters and more often high serum C-reactive protein (sCRP, > or =10 mg/l) and lower RRF compared with the DUC group. In group I, serum albumin and RRF decreased significantly and dialysate protein loss and glucose absorption increased significantly during the first year on PD. When patients were divided into two groups based on median change in RRF (1.9 ml/min), patients with a decrease in RRF >1.9 ml/min during first year on PD had a higher proportion of high sCRP, higher D/P Cr, and higher changes in D/P Cr compared to patients with a decrease in RRF < or =1.9 ml/min. Patients with elevated sCRP at one year included a higher proportion of patients who had high sCRP at the start of PD, higher increase in D/P Cr, lower serum albumin, lower RRF, and more decrease in RRF during first year on PD compared with patients having normal sCRP. RRF was inversely correlated with changes in D/P Cr during the first year on PD (r=-0.28, P=0.02). Multiple regression analysis revealed that the only factors affecting changes in D/P Cr were high sCRP and a low RRF. Our preliminary short-term study suggests that changes in peritoneal transport rate during patients' first year on PD may be linked with inflammation and declining residual renal function. Inflammation and residual renal function were identified as the only independent factors determining peritoneal transport rate during the first year on PD. It is possible that inflammation may cause both an increase in peritoneal transport rate and a decline in residual renal function, or that the decline in residual renal function and the increase in peritoneal transport rate may induce or aggravate inflammation. Further studies are needed to confirm these findings.

The Influence of Demographic Factors and Modality on Loss of Residual Renal Function in Incident Peritoneal Dialysis Patients

To determine whether gender, race, diabetes, peritoneal dialysis (PD) modality, and comorbid conditions influence loss of residual renal function (RRF). Retrospective study of incident PD patients, using database of prospectively collected demographic, laboratory, and clearance data. Peritoneal Dialysis Registry of the University of Pittsburgh Medical Center. The study included 184 continuous ambulatory PD and automated PD patients who had at least two 24-hour urine collections for glomerular filtration rate (GRF) between April 1991 and March 2000. 836 urine collections were analyzed. Loss of RRF was defined as the slope of the decline in GFR as measured by the average of creatinine and urea clearances in 24-hour urine collections. Stepwise forward regression was used to identify demographic and laboratory factors associated with loss of GFR. Spearman correlations were used to assess the significance of associations. The median rate of decline of renal function was -0.17 mL/minute/month. Gender, race, diabetes, automated PD, peritoneal equilibration test, protein equivalent of nonprotein nitrogen appearance normalized to body surface area, and serum albumin did not predict loss of RRF. Cardiac disease was the only variable affecting decline of RRF (p = 0.045). Modality of PD and patient demographic factors do not contribute to the rate at which RRF is lost in incident PD patients. Additional study of the factors contributing to the decline and maintenance of RRF is needed.

Renal Clearances in Continuous Ambulatory Peritoneal Dialysis: Differences between Diabetic and Non-Diabetic Subjects

We analyzed the effect of diabetes on the decline of residual renal function during the course of CAPD in a cross-sectional study including 105 diabetic subjects (41 women) who had 207 clearance studies and 125 non-diabetic subjects (50 women, 265 clearance studies). CAPD duration was 11.5+/-10.5 months in the diabetic group (DG) and 16.8+/-18.6 months in the non-diabetic group (NDG, P < 0.001). The DG had lower urine volume than the NDG (0.52+/-0.46 vs 0.61+/-0.50 L/24-h, P < 0.05), while urine-to-plasma concentration ratio was higher in the DG for creatinine (13.5+/-9.4 vs 11.5+/-11.0, P <0.05) and did not differ for urea. Weekly renal Kt/V urea (DG 0.51+/-0.57, NDG 0.53+/-0.49) and Ccr (DG 31.0+/-28.7 NDG 29.3+/-26.5 L/1.73 m2) did not differ. The slopes of the regressions of CAPD duration on renal clearances did not differ. These regressions allowed estimates of the time, from the onset of CAPD, at which renal clearances become negligible. These estimates differed for both urea clearance (DG 35.3, NDG 50.5 months) and creatinine clearance (DG 43.2, NDG 57.6 months). The slope of the regression of renal urea clearance on renal creatinine clearance was steeper in the DG, suggesting a higher renal creatinine clearance in the DG than in the NDG when renal urea clearance is the same in the two groups. Subtle differences in the rate of decline of renal function can be detected between diabetic and non-diabetic subjects on CAPD by detailed statistical analysis. These findings are supportive of the studies which have identified diabetes mellitus as a predictor of loss of residual renal function during the course of CAPD. In addition, the relationship between the renal urea and creatinine clearances differs between diabetic and nondiabetic subjects on CAPD. Therefore, the dose of CAPD required for adequate total clearances may differ between diabetic and non-diabetic subjects.

Effect of cause and time of dropout on the residual GFR: A comparative analysis of the decline of GFR on dialysis

The decline of residual renal function (RRF) on dialysis has been reported to be slower in peritoneal dialysis (PD) then hemodialysis (HD). However, some clinicians have questioned whether this reported difference might not be caused by selection bias. In particular, if continuous ambulatory PD (CAPD) delivers only marginally adequate therapy as some clinicians speculate, then perhaps those patients on CAPD with low glomerular filtration rate (GFR) are purposefully switched to HD. If true, transferring CAPD patients with low GFR to HD could create a selection bias that very well may account for the differences in GFR between PD and HD. This is particularly problematic if one then censors patients at the time of transfer from PD to HD from analysis (that is, patients are no longer followed in the study once they have switched treatment modalities). When this occurs, the data are said to be informatively censored, a term used by statisticians to describe any kind of systematic bias associated with censored or incomplete data. In particular, informative censoring occurs when patients who die or transfer to another modality very early have an associated lower starting GFR or higher rate of decline of GFR than patients who either complete the study or who die or transfer much later. If patient dropout is indeed related to the rate of decline in GFR and if this relationship differs between PD and HD but is ignored in the analysis, then the results of such analysis may be biased. This article analyzes the decline in GFR among 141 incident dialysis patients (39 HD and 102 PD) undergoing either HD or PD at the University of Missouri-Columbia. The decline in GFR was modeled as a nonlinear function of time, taking into account the possibility that missing values of GFR may be associated with patient dropout (death, transfer to another modality, or transplantation). To safeguard against this possibility, we utilized a conditional nonlinear mixed-effects model. The model was used to fit and compare each patient's GFR data to time adjusting for the patient's treatment modality (HD vs. PD), cause of dropout (death, transfer, transplant, lost to follow-up/study ended), and time to dropout. The model allowed a comparison of the starting GFR and the rate of decline in GFR between PD and HD adjusting for these three factors. The results of our analysis suggest that such informative censoring is independent of treatment modality and that even after correcting for dropout caused by death or transfer to another modality, patients starting on PD have a lower rate of decline in GFR (that is, better preservation of GFR) than patients starting on HD.

Preservation of Residual Renal Function in Dialysis Patients: Effects of Dialysis-Technique–Related Factors

Residual renal function (RRF) is of paramount importance to dialysis adequacy, morbidity, and mortality, particularly for long-term continuous ambulatory peritoneal dialysis (CAPD) patients. Residual renal function seems to be better preserved in patients on CAPD than in hemodialysis (HD) patients. We analyzed RRF in 45 patients with end-stage renal disease (ESRD), commencing either CAPD or HD, to prospectively define the time course of the decline in RRF, and to evaluate dialysis-technique-related factors such as cardiovascular stability and bioincompatibility. Single-center prospective investigation in parallel design with matched pairs. Fifteen patients starting CAPD and 15 matched pairs of patients commencing HD were matched according to cause of renal failure and RRF. Hemodialysis patients were assigned to two dialyzer membranes differing markedly in their potential to activate complement and cells (bioincompatibility). Fifteen patients were treated exclusively with the cuprophane membrane (bioincompatible) and the other 15 patients received HD with the high-flux polysulfone membrane (biocompatible). Residual renal function was determined at initiation of dialytic therapy and after 6, 12, and 24 months. Dry weight (by chest x ray and diameter of the vena cava) was closely recorded throughout the study, and the number of hypotensive episodes counted. Residual renal function declined in both CAPD and HD patients, although this decline was faster in HD patients (2.8 mL/minute after 6 months and 3.7 mL/min after 12 months) than in CAPD patients (0.6 mL/min and 1.4 mL/min after 6 and 12 months respectively). It declined faster in patients with bioincompatible than with biocompatible HD membranes (3.6 mL/min vs 1.9 mL/min after 6 months). Eleven percent of the HD sessions were complicated by clinically relevant blood pressure reductions, but there were no differences between the two dialyzer membrane groups. None of the CAPD patients had documented hypotensive episodes. None of the study patients suffered severe illness or received nephrotoxic antibiotics or radiocontrast media. The better preservation of RRF in stable CAPD patients corresponded with greater cardiovascular stability compared to HD patients, independently of the membrane used. Furthermore, there was a significantly higher preservation of RRF in HD patients on polysulfone versus cuprophane membranes, indicating an additional effect of biocompatibility, such as less generation of nephrotoxic substances by the membrane. Thus, starting ESRD patients on HD prior to elective CAPD should be avoided for better preservation of RRF.

Rate of Decline in Residual Renal Function is Equal in CAPD and Automated Peritoneal Dialysis Patients

Rate of Decline in Residual Renal Function is Equal in CAPD and Automated Peritoneal Dialysis Patients

Preservation of glomerular filtration rate on dialysis when adjusted for patient dropout

Residual renal function (RRF) plays an important role in dialysis patients. Studies in patients on maintenance dialysis suggest that RRF is better preserved in patients receiving peritoneal dialysis (PD) vis-à-vis those receiving hemodialysis (HD). We speculated that regardless of the patient's type of therapy, the estimate obtained for the rate of decline in glomerular filtration rate (GFR) may be biased because of informative censoring associated with patient dropout. Informative censoring occurs when patients who die or transfer to another modality very early have associated with them a lower starting GFR or a higher rate of decline of GFR than patients who either complete the study or who die or transfer much later. If patient dropout is indeed related to the rate of decline in GFR and if this relationship is ignored in the analysis, then the estimate obtained of the rate of decline in GFR may be biased. In an attempt to determine if there is a relationship between patient dropout and the decline in GFR, we reanalyzed the CANUSA data by modeling GFR as a nonlinear function of time with the rate of decline being exponential. This article highlights the significance of "informative censoring" when studying the decline of RRF on dialysis. The results show that for the CANUSA cohort, the mean initial GFR was significantly lower, and the rate of decline was significantly higher for patients who died or transferred to HD than for patients who were randomly censored or received a transplant. It is important to emphasize that the impact of informative censoring on previous analyses of the decline of RRF between PD versus HD is presently unclear. If bias caused by informative censoring is the same regardless of what therapy a patient is on, then conclusions from previous studies comparing the decline in GFR between PD and HD would still be valid. However, if the magnitude of the bias differs according to therapy, then additional adjustments would be needed to fairly compare the decline in GFR between PD and HD. Because this analysis is restricted to patients on PD, it would be scientifically incorrect to interpret previous studies solely on the basis of the results from this analysis. In any longitudinal study designed to estimate trends in an outcome measured over time, it is important that the analysis of the data takes into account any effect patient dropout may have on the estimated trend. This analysis demonstrates that among PD patients, both the starting GFR and the rate of decline in GFR are associated with patient dropout. Consequently, future studies aimed at estimating the rate of decline in GFR among PD patients should also account for any dependencies between dropout and GFR. Similarly, data analyzing for apparent differences in the rate of decline of GFR between PD and HD should also adjust for possible informative censoring.

Continuous Adaptation of the Dialysis Prescription Maintains Adequate Kprt/V in CAPD Patients

To analyze the effect of individual adaptation of the dialysis prescription in continuous ambulatory peritoneal dialysis (CAPD), as compensation for the decline of residual renal function (RRF), on peritoneal (Kpt/V) and total (Kprt/V) urea clearance as well as on peritoneal (Kpcr) and total weekly creatinine clearances (CCr). Retrospective analysis of a 2-year period. We analyzed 18 patients [15 male, 3 female; mean age 58.2 (24 - 80) years]. Correlations between increased dialysis prescription and Kpt/V, Kprt/V, and Kpcr. Kprt/V and CCr measurements were based on a 24-hour dialysate and urine collection. Measurements were performed over a time period of 3 to 6 months. The results show a linear correlation between Kpt/V and Kpcr and the prescribed volume by kilogram body weight. Kprt/V was increased slightly by increasing the dialysis prescription. Dialysate-to-plasma (D/P) ratios of urea and creatinine remained unchanged. The mean prescribed dialysate volume increased from 7.4+/-1.1 L to 10.6+/-2.5 L. Mean Kprt/V could be maintained on a stable level for a 36-month period. By adapting the dialysis prescription on an individual basis to the continuous decline of RRF, and taking the patient's body weight into account in the prescription decision, the increases in Kpt/V offset the decline in RRF. We recommend early individualization of prescription for patients on CAPD.

Rate of Decline of Residual Renal Function in Patients on Continuous Peritoneal Dialysis and Factors Affecting It

We analyzed residual renal function (RRF) in a large number of new peritoneal dialysis (PD) patients to prospectively define the time course of decline of RRF and to evaluate the risk factors assumed to be associated with faster decline. Single-center, prospective cohort study. Home PD unit of a tertiary care University Hospital. The study included 242 patients starting continuous PD between January 1994 and December 1997, with a minimum follow-up of 6 months and at least three measurements of RRF. All patients had data on demographic and laboratory variables, episodes of peritonitis and the use of aminoglycoside (AG) antibiotics, temporary hemodialysis, and number of radiocontrast studies. Adequacy of PD was measured from 24-hour urine and dialysate collection and peritoneal equilibration test using standard methodology. Further data on RRF was collected every 3 to 4 months until the patient became anuric (urine volume < 100 mL/day or creatinine clearance < 1.0 mL/min) or until the end of study in December 1998. The slope of the decline of residual glomerular filtration rate (GFR) (an average of renal urea and creatinine clearance) was the main outcome measure. Risk factors associated with faster decline were evaluated by a comparative analysis between patients in the highest and the lowest quartiles of the slopes of GFR, and a multivariate analysis using a stepwise option within linear regression and general linear models. There was a gradual deterioration of residual GFR with time on PD, with 40% of patients developing anuria at a mean of 20 months after the initiation of PD. On multivariate analysis, use of a larger volume of dialysate (p = 0.0001), higher rate of peritonitis (p = 0.0005), higher use of AG (p = 0.0006), presence of diabetes mellitus (p = 0.005), larger body mass index (BMI) (p = 0.01), and no use of antihypertensive medications (p = 0.04) independently predicted the steep slope of residual GFR. Male gender, higher grades of left ventricular dysfunction, and higher 24-hour proteinuria were associated with faster decline on univariate analysis only. Faster decline of residual GFR corresponds with male gender, large BMI, presence of diabetes mellitus, higher grades of congestive heart failure, and higher 24-hour proteinuria. Higher rate of peritonitis and use of AG for the treatment of peritonitis is also associated independently with faster decline of residual GFR. Whether the type of PD (CAPD vs CCPD/NIPD) is associated with faster decline of residual GFR remains speculative.

Measured-to-predicted creatinine generation ratio increases with time and decline in residual renal function in continuous ambulatory peritoneal dialysis.

The expression of measured-to-predicted creatinine generation ratio (M/P) has been proposed as an index of compliance in continuous ambulatory peritoneal dialysis (CAPD) patients. Although M/P may not be sensitive enough for cross-sectional study, serial monitoring has been suggested to identify noncompliance. We attempted to evaluate serial changes of M/P from a nonselected group of CAPD patients. Sixty-three patients, all followed up for 2 years, were reviewed retrospectively. Their M/P ratios at years 0 and 2 were computed and compared. Baseline M/P had a normal distribution with a mean of 0.96 +/- 0.26. There was significant correlation between baseline M/P and residual glomerular filtration rate (GFR; r = -0.81; P < 0.0001). There were weak correlations between M/P and duration of dialysis (r = 0.52; P < 0.0001), body weight (r = -0.52; P < 0.0001), Kt/V (r = 0.31; P < 0.02), weekly creatinine clearance normalized to body surface area (r = 0.53; P < 0.0001), and serum albumin level (r = -0. 28; P < 0.05). After 2 years, M/P increased in 56 of 63 patients (88. 9%). Average M/P increased from 0.96 +/- 0.26 to 1.31 +/- 0.27 (P < 0.0001). Multivariant analysis showed M/P at year 0, which was largely determined by residual GFR, was the only independent factor affecting increase in M/P from year 0 to year 2. The general trend of increasing M/P was still present when only anuric patients were analyzed, although that was not statistically significant (1.21 +/- 0.14 to 1.32 +/- 0.24; P = 0.12). The finding of increasing M/P with time in CAPD patients, particularly those with significant residual renal function, suggests M/P may not be a reliable indicator of noncompliance, even for serial follow-up of the same patient. Better methods for assessment of compliance in CAPD patients are required.