Survival predictors in anuric patients on peritoneal dialysis: A prospective, multicenter, propensity score-matched cohort study

Prevalent anuric peritoneal dialysis (PD) patients usually have higher mortality than PD patients with residual urine volume. We aimed to evaluate the predictors of survival in anuric PD patients. Anuric PD patients (n = 505, <100 mL of daily urine) enrolled in Korean nationwide prospective cohort were analyzed. Survived and non-survived anuric PD patients were compared by propensity score matching analysis with a ratio of two to one. The propensity method was used to adjust for patient age, dialysis duration, and presence of diabetes. Among the total anuric PD patients, non-survived patients showed a significantly older age, higher incidence of diabetes, coronary artery disease, and arrhythmia, and lower serum creatinine and albumin. After propensity score matching, multivariate Cox regression analysis for patient survival showed a decreasing risk as serum albumin increased (HR = 0.347, p = 0.0094). Analysis using the receiver-operating-characteristic (ROC) curve showed that survival could be predicted with a sensitivity of 59.4% and a specificity of 63.2% using a cutoff value of 3.6 g/dL of serum albumin in unmatched total PD patients. The beneficial impact of high albumin level on death was significantly greater for patients with older age (≥50 years), no diabetes, low ultrafiltration (UF) volume (<1000 mL/day), and low levels of serum creatinine (<10 mg/dL), total cholesterol (<177.5 mg/dL), ferritin (<100 ng/mL), and high-sensitivity C-reactive protein (hs-CRP) (<0.1 mg/dL). Survival in anuric PD patients was associated with age, comorbidities, and nutritional factors such as creatinine and albumin. After adjustment by propensity score matching, serum albumin level was an independent predictor for survival in anuric PD patients.

Comparative Survival Analysis of Urea Kinetic Based Indices

Background

Although urea kinetic modeling indices for measuring dialysis dose are recommended by world expert groups, it is not quite clear whether some of these are superior in predicting the outcome over others. This prospective, single-center study was carried out with the aim to compare predictive value of different indices and methods of measuring dialysis dose.

Methods

The analysis included 93 anuric patients having been on hemodialysis for at least 2 years who were followed-up for 75-months. The dialysis dose was measured by Kt/V (formal UKM, 3 and 2 urea samples), Kt/V (Daugirdas), Kt/V (Lowrie), eKt/V (Daugirdas), URR and TAC urea.

Results

Correlations between dialysis indices and survival time were significant for all indices (p<0.01) except for TAC. All indices, except for TAC urea, were significant predictors of mortality (multivariate Cox regression analysis; p<0.01) and differences of significant levels among these colinear parameters were small.

Conclusion

All examined indices except for TAC urea were highly predictive of patient mortality. Daugirdas and Lowrie simplified Kt/V indices are as predictive of all-cause mortality as more complex formal UKM methods in long-term patients on a 3×4h/week schedule.

Faster Transport Status and Mortality in Anuric Patients Undergoing Continuous Ambulatory Peritoneal Dialysis

BACKGROUND

There are limited data regarding the relationship between transport status and mortality in anuric continuous ambulatory peritoneal dialysis (CAPD) patients.

METHODS

According to the dialysate to plasma creatinine ratio (D/P Cr), 292 anuric CAPD patients were stratified to faster (D/P Cr ≥0.65) and slower transport groups (D/P Cr <0.65). The Cox proportional hazards models were used to evaluate the association of transport status with mortality.

RESULTS

During a median follow-up of 22.1 months, 24% patients died, 61.4% of them due to cardiovascular disease (CVD). Anuric patients with faster transport were associated with an increased risk of all-cause mortality (HR (95% CI) = 2.16 (1.09-4.26)), but not cardiovascular mortality, after adjustment for confounders. Faster transporters with pre-existing CVD had a greater risk for death compared to those without any history of CVD.

CONCLUSION

Faster transporters were independently associated with high all-cause mortality in anuric CAPD patients. This association was strengthened in patients with pre-existing CVD.

Aminophylline improves urine flow rates but not survival in childhood oliguric/anuric acute kidney injury

INTRODUCTION

Acute kidney injury (AKI) morbidity and mortality rates remain high. Variable AKI outcomes have been reported in association with aminophylline treatment. This study evaluated AKI outcome in a group of Nigerian children treated with aminophylline.

METHODS

This is a retrospective study of AKI in children treated with (N=9) and without (N=8) aminophylline. Studied outcome indices comprised urine flow rate (UFR), duration of oliguria/anuria, progression through AKI stages, number of patients requiring dialysis and mortality.

RESULTS

Mean ages for the control and aminophylline arms were 4.6±2.7 and 4.9±2.1 years (P=0.7), respectively. All patients progressed to stage-3 AKI. Baseline median UFRs in the aminophylline and control arms were similar (0.13 Vs 0.04 ml/kg/hour respectively, P=0.5). The median UFR was significantly higher on day-5 (0.8 Vs 0.1; P=0.03), day-6 (1.0 Vs 0.2; P=0.02), and day-7 (1.2 Vs 0.2; P=0.03) in the aminophylline than the control arm, respectively. Short duration of oliguria/anuria (≤ 6 days) was more frequently observed in aminophylline- treated patients compared to controls (77.8% Vs 25.0%; odds ratio 0.09; 95% CI: 0.01-0.89; P=0.04). Only the aminophylline group maintained steady serum creatinine levels. Four out of five patients in the control group were dialyzed compared to only one out of eight patients in the aminophylline group (odds ratio 0.16; 95% CI: 0.04-0.71; P=0.03). Mortality rates were similar in aminophylline- treated and control patients (33% Vs 25%; hazard ratio 0.8; 95% CI: 0.1-5.5; P=0.8).

CONCLUSION

Aminophylline therapy was beneficial for patients with AKI in terms of improved UFR and reduced need for dialysis, but failed to impact positively on survival.

Residual urine output and postoperative mortality in maintenance hemodialysis patients

BACKGROUND

The relationship between residual urine output and postoperative survival in maintenance hemodialysis patients is unknown.

OBJECTIVE

To explore the relationship between amount of urine before surgery and postoperative mortality and differences between postoperative nonanuria and anuria in maintenance hemodialysis patients.

METHODS

A total of 109 maintenance hemodialysis patients underwent major operations. Anuria was defined as urine output <30 mL in the 8 hours before the first session of postoperative dialysis. Propensity scores for postoperative anuria were developed.

RESULTS

Postoperative residual urine output was 159.2 mL/8 h (SD, 115.1) in 33 patients; 76 patients were anuric. Preoperative residual urine output and adequate perioperative blood transfusion were positively related to postoperative urine output. Propensity-adjusted 30-day mortality was associated with postoperative anuria (odds ratio [OR], 4.56; 95% confidence interval [CI], 1.16-17.96; P = .03), prior stroke (OR, 4.46; 95% CI, 1.43-13.89; P = .01) and higher disease severity (OR, 1.10; 95% CI, 1.00-1.21; P = .049) at the first postoperative dialysis. OR of 30-day mortality was 5.38 for nonanuria to anuria vs nonanuria to nonanuria (P = .03) and 5.13 for preoperative anuria vs nonanuria to nonanuria (P = .01). By Kaplan-Meier analysis, 30-day mortality differed significantly among patients for nonanuria to nonanuria, anuria, and nonanuria to anuria (log rank, P = .045).

CONCLUSION

Patients with preoperative nonanuria and postoperative anuria had higher mortality than did patients with no anuria before and after surgery and patients with anuria before surgery. Postoperative residual urine output is an important surrogate marker for disease severity.

What is the link between poor ultrafiltration and increased mortality in anuric patients on automated peritoneal dialysis? Analysis of data from EAPOS

BACKGROUND

Primary analysis of the European Automated Peritoneal Dialysis Outcomes Study (EAPOS) found that patients with daily ultrafiltration (UF) below a predefined target of 750 mL at baseline experienced increased mortality and continuing low UF over 2 years.

SETTING

Multicenter, prospective observational study of prevalent, functionally anuric patients on automated peritoneal dialysis (APD) treated to predefined standards.

METHODS

Secondary data analysis to determine clinical covariates that might support a link between poor UF and outcome, including pattern of comorbidity, prescription, nutrition as determined by Subjective Global Assessment (SGA), membrane function, and blood pressure (BP). Ultrafiltration was treated as a categorical (comparing patients above and below target at baseline) and continuous dependent variable in univariate and multivariate regression. The relationship between BP and survival was also explored.

RESULTS

Of 177 patients recruited from 28 centers across Europe, 43 were below the UF target at baseline. Compared to those above target, there were no differences in the spread of comorbidity, type of APD prescription, SGA, BP, hemoglobin, HCO3, or parathyroid hormone, at baseline or at any later time. At baseline, plasma calcium and, at 12 months, plasma phosphate were lower in the low UF group. There was a weak positive correlation between baseline systolic or diastolic BP and UF, which remained on multivariate analysis but accounted for just 9% of the variability in BP. There was no clear relationship between baseline BP and survival, although, if anything, low BP was associated with earlier death. Poor UF was associated with lower mean dialysate glucose concentration during the first 4 months and with consistently worse membrane function.

CONCLUSIONS

The increased mortality associated with poor UF is likely multifactorial and not easily explained by clear differences in comorbidity, nutritional state, or other indices of treatment at baseline. The lower plasma phosphate suggests a subsequent fall in appetite. Poor BP control is unlikely to be the explanation, and a link between lower BP, reduced UF, and earlier death is suggested. Failure to achieve adequate UF due to worse membrane function remains an important and potentially reversible or preventable cause.

Predictors of survival in anuric peritoneal dialysis patients

BACKGROUND

Residual glomerular filtration rate (GFR) is a much more important determinant of survival in peritoneal dialysis patients, than peritoneal solute clearances. However, anuric peritoneal dialysis patients are solely dependent on peritoneal solute clearances. The aim of the study was to analyze the effects of peritoneal small solute clearances and ultrafiltration on survival in anuric patients, and to establish the minimum levels of small solute clearances and net ultrafiltration. These objectives were investigated in a prospective cohort study in incident peritoneal dialysis patients who had become anuric during follow-up.

METHODS

The Netherlands Cooperative Study on the Adequacy of Dialysis (NECOSAD) is a prospective multicenter cohort study in which new adult dialysis patients are included and followed during 6 months intervals. Included were 542 peritoneal dialysis patients. Of these, 166 developed anuria, 130 of which could be included in the study.

RESULTS

Two-year patient survival after the outset of anuria was 67%, technique survival 73%, and the combined 2-year patient and technique survival was 50%. Risk factors associated with mortality were age, comorbidity, the duration of peritoneal dialysis before anuria, and a low serum albumin. Peritoneal solute clearances were analyzed time-dependently. These parameters were not associated with survival when analyzed as continuous variables and also not when the analyses were done in quintiles, although the time-dependent approach was almost significant for Kt/V(urea). On the other hand, when the results were analyzed dichotomously using predefined cutoff points, Kt/V(urea) <1.5 per week and creatinine clearance <40 L/week/1.73 m2 were associated with an increase in the relative risk of death. Also peritoneal ultrafiltration was significantly associated with survival.

CONCLUSION

The survival of anuric peritoneal dialysis patients is in line with expectations based on the duration of dialysis. The risk factors for death are the same as in the dialysis population as a whole. Besides an association with ultrafiltration, our study enabled us to define the lower limits of adequate peritoneal dialysis, that is Kt/V(urea) <1.5 per week and creatinine clearance <40 L/week/1.73 m2.

Minimal and optimal peritoneal Kt/V targets: results of an anuric peritoneal dialysis patient's survival analysis

BACKGROUND

Residual renal clearance has been shown to be much more predictive of survival than peritoneal clearance. There has been little data to support a target level of peritoneal clearance. A retrospective study was therefore conducted to see how the peritoneal Kt/V had affected the survival of anuric patients in our center.

METHODS

Over a period of 10 years, there were 150 peritoneal dialysis patients with documented anuria. Their survival was analyzed according to their baseline peritoneal Kt/V at the time of documentation of anuria and at the time of their latest altered peritoneal dialysis (PD) prescription (subsequent Kt/V).

RESULTS

There were 90 females and 42 diabetics. The mean age and duration of dialysis were 57.7 +/- 14.7 and 44.1 +/- 31.3 months, respectively. The 2-year and 5-year survival rates were 88.7% and 66.7%, respectively. We found that patients with baseline peritoneal Kt/V below 1.67 had poorer survival after the documentation of anuria than those above [relative risk (RR) 1.985, P= 0.01], although the baseline Kt/V was not an independent risk factors in the whole group of patients. However, such effect was mainly observed in female patients. The survival was identical between those with Kt/V above or below 1.80 (P= 0.98). Among female patients, the group with baseline Kt/V 1.67 to 1.86 had the best survival, followed by those greater than 1.86 and lowest in those below 1.67 (P= 0.0016). For patients with baseline Kt/V below 1.80, those with subsequent Kt/V above 1.76 had better survival than those below (P= 0.033).

CONCLUSION

Our data suggested that a negative effect of peritoneal Kt/V on survival is apparent at a level below 1.67 and there exists a limit of its effect at around 1.80. We suggested a minimal Kt/V target of 1.70 and an optimal target at 1.80 in anuric patients based on survival data. Prospective randomized study is required to confirm this finding.

Survival of functionally anuric patients on automated peritoneal dialysis: the European APD Outcome Study

The European APD Outcome Study (EAPOS) is a 2-yr, prospective, multicenter study of the feasibility and clinical outcomes of automated peritoneal dialysis (APD) in anuric patients. A total of 177 patients were enrolled with a median age of 54 yr (range, 21 to 91 yr). Previous median total time on dialysis was 38 mo (range, 1.6 to 259 mo), and 36% of patients had previously been on hemodialysis for >90 d. Diabetes and cardiovascular disease were present in 17% and 46% of patients, respectively. The APD prescription was adjusted at physician discretion to aim for creatinine clearance (Ccrea) >/=60 L/wk per 1.73 m(2) and ultrafiltration (UF) >/=750 ml/24 h during the first 6 mo. Baseline solute transport status (D/P) was determined by peritoneal equilibration test. At 1 yr, 78% and 74% achieved Ccrea and UF targets, respectively; median drained dialysate volume was 16.2 L/24 h with 50% of patients using icodextrin. Baseline D/P was not related to UF achieved at 1 yr. At 2 yr, patient survival was 78% and technique survival was 62%. Baseline predictors of poor survival were age (>65 yr; P = 0.006), nutritional status (Subjective Global Assessment grade C; P = 0.009), diabetic status (P = 0.008), and UF (<750 ml/24 h; P = 0.047). Time-averaged analyses showed that age, Subjective Global Assessment grade C and diabetic status predicted patient survival with UF the next most significant variable (risk ratio, 0.5/L per d; P = 0.097). Baseline Ccrea, time-averaged Ccrea, and baseline D/P had no effect on patient or technique survival. This study shows that anuric patients can successfully use APD. Baseline UF, not Ccrea or membrane permeability, is associated with patient survival.

Are peritoneal dialysis patients with and without residual renal function equivalent for survival study? Insight from a retrospective review of the cause of death

BACKGROUND

It remains unknown whether results of survival studies in anuric patients can be extrapolated to those who still have significant urine output. It is possible that after a prolonged period on dialysis, anuric patients are qualitatively different from patients with residual renal function.

METHODS

We performed a retrospective review to study the cause of death of 296 peritoneal dialysis patients of our centre over a 7 year period, and compared the mortality and distribution of cause of death between patients with and without residual renal function.

RESULTS

One hundred and forty-two cases (48.0%) died of vascular diseases, 82 cases (27.7%) died of infections and 72 cases (24.3%) died of other causes. Anuric patients had a higher overall mortality rate than non-anuric patients (14.9 vs 9.9%, P=0.0005), and the difference was almost completely attributed to the difference in mortality from vascular diseases (8.0 vs 4.1%, P<0.0001). Vascular disease was a more common cause of death in anuric patients than those with residual renal function (55.3 vs 40.8%, P=0.011). The difference was largely explained by the higher prevalence of sudden cardiac death in anuric patients (39 in 149 vs 19 in 147 cases). Patients without pre-existing cardiovascular disease more commonly died of vascular disease after they became anuric (47.4 vs 34.0%, P=0.017). The difference could not be explained by the longer duration of dialysis in anuric patients because there was no significant change in the distribution of cause of death with time on dialysis (chi-square test, P=0.341).

CONCLUSIONS

Our observation suggests that peritoneal dialysis patients with and without residual renal function are qualitatively different. Studies on peritoneal dialysis adequacy and survival in anuric patients should only be extrapolated to the general dialysis population with caution.

Peritoneal dialysis in anuric patients: concerns and cautions

Most recent studies have found an equivalent survival for patients on peritoneal dialysis (PD) and hemodialysis (HD); evidence even suggests that PD might be the preferred modality during the first 3-4 years of renal replacement therapy. This is probably related to the continuous and minimally invasive character of PD as compared to HD, resulting in better preservation of residual renal function (RRF) and less cardiovascular strain. On the other hand, blood pressure control, fluid balance, and adequacy targets may be difficult to obtain in long-term PD patients. The question arises whether PD is a feasible option in anuric patients. It is clear that the answer depends on the body size and the peritoneal membrane transport characteristics of the patient, so that PD will be feasible in some anuric patients, whereas in others it will not be. Evaluation of the peritoneal transport characteristics and adaptation of the PD prescription is warranted. A constant evaluation of the fluid balance, nutritional, and cardiovascular status is needed. This article reviews the physiologic insights and clinical evidence necessary for a good PD prescription in anuric patients.

Impact of dialysis adequacy on the mortality and morbidity of anuric Chinese patients receiving continuous ambulatory peritoneal dialysis

Dialysis adequacy has a major impact on the outcome of continuous ambulatory peritoneal dialysis (CAPD) patients. However, most studies on peritoneal dialysis adequacy have focused on patients with significant residual renal function. The present study examined the effect of dialysis adequacy on anuric CAPD patients. A single-center prospective observational study on 140 anuric CAPD patients was performed. These patients were followed for 22.0 +/- 11.9 mo. Dialysis adequacy and nutritional indices, including Kt/V, creatinine clearance (CCr), protein equivalent nitrogen appearance, percentage of lean body mass, and serum albumin level were monitored. Clinical outcomes included actuarial patient survival, technique survival, and duration of hospitalization. In the study population, 64 were male, 36 (25.7%) were diabetic, and 59 (42.1%) were treated with 6 L exchanges per day. The body weight was 59.2 +/- 10.2 kg. Average Kt/V was 1.72 +/- 0.31, and CCr was 43.7 +/- 11.5 L/wk per 1.73m(2). Two-yr patient survival was 68.8%, and technique survival was 61.4%. Multivariate analysis showed that DM, duration of dialysis before enrollment, serum albumin, and index of dialysis adequacy (Kt/V or CCr) were independent factors of both patient survival and technique survival. It was estimated that for two patients who differed only in weekly Kt/V, a 0.1 higher value was associated with a 6% decrease in the RR of death (P: < 0.05; 95% confidence interval, 0.92 to 0.99). Serum albumin and CCr were the only independent factors that predicted hospitalization. It was found that even when there is no residual renal function, higher dialysis dosage is associated with better actuarial patient survival, better technique survival, and shorter hospitalization. Dialysis adequacy has a significant impact on the clinical outcome of CAPD patients, and the beneficial effect is preserved in anuric patients as well as in an ethnic group that has a low overall mortality.

The effect of small solute clearances on survival of anuric peritoneal dialysis patients

OBJECTIVE

Primarily, to determine whether peritoneal small solute clearance is related to patient and technique survival among anuric peritoneal dialysis [continuous ambulatory (CAPD) and automated peritoneal dialysis (APD)] patients. A secondary goal was to describe the ability to attain Dialysis Outcomes Quality Initiative (DOQI) targets among anuric patients on peritoneal dialysis.

DESIGN

Retrospective cohort study via chart reviews.

SETTING

Peritoneal Dialysis Unit of Toronto Hospital (Western Division).

PATIENTS

The study included 122 CAPD and APD patients between January 1992 and September 1997, with 24-hour urine volume less than 100 mL, or renal creatinine clearance (CCr) less than 1 mL/minute. Adequacy data were available for 115 patients.

OUTCOME MEASURES

Mortality and technique failure (TF). Regression analysis was used to estimate the mortality and TF rate ratios (RR) for peritoneal Kt/V urea (pKt/V) and pCCr, adjusting for age, gender, diabetes, months of follow-up prior to anuria, albumin, transport status, coronary artery disease, cardiovascular disease, and peripheral vascular disease.

RESULTS

Fifty seven per cent (51/89) of patients on CAPD and 81% (21/26) on APD had a weekly pKt/V > or = 2 and > or = 2.2, respectively (DOQI targets); whereas only 35% on CAPD (31/89) and 35% (9/26) on APD had a weekly pCCr > or = 60 U1.73 m2 and 66 L/1.73 m2, respectively. Median follow-up times among patients were 16.5 and 19.5 months pre- and postanuria, respectively. Patients with pKt/V > or = 1.85 experienced a strong decrease in patient mortality (RR = 0.54, p= 0.10); the effect was less pronounced for pCCr > or = 50 L/1.73 m2 (RR = 0.63, p = 0.25). No relationship was observed between pKt/V or pCCr and TF.

CONCLUSION

Mortality was noticeably less frequent among patients with a pKt/V > or = 1.85 compared with those with a Kt/W < 1.85 (p = 0.10). Given the magnitude of the association, the failure to observe statistical significance relates to the size of the patient cohort. Our results imply that it is, in fact, possible to achieve DOQI targets among anuric patients on peritoneal dialysis.

A further family with congenital renal proximal tubular dysgenesis

A new syndrome of oligohydramnios, Potter's syndrome, and anuric renal failure leading to stillbirth or neonatal death from respiratory failure has recently been described. Histologically, there is renal tubular dysgenesis, especially of the proximal tubules, and apparent glomerular crowding. To date, five families have been reported, in four of which there have been affected sibs and in two parental consanguinity. The disorder is, therefore, thought to be inherited in an autosomal recessive manner.