Daily peritoneal ultrafiltration predicts patient and technique survival in anuric peritoneal dialysis patients

Transcription

1 2322 X. Lin et al. gy data. Journal of the American Statistical Association 1993; 88: Bodnar E, Blackstone EH. An actual problem: another issue of apples and oranges. J Thorac Cardiovasc Surg 2006; 131: Therneau TM, Grambsch PM. Modeling survival data: extending the Cox model. New York: Springer Verlag, Williamson PR, Kolamunnage-Dona R, Smith CT. The influence of competing-risks setting on the choice of hypothesis test for treatment effect. Biostatistics 2007; 8: Bajorunaite R, Klein JP. Comparison of failure probabilities in the presence of competing risks. J Stat Comput Simul 2008; 78: Couchoud C, Duman M, Frimat L et al. RDPLF and Rein, 2 complementary registries: a comparison of the collected data. Nephrol Ther 2007; 3: Rothman K, Greenland S. Modern Epidemiology. Philadelphia: Lippincott-aven, Siva B, Hawley CM, McDonald SP et al. Pseudomonas peritonitis in Australia: predictors, treatment, and outcomes in 191 cases. Clin J Am Soc Nephrol 2009; 4: Miles R, Hawley CM, McDonald SP et al. Predictors and outcomes of fungal peritonitis in peritoneal dialysis patients. Kidney Int 2009; 76: Andersen PK, Abildstrom SZ, Rosthoj S. Competing risks as a multistate model. Stat Methods Med Res 2002; 11: Cook RJ, Lawless JF. Marginal analysis of recurrent events and a terminating event. Stat Med 1997; 16: Dauxois JY, Sencey S. Non-parametric tests for recurrent events under competing risks. Scandinavian Journal of Statistics 2009; 36: Sozio SM, Armstrong PA, Coresh J et al. Cerebrovascular disease incidence, characteristics, and outcomes in patients initiating dialysis: the Choices for Healthy Outcomes in Caring for ESRD (CHOICE) Study. Am J Kidney Dis 2009; 54: Scrucca L, Santucci A, Aversa F. Competing risk analysis using R: an easy guide for clinicians. Bone Marrow Transplant 2007; 40: Received for publication: ; Accepted in revised form: Nephrol Dial Transplant (2010) 25: doi: /ndt/gfq001 Advance Access publication 29 January 2010 Daily peritoneal ultrafiltration predicts patient and technique survival in anuric peritoneal dialysis patients Xinghui Lin 1, Aiwu Lin 1, Zhaohui Ni 1, Qiang Yao 2, Weiming Zhang 1, Yucheng Yan 1, Wei Fang 1, Aiping Gu 1, Jonas Axelsson 3 and Jiaqi Qian 1 1 Renal Division, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Center for Peritoneal Dialysis Research, Shanghai, China, 2 Baxter Renal, China and 3 Department of Clinical Science, Karolinska Institutet, Stockholm, Sweden Correspondence and offprint requests to: Jiaqi Qian; jiaqiqian@126.com Abstract Background. Maintenance dialysis therapy is the only way to remove excess fluid in patients with anuric end-stage renal disease. The optimal ultrafiltration (UF) volume in patients on peritoneal dialysis (PD) remains controversial. Methods. We retrospectively analysed a cohort of 86 prevalent anuric PD patients followed up for a median of 25.3 months (range, 6 to 54 months). Clinical and PD parameters were recorded yearly. Kaplan Meier analysis and Cox proportional hazards models were used to identify risk factors of mortality and technique failure in patients with a UF 1 L/24 h or <1 L/24 h. Results. When compared to those with a UF <1 L/24 h, patients with a UF 1 L/24 h had significantly higher haemoglobin levels (101.9 ± 20.5 vs 89.3 ± 20.2 g/l, P < 0.05) and tended to be younger (55.0 ± 12.5 vs 60.6 ± 16.1 years, P = 0.10). Also, while Kt/V and CCr were stable over time, UF decreased significantly over the study period (baseline, ± ml/24 h vs after 3 years, ± ml/24 h; P < 0.001). Using Kaplan Meier analysis, patients with baseline UF <1 L/24 h had significantly worse outcome (survival, 27.2 ± 3.9 vs 42.4 ± 1.9 months; P < 0.001). In multivariate Cox regression analysis, age, time-dependent UF volume and serum albumin were independent predictors of mortality, while UF independently predicted technique failure. Conclusions. The present study demonstrates a strong predictive value of daily peritoneal UF for both technique and patient survival in prevalent anuric PD patients. Identifying markers of satisfactory fluid status, as well as optimizing therapy to meet UF goals, remains an important clinical target. Keywords: anuria; patient survival; peritoneal dialysis; technique survival Introduction Over the past four decades, peritoneal dialysis (PD) has been an important form of renal replacement therapy for patients with end-stage renal disease (ESRD). Previous The Author Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved. For Permissions, please journals.permissions@oxfordjournals.org

2 Daily peritoneal UF predicts patient and technique survival 2323 Table 1. Baseline data of 86 anuric PD patients divided by calculated peritoneal UF All patients UF 1 L/24 h UF <1 L/24 h P-value No. of patients Gender (M:F) 37:49 29:37 8:12 Age (years) 56.3 ± ± ± 16.1 NS Previous months on PD (months) 41.4 ± ± ± 24.8 NS Haemoglobin (g/l) 99.0 ± ± ± 20.2 <0.05 Systolic BP (mmhg) ± ± ± 25.7 NS Diastolic BP (mmhg) 86.1 ± ± ± 14.5 NS Instilled dialysate volume (L) 7.60 ± ± ± 0.98 NS Urine output (ml/24 h) 23.6 ± ± ± 44.7 NS BUN (mmol/l) 21.2 ± ± ± 6.7 NS Scr (µmol/l) ± ± ± NS Kt/V urea 1.75 ± ± ± 0.31 NS CCr (L/week/1.73 m 2 ) 46.2 ± ± ± 10.6 NS Serum albumin (g/l) 36.5 ± ± ± 4.5 NS UF rate (ml/24 h) ± ± ± <0.001 Diabetic status, n (%) 20 (23.3) 14 (21.2) 6 (30.0) NS D/P Cr 0.62 ± ± ± 0.11 NS Renal diagnosis Chronic glomerulonephritis Diabetic nephropathy Hypertensive nephrosclerosis Polycystic kidney disease Lupus nephritis Other/unknown Data are expressed as mean ± SD, P-values result from comparisons of baseline values of the two groups divided by baseline UF. BUN, blood urea nitrogen; Scr, serum creatinine; CCr, total weekly creatinine clearance; UF, ultrafiltration; NS, not significant. studies have reported similar patient survival rates for PD and haemodialysis when appropriate adjustments are made for differences in case mix [1]. However, a number of studies have shown that fluid overload is prevalent in PD patients, especially in patients who have lost their residual renal function (RRF) [2 4]. Inadequate fluid removal in this population contributes to hypertension and is associated with an increased risk of cardiovascular disease [5], hypoalbuminaemia [6] and systemic inflammation [7]. Indeed, reanalysis of the large CANUSA study has shown that the decrease in RRF, rather than peritoneal creatinine clearance, best predicts both mortality and morbidity in PD patients [8]. According to this analysis, every increase of 250 ml in urine output leads to a 36% decrease in mortality risk [8], again suggesting the important role of fluid status in predicting clinical outcome. Ultrafiltration (UF) over the peritoneal membrane during dialysis is the standard therapy for removing excess fluid in anuric patients on PD, but the optimal UF volume in this population remains controversial. The European Best Practice Guideline Working Group on Peritoneal Dialysis set an arbitrary target that the minimum net UF in anuric PD patients should be 1 L/day [9]. However, the International Society for Peritoneal Dialysis believes that no numerical target for UF can be formulated using the present data [10]. In the present study, we performed a retrospective cohort study of prevalent anuric PD patients in our centre. We aimed to study the impact of attaining peritoneal UF targets on clinical outcome in anuric Chinese patients. Materials and methods Patient selection We retrospectively evaluated 86 prevalent anuric PD patients from the PD unit of Renji Hospital who became anuric between 1 January 2003 and 31 October 2007 and followed them up for a median of 25.3 months (range, 6 to 54 months) until 30 April Anuria was defined as a 24-h urine output of 100 ml. All patients were regularly monitored in our centre and had started their PD treatment at least 6 months before enrolment. Exclusion criteria were survival <6 months, transfer to haemodialysis or kidney transplantation within 6 months, having an active systemic inflammatory disease and/or having unstable organ disease, such as hepatic failure or class 3 4 according to the New York Heart Association Classification for congestive heart failure. Baseline data including age, sex, aetiology of renal disease, PD regimen, duration on dialysis before enrolment, presence of diabetes mellitus and blood pressure (BP) were recorded. All of the included patients were prescribed a glucose-based PD solution with at least three 2-L exchanges per day. Most were receiving other drugs common in ESRD, including antihypertensive medication, erythropoietin and phosphorus binders. Data collection Dialysis adequacy was monitored at least yearly by 24-h dialysate collections [11], UF rate was calculated as the difference between the volume of total dialysate infused and the volume drained over 24 h and daily UF was corrected for overfill. Adequacy of dialysis was estimated by measurement of weekly Kt/V urea and weekly creatinine clearance (CCr) using PD-ADEQUEST (Baxter Healthcare Corporation, Chicago, IL, USA). We also assessed peritoneal equilibration test [12] yearly. Biochemical tests including blood urea nitrogen (BUN), serum creatinine, glucose, calcium and phosphorus levels and serum albumin were also examined using standard equipment (ADVIA1650, Bayer Corporation) for the same period. The POET and PD-ADEQUEST software (Baxter Healthcare Corporation, Chicago, IL, USA) were used to assist with data management.

3 2324 X. Lin et al. Table 2. Longitudinal changes in small solute clearance, albumin level, UF rate, instilled dialysate volume and content of glucose in dialysate during the study period, and grouped according to follow-up time and baseline UF 1 L/24 h and <1 L/24 h Follow-up Baseline One year Two years Three years No. of patients Kt/V urea 1.75 ± ± ± ± 0.35 UF 1 L/24 h 1.77 ± ± ± ± 0.24 UF <1 L/24 h 1.70 ± ± ± ± 0.59 CCr (L/week/1.73 m 2 ) 46.2 ± ± ± ± 10.4 UF 1 L/24 h 46.7 ± ± ± ± 7.2 UF <1 L/24 h 44.5 ± ± ± ± 13.6 Serum albumin (g/l) 36.5 ± ± ± ± 3.6 UF 1 L/24 h 36.9 ± ± ± ± 3.5 UF <1 L/24 h 35.3 ± ± ± ± 4.4 UF rate (ml/24 h) ± ± ± 310.2* ± 439.8* UF 1 L/24 h ± ± ± ± UF <1 L/24 h ± ± ± ± Instilled dialysate volume (L/day) 7.60 ± ± ± ± 1.15 UF 1 L/24 h 7.70 ± ± ± ± 1.24 UF <1 L/24 h 7.30 ± ± ± ± 1.00 Content of glucose in dialysate (g/day) ± ± ± ± 44.7 UF 1 L/24 h ± ± ± ± 44.1 UF <1 L/24 h ± ± ± ± 52.5 D/P Cr 0.62 ± ± ± ± 0.12 UF 1 L/24 h 0.61 ± ± ± ± 0.11 UF <1 L/24 h 0.66 ± ± ± ± 0.14 CCr, total weekly creatinine clearance; UF, ultrafiltration. * P < 0.001, compared with baseline data, ANOVA. Statistical analysis Statistical analysis was performed using SPSS 15.0 for Windows (SPSS Inc., Chicago, IL, USA). Results are expressed as mean ± SD. Comparison of means and percentages was performed using paired and unpaired ANOVA or a chi-square test. Correlations were analysed using Pearson s correlation coefficient. The Cox proportional hazards model was used for statistical analysis of survival. Baseline parameters with a P-value <0.05 in univariate Cox regression were then incorporated into a final multivariate Cox regression analysis. Backward stepwise elimination using the Wald test was applied to remove insignificant variables. UF was treated as a time-dependent variable in the final Cox model. Similarly, we performed the same analysis to assess associations between clinical parameters and technique failure, defined as transfer to haemodialysis or death. We also performed Kaplan Meier survival analysis; dividing the patients according to baseline UF 1 L/24 h or <1 L/24 h, which coincided with the UF target recommended by the European Best Practice Guideline Working Group on Peritoneal Dialysis [9], a ROC curve was made to determine the sensitivity and specificity of UF in predicting mortality. Results Baseline characteristics Eighty-six patients were enrolled, with a median follow-up of 25.3 ± 12.4 months. Baseline clinical characteristics are Table 3. RR of death in univariate Cox regression for selected variables at baseline in 86 anuric PD patients RR 95% CI P-value Age (1 year) <0.001 Gender (female) NS Previous months on PD (1 month) NS Systolic BP (10 mmhg) <0.01 Diastolic BP (10 mmhg) NS BUN (1 mmol/l) <0.01 Scr (100 µmol/l) <0.01 Kt/V urea (0.1 unit/week) NS CCr (1 L/week/1.73 m 2 ) NS Haemoglobin (1 g/l) NS Serum albumin (1 g/l) <0.001 UF rate (100 ml/24 h) <0.001 Diabetic status (present) <0.01 D/P Cr (0.1) NS BUN, blood urea nitrogen; Scr, serum creatinine; CCr, total weekly creatinine clearance; UF, ultrafiltration; NS, not significant. summarized in Table 1. Briefly, compared to patients with a UF <1 L/24 h, patients with a UF 1 L/24 h had signif-

4 Daily peritoneal UF predicts patient and technique survival 2325 Table 4. Multivariate Cox regression analysis showing independent predictors of mortality in 86 anuric PD patients followed up for a median of 25.3 months (range, 6 to 54 months) Table 5. Multivariate Cox regression analysis showing independent predictors of technique failure in 86 anuric PD patients followed up for a median of 25.3 months (range, 6 to 54 months) RR 95% CI P-value Age (1 year) Serum albumin (1 g/l) UF(t) (100 ml/24 h) The original model included age, systolic BP, serum albumin, diabetic status and time-dependent UF. RR 95% CI P-value Serum albumin (1 g/l) UF(t) (100 ml/24 h) Systolic BP (mmhg) The original model included age, systolic BP, serum albumin, diabetic status and time-dependent UF. icantly higher haemoglobin levels (101.9 ± 20.5 g/l vs 89.3 ± 20.2 g/l, respectively; P < 0.001) and tended to be younger (55.0 ± 12.5 years vs 60.6 ± 16.1 years, respectively; P = 0.10). Longitudinal data During the study period, 40 patients dropped out. Ten patients were switched to haemodialysis, four patients received transplants and 26 died. Cardiovascular disease was the leading cause of death, while infection was the second most common cause of death. Eight patients were transferred to haemodialysis due to severe peritonitis, one due to hernia and one due to inadequate dialysis. Table 2 shows the longitudinal changes in dialysis adequacy parameters as well as serum albumin level, UF rate, instilled dialysate volume, input glucose content and dialysate/plasma creatinine ratio (D/P Cr) at baseline and during the study period. Briefly, despite the fact that instilled dialysate volume and input glucose content tended to increase with time, UF decreased significantly (baseline, ± ml vs after 3 years, ± ml; P < 0.001). While D/P Cr tended to increase after 3 years, none of the other markers changed during follow-up Survival analysis The relative risks (RRs) of death associated with baseline parameters are summarized in Table 3. Briefly, age, systolic BP, BUN, serum creatinine, serum albumin, diabetic status and UF rate were each predictors of death in univariate analysis, whereas neither Kt/V urea nor CCr predicted mortality. In multivariate Cox analysis (Table 4), age, baseline albumin and time-dependent UF rate were each independent predictors of mortality. Likewise, Kaplan Meier analysis showed that patients with a UF above 1 L/24 h survived significantly longer than those with a UF below 1 L/24 h (median survival, 42.4 ± 1.9 vs 27.2 ± 3.9 months; P < 0.001) (Figure 1). The UF ROC curve showed that the area under the curve is (P < 0.001); when UF is equal to 1.0 L/day, the sensitivity of UF in predicting mortality is between (UF = 1025 ml/24 h) and (UF = 975 ml/24 h) and the specificity is between (UF = 975ml/24 h) and (UF = 1025 ml/24 h). Technique survival Table 5 shows independent predictors of technique failure analysed using a Cox model and only time-dependent rate was found to predict technique failure. Figure 2 shows the Kaplan Meier estimates of technique survival, which suggests that patients with a baseline UF 1 L/24 h had statistically significant better technique survival compared with those with a baseline UF <1 L/24 h (median survival, 37.8 ± 2.0 vs 26.3 ± 3.8 months; P = 0.002) Cum Survival Log rank test P <0.001 Cum Survival Log rank test P < Months Fig. 1. Kaplan Meier survival curves for all-cause mortality in 86 anuric PD patients grouped according to baseline UF of 1 L/24 h (dashed) and <1 L/24 h (solid); P < Months Fig. 2. Kaplan Meier survival curves of technique survival in 86 anuric PD patients grouped according to baseline UF of 1 L/24 h (dashed) and <1 L/24 h (solid); P < 0.01.

5 2326 X. Lin et al. Discussion In a retrospective analysis of PD patients that became anuric and were followed up for a median of 25.3 months, we confirm the strong prognostic value of peritoneal UF. In fact, compared to other commonly used markers of dialysis adequacy such as Kt/V urea and CCr, UF was a more potent predictor of both mortality and technique failure in our analysis. This finding was in agreement with previous studies. Ates et al. have found that total fluid removal including UF and urine output was an independent predictor of patient survival [13], whereas Kt/V urea and CCr were not predictors. While the European APD Outcome Study (EA- POS) found that a baseline UF <750 ml/24 h, but not CCr, predicted a poor survival in anuric automated PD patients [14]. Additionally, the Netherlands Cooperative Study on the Adequacy of Dialysis (NECOSAD) also related peritoneal UF to survival in anuric patients on PD [15]. All of these studies were performed on mainly non-asian populations; as it is well-known that Asian patients tend to preserve their peritoneal function longer on PD [16], we demonstrated that UF also strongly influenced clinical outcome in anuric Chinese patients on PD. Unfortunately, a number of studies have shown that a dysfunction of UF is not rare in long-term PD [17,18]. The present study also found that UF volume gradually decreased with time despite that fact that instilled dialysate volume and input glucose content tended to increase. The precise mechanism of this phenomenon remains to be elucidated, but a frequent peritonitis and the bioincompatible PD solutions such as high glucose, hyperosmolality, low ph and glucose degradation products leading to a high peritoneal transport status or peritoneal fibrosis are thought to be responsible for this. Several studies have shown that the dysfunction of UF was a leading cause of PD dropout [19,20]. The impaired UF capacity aggravates the volume expansion and consequent poor survival rate despite having good urea and creatinine clearance [21 23]. It should be pointed out that patients with obvious oedema and incurable hypertension in our unit are informed to restrict their water and sodium intake. However, some patients with subclinical volume expansion due to unconsciously impaired UF are likely to drink too much. Thus far, the optimal UF volume in anuric patients on PD remains controversial [9,10]. Theoretically, a target of UF in anuric PD patients seems to be logical, which will facilitate a timely therapeutic intervention when UF declines to a dangerous level while the patient is only in asymptomatic fluid overload status. In the present study, a Kaplan Meier survival analysis indicated that a baseline UF <1 L/24 h was associated with significantly higher mortality and technical failure than a baseline UF over 1 L/24 h. This finding demonstrates a strong predictive value of peritoneal daily UF for clinical outcome in anuric patients on PD. Interestingly, we did find that few of the surviving patients with strictly restricted water and sodium intake had a baseline UF <1 L/24 h over 2 years of follow-up. Thus, it could be deduced that the better prognosis of patients with UF over 1 L/24 h is likely to be associated with an adequate fluid removal which leads to a better fluid balance. Similar to the findings from other studies [24 26], we found that a decrease of albumin was significantly associated with poor survival. We also noticed that patients with UF <1 L/24 h had significantly lower haemoglobin levels and tended to be hypoalbuminaemic compared with others with better UF. We speculated that the lower haemoglobin and hypoalbuminaemia in patients with less UF was in part related to fluid overload, as previous studies have shown that volume expansion in PD patients would contribute to hypoalbuminaemia [6]. We failed to demonstrate that Kt/V urea is a predictor of clinical outcome in anuric patients, a result that is similar with that of EAPOS [14]. However, this does not mean that Kt/V urea is unimportant; it is noticeable that the median value of Kt/V urea, either in surviving patients or in deceased patients (1.77 ± 0.31 vs 1.70 ± 0.26, P > 0.05), has reached 1.7, a minimum target recommended by K/ DOQI [27]. Our previous study found that when Kt/V urea was <1.7, the PD patients had worse survival than those having higher Kt/V urea values [28]. In any case, a combination of Kt/V urea and other important factors such as UF and fluid balance should be used to determine the adequacy of dialysis. The limitations of the present study include its design with a relatively small number of patients and the fact that it was a retrospective study, not a prospective study. Moreover we do not have any objective marker of fluid status in these patients. In spite of these shortcomings, this study could provide some useful information based on a realworld practice, performed in a single centre in Chinese population, which excluded the centre effect and any ethical differences regarding prognosis. Conclusion In conclusion, we confirm the previously reported strong prognostic impact of peritoneal UF in anuric PD patients and we demonstrate a strong predictive value of daily peritoneal UF for both technique and patient survival in this population. While current guidelines do not adequately address the optimum UF target in anuric patients on PD, identifying markers of satisfactory fluid status, as well as optimizing therapy to meet UF goals, remains an important clinical target. Acknowledgments. This study was supported in part by the Shanghai Commission of Science and Technology (no. 08dz ). Conflict of interest statement. None declared. References 1. Fenton SSA, Schanbel DE, Desmeules M et al. Hemodialysis versus peritoneal dialysis: a comparison of adjusted mortality rates. Am J Kidney Dis 1997; 30: Rottembourg J. Residual renal function and recovery of renal function in patients treated by CAPD. Kidney Int 1993; 43: S106 S Lameire N, Vanholder RC, Van Loo A et al. Cardiovascular diseases in peritoneal dialysis patients: the size of the problem. Kidney Int 1996; 50: S28 S36

6 Daily peritoneal UF predicts patient and technique survival Tzamaloukas AH, Saddler MC, Murata GH et al. Symptomatic fluid retention in patients on continuous peritoneal dialysis. J Am Soc Nephrol 1995; 6: Silberberg JS, Barre P, Prichard S et al. Impact of left ventricular hypertrophy on survival in end-stage renal disease. Kidney Int 1989; 36: Jones CH, Smye SW, Newstead CG et al. Extracellular fluid volume determined by bioelectric impedance and serum albumin in CAPD patients. Nephrol Dial Transplant 1998; 13: Chung SH, Heimburger O, Stenvinkel P et al. Association between inflammation and changes in residual renal function and peritoneal transport rate during the first year of dialysis. Nephrol Dial Transplant 2001; 16: Bargman JM, Thorpe KE, Churchill DN. Relative contribution of residual renal function and peritoneal clearance to adequacy of dialysis: a reanalysis of the CANUSA study. JAmSocNephrol2001; 12: The European Best Practice Guideline Working Group on Peritoneal Dialysis: adequacy of peritoneal dialysis. Nephrol Dial Transplant 2005; 20: ix24 ix Lo WK, Bargman JM, Burkart J et al. Guideline on targets for solute and fluid removal in adult patients on chronic peritoneal dialysis. Perit Dial Int 2006; 26: Szeto CC, Wong TY, Leung CB et al. Importance of dialysis adequacy in mortality and morbidity of Chinese CAPD patients. Kidney Int 2000; 58: Twardowski ZJ, Nolph KD, Khanna R et al. Peritoneal equilibration test. Perit Dial Int 1987; 7: Ates K, Nergizoglu G, Keven K et al. Effect of fluid and sodium removal on mortality in peritoneal dialysis patients. Kidney Int 2001; 60: Brown EA, Davies SJ, Rutherford P et al. Survival of functionally anuric patients on automated peritoneal dialysis: the European APD Outcome Study. J Am Soc Nephrol 2003; 14: Jansen MA, Termorshuizen F, Korevaar JC et al. Predictors of survival in anuric peritoneal dialysis patients. Kidney Int 2005; 68: Pei YP, Greenwood CM, Chery AL et al. Racial differences in survival of patients on dialysis. Kidney Int 2000; 58: Davies SJ, Bryan J, Phillips L et al. Longitudinal changes in peritoneal kinetics: the effects of peritoneal dialysis and peritonitis. Nephrol Dial Transplant 1996; 11: Heimburger O, Waniewski J, Werynski A et al. Peritoneal transport in CAPD patients with permanent loss of ultrafiltration capacity. Kidney Int 1990; 38: Korbet SM, Rodby RA. Peritoneal membrane failure: differential diagnosis, evaluation, and treatment. Semin Dial 1994; 7: Kawaguchi Y, Hasegawa T, Nakayama M et al. Issues affecting the longevity of the continuous peritoneal dialysis therapy. Kidney Int 1997; 52: S105 S Wang T, Heimbürger O, Waniewski J et al. Increased peritoneal permeability is associated with decreased fluid and small-solute removal and higher mortality in CAPD patients. Nephrol Dial Transplant 1998; 13: Bos WJ, Struijk DG, van Olden RW et al. Elevated 24-hour blood pressure in peritoneal dialysis patients with ultrafiltration failure. Adv Perit Dial 1998; 14: Churchill DN, Thorpe KE, Nolph KDA et al. Increased peritoneal membrane transport is associated with decreased patient and technique survival for continuous peritoneal dialysis patients. The Canada-U.S.A. (CANUSA) Peritoneal Dialysis Study Group. JAmSoc Nephrol 1998; 9: Churchill DN, Taylor DW, Keshaviah PR. The Canada-USA (CANU- SA) Peritoneal Dialysis Study Group: adequacy of dialysis and nutrition in continuous ambulatory peritoneal dialysis patients. J Am Soc Nephrol 1996; 7: Szeto CC, Wong TYH, Chow KM et al. Impact of dialysis adequacy on the mortality and morbidity of anuric Chinese patients receiving continuous ambulatory peritoneal dialysis. J Am Soc Nephrol 2001; 12: Paniagua R, Amato D, Vonesh E et al. Effects of increased peritoneal clearances on mortality rates in peritoneal dialysis: ADEMEX, a prospective, randomized, controlled trial. J Am Soc Nephrol 2002; 13: Peritoneal Dialysis Adequacy Work Group. Clinical practice guidelines for peritoneal dialysis adequacy. Am J Kidney Dis 2006; 48: S98 S Yao Q, Lin A, Qian et al. The adequacy of peritoneal dialysis in a single Chinese center. Hong Kong J Nephrol 2001; 3: Received for publication: ; Accepted in revised form: