Comparison between DOQI and Canadian Guidelines for Peritoneal Dialysis

The recently published Canadian Society of Nephrology (CSN) Guidelines for Peritoneal Dialysis Adequacy differ in a number of ways from the United States National Kidney Foundation Dialysis Outcomes Quality Initiative (DOQI) guidelines on the same topic. The three main differences are ( 1 ) the CSN targets are the same for continuous ambulatory peritoneal dialysis (CAPD) and automated peritoneal dialysis (APD), whereas the DOQI targets are higher for APD; ( 2 ) the CSN guidelines have a lower creatinine clearance (CCr) target of 50 L/wk for low and low-average transporters compared to 60 L/wk for high and high-average transporters, but no such distinction is made by DOQI; and ( 3 ) the CSN has set lower limit targets as well as preferred targets for Kt/V and CCr.

Other differences are that the CSN recommendations do not give Kt/V the same primacy over CCr that DOQI does. Also, the CSN recommendations give greater emphasis to the risks associated with high transport status.

This review looks at the reasons for these differences and demonstrates that some are due to information that has become available since the publication of the DOQI guidelines. However, it is emphasized that, when recommendations are predominantly opinion- rather than evidence-based, geographic and economic factors may also account for differences.

Randomized prospective study of the effect of increased dialytic dose on nutritional and clinical outcome in continuous ambulatory peritoneal dialysis patients

Cohort studies have shown that greater urea (Kt/V) and creatinine clearances (CCr) were associated with better survival in patients on continuous ambulatory peritoneal dialysis (CAPD). The possibility of improved patient outcome with increased dialytic dose remains unknown. We prospectively studied over 1 year the effects of an extra 2-L bag on the outcome of 82 patients undergoing three daily 2-L exchanges for at least 12 months. At 1 year, 36 patients were undergoing 6-L exchanges, whereas 30 patients underwent 8-L exchanges. The increased dialytic dose resulted in increased total weekly Kt/V (TKt/V; 1.82 to 2.02), whereas total weekly CCr (TCCr) was maintained (63.2 to 61.9 L/1.73 m(2)). Control patients had reduced solute clearances (TKt/V, 1.87 to 1.67; TCCr, 64.8 to 54.6 L/1.73 m(2)). The fourth bag exchange resulted in a significant increase in net ultrafiltration (0.83 to 1.51 L/d), whereas the control group also had greater ultrafiltration (0.68 to 1.01 L/d) after 1 year. Although the normalized protein equivalent of nitrogen appearance (nPNA) was stable in the controls, the patients using 8-L exchanges achieved a greater nPNA (1.10 to 1.24 g/kg/d). There was no associated change in serum albumin levels (3.79 to 3.48 g/dL). The hospitalization rate increased in the controls (0.9 to 1.8 admissions/12 mon), whereas it was unchanged in the patients using 8-L exchanges. In conclusion, a 33% increase in dialytic prescription led to increased peritoneal and total clearances. Despite achieving increased nPNA (13%), the serum albumin level was unchanged. However, the increased hospitalization rate observed in the controls was avoided in the group using 8-L exchanges.

Morbidity and mortality in redefining adequacy of peritoneal dialysis: a step beyond the National Kidney Foundation Dialysis Outcomes Quality Initiative

The National Kidney Foundation Dialysis Outcomes Quality Initiative (NKF-DOQI) Peritoneal Dialysis (PD) Adequacy Work Group intentionally limited the scope of its work to address adequacy in terms of small-solute removal. This decision was based on the need for rigorous evidence and that mortality is the most objective parameter in the literature. This review attempts to more broadly redefine the concept of the adequacy of PD, particularly as it relates to the most common general medical problems that PD patients experience; namely, cardiovascular disease and malnutrition. Whereas we are sensitive to the developmental process of the NKF-DOQI, we are critical that the definition of adequacy may be too narrow, leading clinicians to overlook other important morbidities. We have reiterated the evidence that suggests a weekly solute clearance (Kt/Vurea) of 1.7 or greater is associated with better patient survival. The arguments to target a greater Kt/Vurea of 2.0 are challenged, yet the concept is ultimately supported. Because cardiovascular disease is the cause of death in half of all patients with end-stage renal disease, dialysis adequacy must be defined, in part, by the potential of that therapy to diminish cardiovascular maladies. Blood pressure, volume, left ventricular hypertrophy, and dyslipidemias are discussed in this context. Lastly, assumptions that increasing total solute clearance leads to improved nutrition in PD patients are challenged. We have attempted to expand on what the NKF-DOQI did not include, and we urge the dialysis community to seek the answers to the many controversies that remain. We need to redefine the adequacy of PD in a holistic manner and find outcome parameters that are not as final as death.

Peritoneal dialysis

Peritoneal dialysis has now become an established form of renal replacement therapy; nearly half the patients on dialysis in the UK are treated in this way. Survival of patients is now equal to that with haemodialysis. However, long-term peritoneal dialysis (>8 years) is limited to a small percentage of patients because of dropout to haemodialysis for inherent complications of peritoneal dialysis--peritonitis, peritoneal access, inadequate dialysis, and patient-related factors. However, improvements in the understanding of the pathophysiological processes involving the peritoneal membrane have paved the way for advances in the delivery of adequate dialysis, more biocompatible dialysis fluids, and automated peritoneal dialysis. Other technical advances have led to a reduction in peritonitis. Peritoneal dialysis is an important dialysis modality and should be used as an integral part of RRT programmes.

Report from the 1995 Core Indicators for Peritoneal Dialysis Study Group

The 1995 Peritoneal Dialysis Core Indicators Study was conducted by the Health Care Financing Administration to ascertain standard practices and outcomes in chronic peritoneal dialysis patients. Data from 1,202 patients who did not receive hemodialysis but who were on chronic ambulatory peritoneal dialysis (CAPD) for at least part of the 6-month period between November 1, 1994, and April 30, 1995, are reported. The mean serum albumin level for this cohort was 3.5 g/dL by the bromcresol green method and 3.2 g/dL by the bromcresol purple method. Data sufficient to calculate a weekly Kt/V(urea) or weekly creatinine clearance were available for only 34% of patient submissions. In these patients, the median weekly Kt/V(urea) was 1.7 using a fixed value for V of 0.58 x body weight and was 2.0 using the Watson equation to calculate V; the median weekly creatinine clearance was 60.7 L/wk/1.73 m2. The mean hematocrit for this cohort was 32% and the average weekly recombinant human erythropoietin (rHmEPO) dose was 115 u/kg. Hematocrit values < or = 30% were found in 50% of black patients and 31% of white patients. The average blood pressure among peritoneal dialysis patients was 139/80 mm Hg, with 29% of patients having a systolic blood pressure exceeding 150 mm Hg and 18% a diastolic blood pressure greater than 90 mm Hg. In summary, serum albumin levels were significantly lower in peritoneal dialysis patients than in hemodialysis patients. Approximately one third of peritoneal dialysis patients did not have an adequacy measure obtained during the 6-month observation period. A significant minority of patients had either inadequately treated anemia of chronic renal disease or hypertension. There is an opportunity to substantially improve the medical care provided to chronic peritoneal dialysis patients.