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

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Abstract

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 m2). Control patients had reduced solute clearances (TKt/V, 1.87 to 1.67; TCCr, 64.8 to 54.6 L/1.73 m2). 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.

Section snippets

Patients

Of the 122 patients undergoing CAPD for at least 12 months in the renal unit of Kwong Wah Hospital (Kowloon, Hong Kong) from April 1994 to May 1995, a total of 82 patients (47 men, 35 women; mean age, 53.7 years; range, 28 to 76 years) agreed to participate in the study. Patients on daytime ambulatory peritoneal dialysis (PD) or nightly intermittent PD therapy, those with amputations, or bedridden patients were excluded from the study. At the beginning of the study, patients had been undergoing

Results

Sixty-six of the 82 patients completed the 12-month study. The dropout rate was similar for the two groups (6 of 42 versus 10 of 40 patients; P = not significant [NS]). Six patients (6-L group, 2 patients; 8-L group, 4 patients) underwent transplantation. Four patients (2 patients in each group) died of cerebrovascular disease (3 patients) or intestinal obstruction secondary to fungal peritonitis (1 patient). Six patients (6-L group, 2 patients; 8-L group, 4 patients) were switched to

Discussion

CAPD is an increasingly used treatment modality for end-stage renal failure worldwide. It is preferred to hemodialysis in our population as a result of our unique socioeconomic background. Three daily 2-L exchanges has been the standard starting therapy for CAPD in most centers of Hong Kong because of a smaller body size in general. Our local data have confirmed that approximately 50% of PD patients have a weekly Kt/V less than the commonly agreed target of 1.7 for adequate dialysis.26 If we

Acknowledgements

Acknowledgment: The authors acknowledge the help of the renal nursing staff of Kwong Wah Hospital and Pamela Youde Polyclinic Renal Dialysis Center.

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    *

    Received October 6, 1999; accepted in revised form January 28, 2000.

    **

    Supported in part by a grant from the Baxter Healthcare Corporation.

    *

    Address reprint requests to Siu-Ka Mak, MD, Renal Unit, Department of Medicine, Kwong Wah Hospital, 25 Waterloo Rd, Kowloon, Hong Kong. E-mail: [email protected]

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