LIMITATIONS OF KINETIC-MODELS AS PREDICTORS OF NUTRITIONAL AND DIALYSIS ADEQUACY IN CONTINUOUS AMBULATORY PERITONEAL-DIALYSIS PATIENTS

Nutrition has been shown to predict clinical outcome in continuous amb ulatory peritoneal dialysis (CAPD) patients. However, despite the posi tive relationship between KT/V (urea) and the normalised protein catab olic rate, the ability of urea kinetic modelling to predict clinical o utcome or nutrition remains inconclusive. We have evaluated the relati onship between nutrition and achieved dialysis in a cross-sectional st udy of 147 stable CAPD patients on dialysis for a mean period of 22 mo nths. Protein-energy malnutrition was present in 22-32% of the study p opulation. 39 and 41% of the population failed to achieve suggested ad equacy targets of 50 litres/week for total creatinine clearance and a weekly KT/V(urea) of 1.7, respectively. Severely malnourished patients had significantly greater normalised clearance and adequacy values th an well-nourished patients. Intrinsic actual peritoneal clearance bore no relation to patient size. The subsequent normalisation of this val ue by a component of patient mass results in a mathematical bias again st well-nourished or obese patients. This may explain the failure of s uch adequacy values to reflect outcome and argues against accepting su ch values as measures of dialysis well-being.